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r X35;1973 C.2 NBS-PUB-C 1959 NBS MONOGRAPH 135

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no. 155

c-Z

U.S.

DEPARTMENT

OF

COMMERCE

National

Bureau

of

Standards

Properties of Glasses

in Some Ternary Systems

Containing BaO and Sio

2
NATIONAL BUREAU OF STANDARDS

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National Bureau c St£

MAY 1 3 1974 Properties of Glasses

in Some Ternary Systems

Containing BaO and Si0 2

Given W. Cleek

Institute for Materials Research

National Bureau of Standards

Washington, D.C. 20234

C. L. Babcock

Optical Sciences Center

University of Arizona

Tuscon, Ariz. 85721

U.S. DEPARTMENT OF COMMERCE, Frederick B. Dent, Secretary

NATIONAL BUREAU OF STANDARDS, Richard W. Roberts, Director

Issued September 1973
Library of Congress Catalog Number: 73-600135

National Bureau of Standards Monograph 135

Nat. Bur. Stand. (U.S.), Monogr. 135, 42 pages (Sept. 1973) CODEN: NBSMA6

For sale by the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402

(Order by SD Catalog No. C13.44:135). Price 70 cents. Stock Number 0303-01157
Properties of Glasses in Some Ternary Systems Containing BaO andSi02 *

G. W. Cleek and C. L. Babcock**

The glass forming regions in six ternary oxide systems containing BaO, SiC>2, and a third oxide have been determined. The properties of the resulting glasses were measured and the results re- ported. The data on refractive indices, dispersions, and specific volumes were evaluated by computer methods in an attempt to identify "substructures" containing the cations present in the glasses. Key words: Barium glasses; barium silicates; glass properties; glass property factors; oxide glasses;

silicate substructures; ternary glasses.

1. Introduction

During the course of several years, while working

on the development of special purpose oxide glasses

for various applications, surveys of the regions of

glass formation in some ternary systems containing

BaO and Si02 have been made. The systems sur- veyed are as follows:

1. BaO-Ti02 -Si02 2. BaO-La2 03 -Si02 3. BaO-Ta2 05 -Si02 4. BaO-ZnO-Si02 5. BaO-Nb2 05 -Si02 6. BaO-Al2 03 -Si02

It was believed that the properties measured on

the glasses are of sufficient interest to glass technologists to be made generally available and are published here.

2. Experimental Procedure

The experimental glasses were normally made in 500 g melts from batch materials of sufficient purity

to satisfy the requirements for the production of

optical glass. The standard procedure was to melt

the batches in platinum crucibles, 6.5 cm in diameter by 7.5 cm deep. After the batch was melted,

the melt was stirred for 2 h with a motor driven

platinum-10-percent-rhodium, double-bladed pro- peller-type stirrer. The furnace used for melting was heated by silicon carbide resistance elements

so that the furnace atmosphere was not contaminated by combustion products. After the melt was

stirred, it was poured into a heated metal mold to form a block about 7.5 cm by 7.5 cm by 2.0 cm thick. When sufficiently rigid, the glass block was trans- ferred to an electric muffle furnace, which was

cooled to room temperature in approximately 18 h.

Part of the work described in this report was sponsored by the Department of the Navy at the National Bureau of Standards, and by Project Themis, U.S. Air Force, at the University of Arizona. "'Address: Optical Sciences Center, University of Arizona, Tucson, Arizona 85721.

1 The figures in brackets indicate the literature references at the end of the paper.

Only those compositions that could be melted below

1500 °C and in which no appreciable devitrification occurred during cooling were considered to produce

glasses. These experimental conditions were used

to define the regions of glass formation in the

ternary systems studied, and no attempt was made

to enlarge these regions by melting at a higher

temperature or by cooling the melts more rapidly

to avoid devitrification. The properties determined for most of the

experimental glasses included the following:

(1) Sag Point [l] 1

(2) Refractive index for the C (A = 0.6563 /xm),

D (k = 0.5893 yum), and F (\ = 0.4861 /xm)

spectral lines. From these the reciprocal

dispersive power, commonly known as the Nu

value, v, was calculated.

nD — 1 v=

nF — nc

(3) Liquidus temperature [2] (4) Infrared transmittances for 2 mm thickness

from 1 to 6 /xm.

For the more promising glasses certain other

properties were measured. These included infrared

transmittances for greater thicknesses, usually 8

mm, so that absorption coefficients could be computed; infrared refractive indices; linear coefficient of thermal expansion; and deformation temperature.

For some glasses density, chemical durability, and

elastic constants were also measured.

In addition, data on refractive indices (n/;), dispersions and specific volume were evaluated,

using previously described methods [3]. One

purpose of this evaluation is to develop quantitative

property-composition relations for use by technologists in formulating glasses for optical uses. A

further purpose is to clarify presently incomplete

knowledge of the ternary phase diagrams of these

glass-forming systems and to identify, if possible,

"substructures" containing the cations present in the glasses.

1
3. Glass-Forming Systems

Investigated

Several ternary silicate systems were investigated

as to the extent of the region of glass formation and

the properties of the glasses obtained.

3.1. The BaO-Ti02 -Si02 System

In an effort to produce glasses having high values

of refractive index at wavelengths of 2.0 to 2.5 ^m,

good infrared transmittances and good chemical

durability melts were made in the ternary system

BaO-Ti02-Si02 [4]. Most high-index glasses presently available are either extra-dense flint glasses,

which have a high PbO content, or rare-earth

borate glasses [5]. The extra-dense flint glasses

have fairly good infrared transmittances, cutting

off, as do most silicate glasses, at about 5 /im.

They have high refractive indices, but their chemical

durability is rather poor and they have low deformation temperatures. The B2O3 content of most rare- earth glasses makes them useless for infrared

applications.

The phase equilibrium diagram for the ternary

system BaO-Ti02-Si02 has not been determined,

but information is available on the binary sides

of the ternary system [6, 7, 8]. Rase and Roy

have determined the liquidus temperatures and

phase relations along the line BaO • Ti02-Si02

in the ternary diagram [9J. This information was

very useful in selecting compositions in the ternary

system that could be melted and cooled as glasses.

The composition of all melts made in the ternary

system are given in table 1 and are plotted in the

ternary diagram in figure 1. As may be seen from

the figure, the longest BaO isopleth along which

glasses were formed is the 25 mol percent line. Although glasses are not formed on this line to the

BaO-Si02 binary, glass formation begins at about

the 20 mol percent of TiC>2 and extends to relatively

high concentrations of Ti02 . This fine of glass

formation seems to follow a valley in the liquidus

surface, as may be seen from table 1. The color of the glasses changed very markedly

as the TiC>2 content was increased. Those containing

up to about 15 mol percent of Ti02 were nearly

colorless, whereas those containing intermediate

amounts from 20 to 35 mol percent of TiC>2, were

orange colored, and the others having about 40

mol percent of Ti02 were dark brown to black. Evidently, as the TiC>2 content is increased, the

absorption increases at the shorter wavelengths in the visible region, and at higher TiC>2 concentrations

very little visible light is transmitted.

Figure 1. Compositions studied in the system BaO-Ti02 -Si02 .
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4
The liquidus temperature [2] for each composition is given in table 1. It will be noticed from the

table that in no case was a glass formed from a composition that had a liquidus temperature greater

that 1400 °C. The lowest liquidus temperatures were found along the 25 mol percent BaO isopleth,

which is also the longest line of glass formation in the system. Furthermore, the shape of the liquidus curve of the 25 mol percent BaO series in the areas

of best glass formation is relatively flat, indicating a high degree of dissociation of the primary phase at the liquidus temperature. Probably, the ease of

glass formation is related to the degree of dissociation of the primary phase in the melt, because

similar observations have been made for this and

other glass forming systems [10]. In the BaOB203-SiO-2 system, the glasses whose compositions lie in the 3BaO • 3B 2 03 2Si0 2 primary

field, which has a flat liquidus curve, were the ones

that were melted and homogenized with the least

difficulty and had the least tendency to devitrify.

The refractive index, no, and v are plotted in figure 2 for the three BaO isopleths along which

glasses were obtained. The values of tii> varied from

1.63139 to 1.87988, and v from 49.9 to 25.3. The

refractive index appears to be a linear function of composition. The plots of v definitely show

curvature. Figures 3 to 9, inclusive, give the transmittances

for 2-mm thicknesses of the ternary glasses over

the spectral range 1 to 5 fim. The figures compare

glasses of constant Ti02 content. In general the

glasses giving the highest transmittance at 4 jam

lie on the 30-mol percent BaO isopleth up to a Ti0 2 concentration of 25 mol percent, then the compositions shift to the 25-mol-percent BaO iospleth.

There are considerable differences in the transmit- tances of the various glasses, but no simple rela- tionship between transmittance and composition

is readily evident.

The values of chemical durability [11] of five representative ternary glasses are given in table 2

50

46

42

38 -

34

30

26

22

1.90

qI.85

x

LU9 1.80

<

a.

cr

.75

1.70

.65

35 BaO

25 BaO

10 15 20 25 MOLE PERCENT Ti02

30 35

Figure 2. Plot of refractive index and v as a function of composition for the glass-forming compositions in the BaO-Ti02

- Si02 system.

5
100

901-

80

70

60

-X X—X—X—%

i—

r

~i i i

i

i I r

5 50

Z 40

30

20

10 -

J I L

2 3 4 WAVE LENGTH , MICROMETERS

J L_\ J

100

2 3 4 WAV E LENGTH , MICROMETERS

FIGURE 3. Spectral transmittance of 2-mm thickness of two

glasses containing 5 mol percent o/Ti02 . •F152, X F144. Figure 5. Spectral transmittance of 2-mm thickness of three glasses containing 15 mol percent of Ti02 .#F149,oF142,

XF49.

100

90

80

70

60

50

4 0

30

20

10

i i

i r

i—I—I—i—i—

r

-X M X X XJ I I 1 L

100

"12 3 4 WAVELENGTH , MICROMETERS

FIGURE 4. Spectral transmittance of 2-mm thickness of two

glasses containing 10 mol percent o/TiO>. ©FSS, x F143.

I

1 1

90 -

80 -

70

60

z

< 50

40

30

20

10

_a—»

h—kx—x—x-x-'

12J I L J I I I I L

3 4 WAVELENGTH , MICROMETERS

Figure 6. Spectral transmittance of 2-mm thickness of two

glasses containing20 mol percent o/Ti02 .* F148, X F40.

6
100 "i—i i I r "i i

I

i—

r

90 -

t— K A » » *"

80

70

60

fr 50

40

30

20 12J I L J I L 3 4 WAVELENGTH , MICROMETERS

FIGURE 7. Spectral transmittance of 2-mm thickness of two

glasses containing 25 mol percent o/Ti02 .*F147, X F95.

100

90 -

80

ui 70 o

z

<H 60 I

(/) z

< 50

tr

\—

z 40

UJo

(T

UJ

°- 30

20

n—

r

i—i—l—I—l—l—l—I i i r

2 3 4 WAVELENGTH , MICROMETERS

FIGURE 9. Spectral transmittance of 2-mm thickness of two

glasses containing 35 mol percent o/Ti02 . •F145, x F139.

100

90

80 -

ui 70 o

z

<H 60

2 50

IZ 40

UJo

ccLU

°- 30

20

10

i—

r

i—i—

r

i |

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J I L I I I I I i I I I I 2 3 4 WAVELENGTH , MICROMETERS

FIGURE 8. Spectral transmittance of 2-mm thickness of two

glasses containing 30 mol percent o/Ti02 . 0F146, x F138.

and are plotted as a function of pH in figure 10. All values are for 6 h of exposure at 80 °C. As may

be seen from the figure, the glass containing 60 mol

percent of SiC>2 is attacked in the alkaline range. As SiC>2 is replaced by TiO-z, the attack in this range

is decreased, and although slight attack or swelling

is noticed at pH 2, the glasses containing 20 mol

percent and more of TiC>2 show no attack in the

alkaline range. The hygroscopicity [12], or the tendency of a powdered-glass sample to absorb water in a humid

atmosphere, was very low for the samples of the

ternary glasses on which determinations were made.

The values obtained were, in all cases, equal or

less than fused silica which was used for purposes

of comparison. These data are given in table 2 and

plotted in figure 11. The resistance of these glasses to chemical

attack and their low hygroscopicity make them

unique as compared to known oxide glasses.

The linear coefficient of thermal expansion [13] has been determined for only three representative

ternary glasses. The values obtained were 9 or 10XlO_6/°C, which is near the values of most

commercial soda-lime-silica glasses. The deformation temperatures are somewhat higher than the

usual values for silicate glasses. The expansion

curves for three glasses are plotted in figure 12.

7
Table 2. Hygroscopicity and chemical durability of BaOTi02-Si02 glasses

Melt

Water

sorbed

Surface alteration," fringes, at pH —

(exposures, 6 h at 80 °C)

1 h 2 h 2.0 4.1 6.0 8.2 10.2 11.88

F35

mglcm1

5.7

6.1 5.2

mglcm 3 10.0

9.1 8.2

ND

ND

1/10 A

2/10 S

1/10 S

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

ND

DA

ND

1/2 A

ND

ND

ND

ND

1/4 A

DA

2 A

2/10 A

ND

ND

ND

i If A

1/2 A

F49

F40

F95 F138

Corning

7740 ... Fused

SiC-2 ...

15.9

6.2

28.3

12.1

a ND, No detectable attack; A, attack of surface; S, swelling

of surface; DA, detectable, but not measurable attack.

The deformation temperatures varied from 767 °C

for glass F35, containing 10 mol percent of Ti02,

to 791 °C for glass F138, having 30 mol percent of

T1O2. The high deformation temperatures of these

glasses make them unique as compared to most

commercial glasses. Other data given in table 1 are the densities of several of the glasses as well as

their sag points.

EXPOSURE , HOURS

Figure 11. Hygroscopicity of three BaO-Ti02 -Si02 glasses compared with Corning 7740 glass andfused Si02.

8
SiOp

TEMPERATURE, °C

FIGURE 12. Thermal expansion curves of three BaO-Ti02 -Si02 glasses as determined by an interferometric method.

3.2. The BaO-La20:,-Si0 2 System

Lanthanum oxide is used in optical glasses to produce relatively high values of refractive index

with little or no increase in the dispersion values in the visible region. A survey of the glass forming

region of the ternary system BaO-La203-Si02 was

made. No data on the liquidus temperatures in the

system were available except those in the binary

BaO-SiC>2 system [8J which forms one side of the

o CONTAINED CRYSTALLINE

MATERIAL

• CLEAR GLASS

I CM >,90

2 CM \80

3Cv< \70

K60

5 00BaO

10 20 30 40 50 MOLE PERCENT 2 3 Figure 13. Compositions studied in the system BaO-La2 03-Si02 .

ternary system. Since then a tentative diagram for the BaO-La20:j system [14] has been published. A

eutectic point at about 1370 °C near the composition

30 mol percent BaO_70 mol percent SiOi served as a starting point.

The region of glass formation is shown in the

triangular diagram in figure 13. Glasses were formed to the 12 mol percent La20.3 isopleth.

While these compositions appear to contain rather

small amounts of La-zOz, it must be remembered

that on a weight percent basis the La203 content amounts to about 35 percent. The compositions

melted and the properties of the resulting glasses are listed in table 3. The refractive index, no, varied from 1.6097 to 1.7027 with v from 56.0 to 50.8. The densities of

the glasses ranged from 3.623 to 4.169 g/cm3

, and

the coefficient of thermal expansion ranged from

8.4 to 11.4 X 10-6/°C.

The coefficients of thermal expansion of the

glasses are plotted as a function of the composition

in figure 14. The plots show an anomolous behavior

i3.o x icr 6

' I

1 "1—

T

n—I—

r

i—i—

r

MOLE PERCENT BaO

FIGURE 14. Plot of linear coefficients of thermal expansion as a function of composition for glasses in the BaO-La2 03 -Si0 2 system.

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Li. Li_ U. Lj- U. Li. Li.

NH/iOiOnO-hcni-OOnCO CMlOtPlOCMcOcOcOCMCM nOlOlOlOlonOnOnOnOnO

Li-Li.Li.Li-Li-Li,Li_u.Li,Li.

10
Figure 15. Spectral transmittance of 2-mm thickness of glasses containing 2 mo!

percent of La2 0:i . • F558, OF548, X F634.

for the 5 and 7 mol percent La20:s lines, and it is possible that the 2 mol percent line would show a

similar behavior if data were obtained at higher

BaO concentrations. The increase in the values of

coefficient of expansion with increasing amounts

of BaO, and decreasing SiO-2 content, is not surprising. But the curve reaches a maximum and then

decreases as the SiC>2 content continues to decrease.

An explanation for this behavior is not readily

apparent.

At the same time, for each La2 0;j isopleth, there

is little change in deformation temperature, so that

it does not appear that the increase in the coefficient

of expansion is due solely to a loosening of the struc- ture as more BaO is incorporated into the glass. As

shown in the table the deformation temperatures of

the glasses vary little within each series, but definitely increase as the LaaOs content of the glasses

increases.

The transmittance curves for 2-mm thicknesses

of glasses in the 2, 5, 7, and 10 mol percent La20u

series are plotted in figures 15, 16, 17, and 18. The

curves are plotted from the limit of transmittance

in the ultraviolet to 0.5 (xm and from 2.0 /xm to the

limit of transmittance in the infrared. While trans- mittance values have not been measured from

0.5 to 1.0 fxm, there is no reason to expect any

change in transmittance in this region because the

glasses are clear and show no evidence of absorption. The ultraviolet limit of transmittance, about

0.260 /im, is somewhat beyond the usual run of

glasses. Window glass, for instance, does not trans- mit beyond about 0.320 fim in 2.0 mm thicknesses,

thicknesses. In the infrared there are variations in

100

90

80

LU

<_> |

70 ^ 60

CO< 50

tr. ^40

ZIII 3 30

tr

l±J °- 20

I 0

i i r

V

.260 .300 .340 .380 .420 .460 .500 2 3 4 5 WAVELENGTH, MICROMETERS FIGURE 16. Spectral transmittance of 2-mm thickness of glasses containing 5 mol percent of La>0-,. •F525, X F551, F527.

the transmittance curves between 3 and 4 ^m, but no simple relation with composition is readily

evident.

3.3. The BaO-Ta2 05-Si02 System

Tantalum oxide, used as a component of glass,

imparts higher refractive index values and higher

dispersions than does La20:;. A survev of the glassforming region of the BaO-Ta205-Si02 ternary

system was made. Again no data were found on the

liquidus temperatures in the svstems except for the

BaO-Si02 binary system [8]. The eutectic point

in the binary system at about 1370 °C served again

as a starting composition.

11
WAVELENGTH, MICROMETERS

FIGURE 17. Spectral transmittance of 2-mm thickness of glasses containing 7 mol

percent o/La2 03 . •F552, X F530, - - F553.

T I I—I—I—1—

r

260 .300 .340 .380 420 460 500 2 3 4 5 WAVELENGTH, MICROMETERS

FIGURE 18. Spectral transmittance of 2-mm thickness of glasses containing 10 mol

percent o/La203.« F554, x F545,OF555.

The region of glass formation is shown in the

triangular diagram in figure 19. The compositions

melted and the properties of the glasses are given in table 4. The glasses form series along the 2, 5, 7, and 10 mol percent Ta2 0s isopleths as may be' seen from the figure. The refractive index, ni>, varied

from 1.6112 to 1.7708 with v from 53.5 to 39.4. The

densities of the glasses ranged from 3.672 to 5.015

g/cm 3

. The coefficients of thermal expansion were

determined for only two glasses, one in the 5 mol

percent and one in the 10-mol-percent Ta20s

series. The values were 8.3 X 10"6 and 9.5 X 10-6/°C

respectively. The deformation points for the two

glasses were 800 and 853 °C, which are rather high

compared to those of most silicate glasses.

The transmittances from the limit of trans- mittance in the ultraviolet to 0.500 /zm, and from

2 (Mm to the limit of transmittance in the infrared

for 2-mm thicknesses of glasses from the 2, 5, 7, and 10 mol percent series are given in figures 20,

21, 22, 23, and 24.

12
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13
BaO Ta2°5 MOLE PERCENT

FIGURE 19. Compositions studied in the system BaO-Ta2 05-Si02 .

3.4. The BaO-ZnO-Si02 System

ZnO may be used as a component of glass. It imparts intermediate values of refractive index and some glasses containing ZnO have relatively low

values of thermal expansion. A survey of the glassforming region of the BaO-ZnO-Si02 system was

made. Data on the binary BaO-SiO-2 [8] and the

ZnO-Si0 2 [15] systems are available.

The region of glass formation found in the system

is shown in the triangular diagram in figure 25, and

the compositions melted are listed in table 5. As s may be seen from the figure clear glasses were ob- tained over a considerable area of the diagram.

The liquidus temperatures of the various compositions are also given in table 5. The glasses, over a

relatively large composition area, have liquidus

temperatures below 1300 °C. A smaller area has

liquidus temperatures below 1200 °C and a still smaller area has temperatures below 1100 °C. The j minimum liquidus temperature found was 1089 °C

for a glass on the 26-mol-percent BaO isopleth.

The refractive index values for glasses in the system are also given in the table. The values range

from 1.5878 to 1.6785 for n D with v from 48.4 to 56.8. The transmittance curves for2-mm thicknesses of glasses from the 36, 30, 26, 20, 14, and 10 mol percent

BaO series are given in figures 26, 27, 28, 29, 30,

and 31, respectively. For each series there is con- siderable spread in the transmittance values for the region between 2.75 to 4.0 (xm as the Si02

content is varied. If one examines the transmittance

values at 3.5 ixm as the BaO content is decreased, it appears that the trend is for a decrease in transmit- tance from the 36 to the 30 mol percent series. Then

the trend is for a gradual increase from the 30 to the 10 mol percent series. It would appear from the general shapes of the curves that some of the varia- tions are due to the (OH) - content of the glasses.

t i i I i i i I i i r

.260 .300 .340 .380 .420 .460 .500 2 3 4 5 WAVELENGTH, MICROMETERS

Figure 20. Spectral transmittance of 2-mm thickness of glasses containing 2 mol

percent o/Ta2 0.-,.«F522, X F588.0 F576.

14
260 .300 .340 .380 .420 .460 .500 2 3 4 WAVELENGTH, MICROMETERS

FIGURE 21. Spectral transmittance of 2-mm thickness of glasses containing 5 mol

percent o/Ta205. • F532. X F534. A F542.

.260 .300 .340 .360 .420 .460 .500 2 3 4 WAVELENGTH, MICROMETERS

Figure 22. Spectral transmittance of 2-mm thickness of glasses containing 5 mnl

percent o/Ta,05 . • F579, X F580, OF540.

15
80

£ 70

a 30

"i—i—

i—i—i—

r

o'

.260 .300 .340 .380 .420 .460 .500 2 3 WAVELENGTH, MICROMETERS

Figure 23. Spectral transmittance of 2-mm thickness of glasses containing 7 mol

percent o/Ta2 05 . «F584, X F615, OF591.

1 i I r

80

i

60 z

<

a: 50

it-5 40

20

o 1 260 J I I I I I I I I

I i .300 340 .380 .420 .460 .500 2 3 WAVELENGTH. MICROMETERS

FIGURE 24. Spectral transmittance of 2-mm thickness of glasses containing 10 mol

percent o/Ta2 05 . #F616, OF617.

16
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20
Figure 25. Compositions studied in the system BaO-ZnO-Si02 .

BaO ZnO

MOLE PERCENT

21
100

Figure 27. Spectral transmittance of 2-mm thickness of glasses containing 30 mol percent of BaO. - F690, «F692, A F694, X F711.

WAVELENGTH, MICROMETERS

Figure 28. Spectral transmittance of 2-mm thickness of glasses containing 26 mol percent of BaO. X F705, »F707, A F709, - F716.
100

Figure 29. Spectral transmittan.ee of 2-mm thickness of glasses containing 20 mol percent of BaO.»F733, A F763, x F735.

1.5 3 4 WAVELENGTH, MICROMETERS

FIGURE 30. Spectral transmittance of 2-mm thickness of glasses containing 14 mol percent of BaO.«F816, A F802, x F805.

3 4 WAVELENGTH, MICROMETERS

23
s

tnz

<

WAVELENGTH, MICROMETERS

FIGURE 31. Spectral transmittance of 2-mm thickness of glasses containing 10 mol percent o/BaO.«F813, A F801, x F804.

3.5. The BaO-Nb>05 -Si02 System

Nb^'O.-,, when used as a component of glass,

imparts relatively high values of refractive index

along with high dispersion, or low v. The glassforming region of the BaO-Nb20.-,-Si02 system was

determined. Information on the binary sides,

BaO-SiO- [8], BaO-Nb205 [16], and Nb2 0 5

- SiOa [17], is available, but the ternary system has

not been worked out. The region of glass formation in the system is shown in the triangular diagram in figure 32, and

the compositions melted and their measured properties are listed in table 6. Except for the 2 and 6 mol

percent glasses, most of the melts had liquidus temperatures below 1300 °C. A minimum value of 1152

°C was found for one glass in the 14-mol-percent

Nb205 series. Glasses were formed to remarkably

low Si02 contents, as may be seen from the table and from figure 32. Glass F1466 contained 38- mol-percent SiGV

The refractive index, ranged from 1.615 to 1.902 with v from 51.7 to 27.6. The transmittance curves for 2 mm thicknesses

of the glasses from the 2, 6, 10, 14, 18, and 22 mol

percent Nb^Os series are shown in figures 33 to 38. respectively. As the Nb20s content of the glasses

increase the minimum in transmittance in the 2.75

to 4 jLtm region increases. This evidently is related

to the (OH) - content of the glasses and to the manner

in which (OH) -is bound, but no general explanation of this behavior is readily seen.

24
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25
WAVELENGTH, MICROMETERS FIGURE 33. Spectral transmittance of 2-mm thickness of glasses containing 2 mol percent of Nb2 05 . OF1431, •F1432, + F1433, x F1434.

26
Figure 39. Compositions studied in the system BaO-Al2 03-Si02 and approximate

phase boundaries.

27
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28
3.6. The BaO-ALO , Si02 System

Alumina is widely used as a component of glass.

Morey [18] states that "alumina in small quantity

is a frequent constituent of glass. It gives greater

chemical durability, lower coefficient of expansion,

and greater freedom from devitrification." It has

long been known that small amounts of AI2O3 improved the flame working properties of thermometer

glass [19].

Aluminate glasses [20, 21] have been of interest

because of their improved infrared transmittance

as compared to most silicate glasses. An area of

glass formation in the CaO-A^O.s system is the basis

for these glasses. Aluminosilicate glasses [22] containing 20 to 40 percent AI2O3, have high soften- ing temperatures, relatively low thermal expansion

coefficients, and high values of hardness. They have

been used for lamp envelopes, chemical combustion

tubes and "top-of-stove" ware. The ternary diagram for the BaO-Al2 03-Si0 2 system [23] has been published along with isofracts

for the ternary glasses [24]. More recently Forster

et al. [25] have made further studies in this ternary

system and have revised the earlier diagram.

The compositions melted in this work are listed in table 7 along with the properties measured on the

resulting glasses. The 10 mol percent AI2O3 series

fall near the phase boundary between the ternary

compound BaO AI2O3 • 2Si0 2 and the binary

barium silicates. This is illustrated in the ternary

diagram shown in figure 39, where the compositions

melted and the approximate location of the phase

boundaries as determined by Foster et al. [25],

and by Thomas [24] are plotted. The refractive in- dex, ud varied from 1.5940 to 1.6536 with v in the

range from 51.4 to 57.0. The transmittance curves for 2-mm thicknesses

of representative glasses from 6, 8, and 10 mol per- cent AI2O3 series are plotted in figures 40, 41, and

42, respectively. Again, as the Al 2 0:i content of the

glasses increase the minimum in transmittance in the 2.75 to 4.0 /xm region moves to higher values. No general explanation of this behavior is readily

evident other than that it is related to (OH)~ content

of the glasses and the manner in which the (OH)" is bound.

The thermal expansion of glass F1123 is shown in figure 43. The linear coefficient of thermal expansion

over the temperature range from 100 to 600 °C is 8.1 X 10_6/°C which is only slightly lower than

ordinary window or plate glass. The deformation

temperature is 797 °C which is considerably higher

than most ordinary glasses.

100

2 3 4 5 6 WAVELENGTH, MICROMETERS

FIGURE 40. Spectral transmittance of 2-mm thickness of glasses containing 6 mol percent o/Al 2 0:l .«F1164, X F1166, A F1169.

100

3 4 5 WAVELENGTH, MICROMETERS

FIGURE 41. Spectral transmittance of 2-mm thickness of glasses containing 8 mol percent of AhO:t . • F1124. x F1132. A F1133.

29
WAVELENGTH, MICROMETERS

Figure 42. Spectral transmittance of 2-mm thickness of glasses containing 10 mol percent o/Al2 03 . •Fim, - F1129,

F1130, x F1143.

50 100 200 300 400 500 600 700 800

TEMPERATURE, °C

FIGURE 43. Thermal expansion of Glass F 1123 as determined by

an interferometric method.

Linear coefficient of thermal expansion (100-600 °C) is 8.1 X 10"6/°C and deformation temperature is 797 °C.

4. Analytical Representation of Data

Composition-property data in the six ternary

barium silicate glass systems have been quantitatively evaluated following the method of Babcock

[3]. Data on refractive index and specific volume, in a number of silicate glass systems, were segregated

into groups according to the composition ranges and

areas covered by the known primary crystallization

phase fields involved. The separate groups of data, one group for each primary phase field, were then

subjected to least-squares computer analysis. The

program called for determining the role of each

oxide in linear equations of the form

Glass Property = ^Si0 2 + fiCaO + CNa2 0 + . . .

A, B, and C are numerical constants characteristic

of the respective oxides and amounts of oxides are expressed in mole fractions. The fidelity with which

the equations represent the measured data is in- dicated by the computerized standard error /X(AP) 2 V N-l

wherein AP is the difference between measured and

calculated data and N equals the number of measurements. This work [3] demonstrated that data on several

hundred silicate glasses, measured by the National

Bureau of Standards and the Geophysical Laboratory, Carnegie Institute of Washington, could be

accurately represented to the fourth decimal place

by such linear equations. This accuracy was good

enough to permit calculation of phase boundaries

and compositions of invariant points in binary and

ternary silicate glass systems. Approximate phase

diagrams were developed in this manner simply by

using linear composition-property equations. It follows from this method that boundaries between

primary phases are straight lines and that three

such property planes may intersect in an invariant

point for ternary systems. It must be emphasized

that development of an approximate phase diagram

in this manner is not meant to replace the well- established phase equilibrium methods of Gibbs

[26], Morey [27], and others. This quantitative

analytical method [3] has two important uses: (1) Formulation of glass compositions for specific

property applications, (2) Furnishing first-approximation information on incomplete or nonexistent

phase diagrams of silicate glass systems.

30
A modified procedure has been used for the

ternary barium silicates since phase diagrams do

not exist for most of these systems. The glasses have

been segregated into groups within which the data can be quantitatively represented by linear equations. This procedure made it necessary to adopt an

arbitrary criterion for the grouping of glasses. In terms of intended usage of the data and the precision

of the measurements, it was decided that the standard error for refractive index for a given group be

limited to 0.001. This criterion resulted in placing

71 percent of the glasses in groups which can be

referred to here as "compatibility groups." The

differences between measured and calculated

values, of the other 29 percent, were 0.0020 or

greater and were arbitrarily left out of the computerized groups. The interested reader will, of course, draw his own conclusions in this regard and use the

measured data and computerized information to fit his own particular needs.

It is pointed out that refractive index, partial

dispersions and specific volume are properties of

the glasses, but that the f-value, and its inverse, the

dispersive power, are empirical ratios. These

properties are linear functions of mole compositions,

but the ^-values are not. Linear equations repre- senting v-values are only first approximations and

are shown here for estimation purposes only.

It is also to be noted that the previous work [3]

involved a larger number of glasses within groups

than were available for the barium silicate glasses.

The compositions were chemically analyzed while

the barium silicate compositions are calculated from

batch compositions. It is to be expected, therefore,

that the placement of glasses in given groups and

the boundaries between groups will be somewhat

less definite in the case of the barium silicate glasses. However, the composition-property information on the barium silicates is quite good enough for the formulation of glasses. As a practical matter

the refractive index of a glass depends on the

composition, the homogeneity, and the annealing

treatment. The determination of the refractive

index is dependent upon the precision and accuracy

of the measurement process and the environmental

conditions of measurement. Unfortunately, annealing procedures cannot be specified quantitatively,

and depending on the glass composition in question,

may cause differences in the third decimal place

in refractive index. To achieve greater precision, say in the fourth or fifth decimal places as in the case of commercial optical glasses, it is necessary

to pay much closer attention to all the factors in- fluencing refractive index.

Detailed information on analytical representation

of data in the barium silicates is shown in the follow- ing sections. Tables 8 to 13 give property-composition equations. Figures 44 to 51 are graphical plots of the derived composition-property relations.

4.1. The BaO-Ti02 -Si02 System

Table 8 shows equations relating compositions

and properties of glasses in the two compatibility

groups in this system. Equations for the partial

dispersions are obtained simply by taking differences

between the respective refractive index equations.

A given partial dispersion may be calculated either

by using the partial dispersion oxide factors or by

calculating each refractive index and taking

differences between the two. The same value will be obtained in the two cases. Calculated values of

v are only first approximations.

Table 8. BaO-Ti0 2 -Si0 2 glasses

Glass Property = /< SiO, + B Ti02 + C BaO

Property A B C Std. Error

Group I Glasses

nc 1.47915 2.27530 1.84290 0.00066 no 1.48163 2.29497 1.84628 .00062 nF 1.48594 2.34396 1.85834 .00070 ny — ni) 0.00431 0.04899 0.01206 no — nc .00248 .01967 .00338

Tli — tic .00679 .06866 .01544

V 60.06 -43.03 41.56 .4418 Volume 0.36089 0.23177 0.08893 .00078 Average of differences between measured and calculated

densities = 0.096

Group II Glasses

tic 1.48429 2.32814 1.79030 0.00116

tin 1.48553 2.35228 1.79234 .00119

n,. 1.48783 2.41798 1.79543 .00127

Tly — Tli, 0.00230 0.06570 0.00309

tlD — tic .00124 .02414 .00204

rtf — nc .00354 .08984 .00513

V 41.27 -10.73 49.93 0.1633 Volume 0.34946 0.25306 0.09806 .00027 Average of differences between measured and calculated

densities =0.003

Figure 44 shows compositions of glasses used in the two computerized groups. The position of the

boundary between the two groups, shown as a broken line, was obtained by solving the following

equations simultaneously

I nD = 1.48163 Si02 + 2.29497 Ti02 + 1.84628 BaO

II nD = 1.48553 Si02 + 2.35228 Ti02 + 1.79234 BaO

Si02 + Ti02 + BaO = 1

Solutions and calculation checks are as follows

SiO. 0.35 Si0 2 0.55 TiO> .30 Ti0 2 .20 BaO • .35 BaO .25 nD (I) 1.8533 1.7354 n„ (II) 1.8529 1.7356

31
o

2O

HO

<

tr

1

1

1 1

1 1

uuu i i U2

1

- S1O2

1

1

1

1

.40 — —

1 3 4 145 — o o -

138 146

.30 — ^ O o —

v. 95 147

•*« ~

v. O

40 ^ ^

.20 X

v. GROUP I •v. 142 49

X X —

143 35

.10 — X X —

— 152

X

0 1

1

1 .35 .45 .55 MOLE FRACTION SiO?

Figure 44. Compositional plot showing the groups into which

glasses in the BaO-TiO-rSiOa system were divided by computer

evaluation of property data.

Numbers of glasses in each group are those from earlier composition tables with F omitted.

The averages of differences between measured and

calculated densities (reciprocals of the specific

volumes) are shown in the tables. Representation of the data in terms of linear

equations permits arranging the information in a number of ways. Figure 45, for example, shows

lines of equal no in a Si0 2 -TiO:> plot. It will be

noted that the equal property fines are continuous

across the boundary between the two groups.

Similar plots can be made of equal values of partial

dispersions and specific volume. Plots showing

lines of equal density can be made, but they will

MOLE FRACTION SiO

Figure 45. Isofracts in the BaO-Ti02 -Si02 system.

not be quite linear. Figure 46 shows lines of equal v

in a Si02-Ti02 plot. As previously mentioned, v is an empirical ratio and the lines of equal value are not continuous across the boundary.

Reference to partial phase diagram information

by Rase and Roy [6] and by Cleek and Hamilton

[4] suggests that glasses in Group I may lie in the

BaO • 2Si0 2 phase field and those in Group II may

lie in the BaO •Ti0 2

- Si0 2 phase field.

32
.35

BaO -Ti02 - Si02 Nu VALUE

.45 .55 MOLE FRACTION SiOg

FIGURE 46. Lines ofconstant v in the BaO-TiO>-Si02 system.

4.2. The BaO-La,0,-SiO, System

Table 9 shows equations representing data in the two groups of glasses in this system. It will be

noted that I^Os has negative volume factors in both groups. The volume equations represent the

density data quite closely.

Figure 47 shows compositions of glasses used in the computerized groups. Information on this system

does not permit calculating the exact location of the

broken line separating the two groups It is drawn

roughly to denote the separation. That glass F549

is in Group I and glass F530 in Group II is verified by the following differences between measured

and calculated no when equations for the two groups

are used

Group I Group II

F530 0.0023 0.0002 F549 .0004 .0039

Table 9. BaO-La2 0.vSi02 glasses

Glass property = A SiOi + B Laid + C BaO

Property A B C Std. Error

Group I Glass es

n, 1.48825 nD 1.49036 n? 1.49538

n t -n„ 0.00502 nD -nc .00211 n F -n, .00713

v 63.00 Volume 0.35428 Average of differences

densities = 0.009

2.51281 2.52380

2.55158 0.02778

.01099

.03877

6.90 -0.17875

between

1.83983 1.84518

1.85810 0.01292

.00535

.01827

41.88 0.10807 measured ar

0.0(1068 .00068 .00070

0.0913

.00076

calculated

Group II Glasses

nc

id

nF ny — nn

ni, — nc

n F — n c vVolume

Average of

densities =

1.51660

1.51872

1.52372 0.00500

.00212

.00712 63.54 0.32645

differences

: 0.005

2.46619

2.47735 2.50559

0.02824

.01116 .03940

5.35 -0.10865

between

1.79980

1.80510

1.81819 0.01309

.00530

.01839 40.78 0.14791 measured and

0.00037

.00039 .00039

0.0965

.00030

calculated

.08

u .06

.04

.02

BaO -La 2 03-Si02

545 554

X X

553 539 O O

530

GROUP I

538 552 x x

527 563 O o536

GROUP n

561O

559 |549 518 O x XX I 634

.50 .55 .60 .65 MOLE FRACTION Si0 2

.70 .75

FIGURE 47. Compositional plot showing the groups into uhich

glasses in the BaO-L^GvSiO;, system were divided by computer

evaluation of property data.

Numbers of glasses in each group are those from earlier composition tables with F omitted.

33
4.3. The BaO-Ta2 05 -Si02 System

Table 10 shows equations representing data in the three groups in this system. It will be noted

that Ta^O.-, has negative v in all groups and negative

volume factors in groups I and II. Figure 48 shows compositions of glasses used in the computerized groups. The data are not sufficient

to allow calculation of the boundaries between the

three groups. The broken lines roughly indicate

the separations. Calculation of tin for the four

glasses near boundaries, F588, F534. F592, and F542

indicates that the glasses have been correctly

grouped. The following indicates differences

between measured and calculated tin using the

indicated equations:

Table 10. BaO-Ta205-Si02 glasses

Glass property=A Si02 + B Ta2 Os + C BaO

Glass Property A B C Std. Error

Group I Glas ses

nc 1.43819 2.68156 no 1.43974 2.70166 nF 1.44331 2.75161 nF - n[> 0.00357 0.04995 no-Tic .00155 .02010

raF -nc .00512 .07005

v 65.77 -96.27

Volume 0.37394 -0.34930

Average of differences between

densities = 0.007

1.95482 1.96134

1.97761 0.01627

.00652

.02279 34.13 0.06008 measured ;

0.00028

.00028

.00028

0.2208

.00077

calculated

Group II Glasses

nc 1.50395 2.48739 n„ 1.50627 2.50586 nF 1.51030 2.57296 nF -nD 0.00463 0.06710 nD -nc .00172 .01847 nF -nc .00635 .08557

v 59.09 -85.41

Volume 0.31595 -0.16059

Average of differences between

densities = 0.010

1.85520

1.86048

1.87262 0.01214

.00528

.01742 47.28 0.14165 measured and

0.00048

.00048

.00045

0.4249

.00071

calculated

Group III Glasses

nc 1.65915 2.31775 1.69455 0.00003

no 1.66596 2.33911 1.69456 .00000 nF 1.67132 2.36772 1.70992 .00004

n F — no 0.00536 0.02861 0.01536 no —nc .00681 .02136 .00001 nF — nc .01217 .04997 .01537

V 50.87 -12.64 46.87 0.2008 Volume 0.24761 0.02726 0.19721 .00009 Average of differences between measured and calculated

densities = 0.002

Group I Group II Group III

F588 0.0001 0.0026 F534 .0026 .0006 F592 .0001 0.0014 F542 .0028 .0000

1 1

1

1

1 i

i i BaO -Ta2 05 -SI02

1

1 1

593

.10 - 1 O

\ -

\

\

\

1

1

1 .08

\

615 592

1

1

cr Q "3 COO 1 583 582 • • Vo O O

| 604 \

\

1 .06 — \ group m ,\ GROUP n 1

1 —

581 * 535 534i 532 579 • •» O O O X X

542

\

580 | \ .04 1

1

1 GROUP I

1'588 576 522

.02 lx X XX —

1

1

531

0 i i1 1

1 1 .45 .50 .55 .60 MOLE FRACTION Si0 2

.65 .70

Figure 48. Compositional plot showing the groups into which

glasses in the BaO-Ta2 05 -Si02 system were divided by computer

evaluation of property data.

Numbers of glasses in each group are those from earlier composition tables with F omitted.

4.4. The BaO-ZnO-Si02 System

Table 11 shows composition-property equations

for glasses in the five groups in this system. This

table identified glasses placed in the different groups. Figure 49 gives compositions of the 57

glasses used in the evaluations. The broken lines serve to separate the five groups. Exact composition

locations of the boundaries could not be calculated. The equations indicate that the property contributions of ZnO and BaO, in terms of their factors, are

similar quantitatively. In this connection, all 57

glasses were run as one group on the computer. The

resulting no equation in this case was nn= 1.47000

Si0 2 + 1.81955 ZnO + 1.87614 BaO with a standard

error of 0.00205. Differences between measured and

calculated ni> ranged from —0.0073 to 0.0038. However, the range of standard errors for ni> for the five separate groups from 0.00048 to 0.00064 indicates

proper placement of the glasses. The interested

reader can determine by calculation that ni> values,

for example, of glasses not used in groups, have

measured minus calculated differences greater

than 0.001.

34
Table 11. BaO-ZnO-Si02 glasses

Glass property = A SiO; + B ZnO + C BaO

Glass A B C Std. property Error Group I Glasses: a 705, 698. 706. 707, 727, 693, 694, 702, 709,

728, 695

703. 710, 730. 712. 718, 731, 784, 714, 766, 713

nc 1.46539 1.80155 1.88253 0.00065

in 1.46731 1.80723 1.88812 .00064 m 1.47172 1.82073 1.90237 .00064

ny — fin 0.00441 0.01350 0.01425

ni) — ri( .00192 .00568 .00559

nt —n< .00633 .01918 .01984

V 64.55 33.86 39.39 0.1057

Group II Glasses: 809, 813, 803, 802, 801, 797, 798. 806, 842

804, 839, 807. 799, 755

nc 1.46248 1.81986 1.88284 0.00056 nD 1.46422 1.82590 1.88864 .00057

m- 1.46800 1.84130 1.90279 .00058

Uy — Til) 0.00378 0.01540 0.01415

no — nc .00174 .00604 .00580 iip—nc .00552 .02144 .01995

V 63.73 32.00 42.13 0.1076

Group III Glasses: 733, 734, 794, 735, 841, 795, 840

nc 1.52488 1.74916 1.74302 0.00047

ni> 1.52747 1.75428 1.74696 .00048

nh 1.53373 1.76683 1.75636 .00050

nh — nn .00626 .01255 0.00940

no — nc .00259 .00512 .00394

ny — nc .00885 .01767 .01334

V 58.21 37.56 55.81 0.0833

Group IV Glasses: 745, 721, 724, 754, 723, 722, 775, 720, 715

nc 1.49409 1.84200 1.80081 0.00051 nD 1.49602 1.84844 1.80587 .00051 nF 1.50064 1.86444 1.81811 .00053

nf

- — nu 0.00462 0.01600 0.01224

no — nc .00193 .00644 .00506

ny — nc .00655 .02244 .01730

V 63.29 28.97 45.02 0.0827

Group V Glasses: 760. 786, 787, 764, 762, 788

nc 1.46984 1.75656 1.89008 0.00056

no 1.47139 1.76190 1.89640 .00056

nf 1.47458 1.77476 1.91280 .00056

ny — nn 0.00319 0.01286 0.01640

nu — n<- .00155 .00534 .00632 nF — nc .00474 .01820 .02272

V 69.07 38.17 30.43 0.0652

a Numbers of Glasses in each group are those from earlier composition tables with F omitted.

4.5. The BaO-Nb2 05 -Si02 System

Table 12 gives equations for glasses in the two

groups in this system. It will be noted that v values

for Nb 2 0.-, are negative.

.40

.35

.25

.20

.10

.05

o o o o o

O O I group n o '

/ o o o o / \\ o ' \ o / • \ / A A \ /

BoO - ZnO - SiO?

AAA \

group m

\

GROUP nz \ •N V- _A_ A A A \

\ —

\

A A \x x X 5T - \ #

GROUP 3T

x x GROUP I X X

X X

X X

X \

\

\

X \

.50 .55 .60 .65 MOLE FRACTION Si0 2

.70

Figure 49. Compositional plot showing the groups into which

glasses in the BaO-ZnO-SiO-2 system were divided by computer

evaluation of property data.

Figure 50 shows compositions of glasses used in the two computer groups. The position of the

boundary between the groups, indicated by a broken

line, was determined by solving the following

equations simultaneously

I nD = 1.49408 Si02 + 2.80691 Nb2 05 + 1.85111 BaO

II nD = 1.56558 Si02 + 2.69145 Nb2 05 + 1.78584 BaO

Si02 + Nb2 05 + BaO=l

Solutions and calculation checks are as follows

SiO. 0.477 0.516 Nb,0, .100 BaO .523 .384 nod) 1.6808 1.7624

n„(\l) 1.6808 1.7627

35
Table 12. BaO-Nb2 05 -Si02 glasses

Glass property = A Si0 2 + B Nb2 05 + C BaO

Glass A B C Std. Error

property

Group I Glasses

Tie 1.49209 2.78035 1.84569 0.00053

nil 1.49408 2.80691 1.85111 .00053 n F 1.49870 2.87595 1.86462 .00055

n F — rii) 0.00462 0.06904 0.01351 no~nc .00199 .02656 .00542

n F — nc .00661 .09560 .01893

V 59.38 - 103.22 43.03 0.3705

Group II Glasses

Tic 1.56263 2.66145 1.78253 0.00112 in 1.56558 2.69145 1.78584 .00110

Tip 1.57170 2.77114 1.79431 .00109

n F — nn 0.00612 0.07969 0.00847 nn — nc .00295 .03000 .00331 n F — nc .00907 .10969 .01178

V 42.36 -35.25 47.86 0.3004

.20

uj .10

.05

o o

1466 1465 BaO - Nb205 -Si02

1462 1461 1460 1459 O O O O

GROUPH

1457 1451 O O

1450 1449 O O

1446 O

/

/ 1443 1442

/ x x

I

GROUP I

1439 1437

X

1434 1433 1432

.35 .45 .55 MOLE FRACTION Si0 2.65

Figure 50. Compositional plot showing the groups into which

glasses in the Ba-Nb2 05-Si02 system were divided by computer

evaluation of property data.

Numbers of glasses in each group are those from earlier composition tables with F omitted.

4.6. The BaO-Al2 03 -Si02 System

Table 13 gives composition-property equations for the two groups of glasses in this system. Phase

diagrams for this ternary system and the three

binary systems have been published [23, 24, 25]. Figure 51 is a mol fraction plot converted from

published diagrams 210 and 556 [23]. This figure

shows the compositions of glasses used in computerized groups. Glasses situated in the solid solution area of BaO • 2Si0 2 and 2BaO • 3Si02 were placed

in Group I. Those in the BaO • ALO.j 2SiC>2 primary phase field were placed in Group II. In each

case the criterion, previously mentioned, for "compatibility groups" was adhered to. Location

of the boundary between the two groups cannot be

calculated exactly as was the case in some of the

other systems.

Table 13. BaO-Al2 03 -Si02 glasses

Glass Property = A Si02 + B A120:, + C BaO

Property A B C Std. Error

Group I Glasses: ' 1131, 1132, 1133, 1164, 1165, 1166

Solid Solution of BaO 2Si02 and 2BaO • 3Si02 nc 1.56751 1.38164 1.75764 0.00029

ni> 1.57129 1.37834 1.76167 .00032

Tly 1.57893 1.38051 1.77168 .00032 nF — nn 0.00764 0.00217 0.01001 np — nc .00378 -0.00330 .00403 nF — nc .01142 -0.00113 .01404

V 50.05 95.47 53.80 0.2210

Group II Glasses: 1143, 1123, 1128, 1129, 1130, 1196, 1197, 1198,

1210, 1207, 1211, 1209, 1208 BaO Al2 Os 2Si02 Primary Phase

nc 1.48964 1.57531 1.82391 0.00074 nn 1.49166 1.57848 1.82924 .00075 nF 1.49601 1.58578 1.84299 .00076 np — nn 0.00435 0.00730 0.01375 nu- nc .00202 .00317 .00533 nc— nc .00637 .01047 .01908

V 66.90 55.62 36.61 0.2063

a Numbers of Glasses in each group are those from earlier composition tables with F omitted.

Previous work [3] has indicated that oxide factors

for refractive index are characteristic of the primary

phase field involved. For example, the ni> factors for Si02 in Si02 fields (particularly cristobalite and

tridymite) is reasonably close to 1.458, the refractive

index nn for fused silica. Likewise the specific

volume factor for such glasses corresponds to a density of 2.20 approximating the density of fused

silica. The tin factor of 1.57848 for glasses in Group

II is reasonably close to those found for AI2O3 in other glass systems [3]. However, the 1.37834 ni> factor for AI2O3 for glasses in Group I is low and

suggests the need for more data in this area.

36
HOLE FRACTION

FIGURE 51. Triangular plot showing the phase fields and groups

into which glasses in the BaO-Al^Oii-SiOi; system were divided by computer evaluation of property data.

5. Formulation of Glasses for Specific

Optical Applications

The glass technologist and optical designer can

use the foregoing quantitative relations between

glass compositions and properties to calculate

compositions having desired optical properties.

The use of this method [3] must be based on reliable experimental data. The data shown in this report

are considered to meet this criterion. The method

can best be understood by outlining examples of its use. 5.1. Example One

Values of ni> in Group I TiO^ glasses can be

determined using the equation: no— 1.48163

Si02 + 2.29497 Ti02 + 1.84628 BaO. Consider glass

F35 having a calculated n«= 1.67236. It is desired

to increase the index by 0.0050. This can be done

in three ways: (1) substitution of Ti02 for SiO^,

(2) substitution of BaO for SiGv. or (3) substitution

of Ti02 for BaO. Differences between factors for these substitutions are respectively 0.81334, 0.36465,

and 0.44869. The composition change for the first substitution is 0.0050/0.81334 = 0.0061 TiO> for Si02 . The others are determined in the same

manner. The following table shows compositions

and calculated values for «», mean dispersion

nF — tie, v, and densities for the four glasses.

F35 (1) (2) (3)

Si02 0.6000 0.5939 0.5863 0.6000 TiO. .1000 .1061 .1000 .1111 BaO .3000 .3000 .3137 .2889 nD 1.67236 1.67732 1.67736 1.67734

rtf — iir 0.01558 0.01594 0.01569 0.01616

V 44.20 43.57 43.95 43.27 Density 3.754 3.765 3.807 3.732

5.2. Example Two

Consider glass F1432 in Group I Nb2 0.-, glasses

which has a measured ni> of 1.63471. It is desired

to calculate the exact composition having this index value. Since it contains three oxides one must

be fixed arbitrarily. Assume that SiO2 = 0.66. The

solution is obtained by solving these equations

simultaneously:

n„= 1.49408 SiO. + 2.80691 Nr»05 + 1.85111 BaO

Si02 + Nb205 + BaO = l

Then; 1.63471 = 1.49408 (.66) + 2.80691 Nb20.-,+

1.85111 (0.34 -Nb2 0.-,)

Glass F1432

Calculated

Si02 0.6600 0.6600 NbsOa .0200 .0201 BaO .3200 .3199 no 1.63471 1.63468

rip — nc 0.01241 0.01234

V 51.10 50.87 (Measured values for F1432 are from

table 6)

5.3. Example Three

Glass F583 in Group II Ta2 Os glasses has a measured mean dispersion of 0.01612. Calculate

the exact composition assuming SiO 2 = 0.53. The

answer is obtained from the equation:

0.01612 = 0.00635 (0.53) + 0.08557 (0.47 - BaO)

+ 0.01742 BaO

F583 Calculated

(Table 4)

SiO 2 0.5300 0.5300 Ta205 .0700 .0670 BaO .4000 .4030 n„ 1.71844 1.71598 n t — n< 0.01612 0.01612

V 44.60 44.65 Density 4.703 4.678

5.4. Example Four

Glass F553 in Group II La2 0.j glasses has a measured density of 4.387 (volume = 0.22795).

Assume SiO 2 = 0.55 and calculate exact composition. The solution is given by: 0.22795 = 0.32645

(0.55) -0.10865 La.O;, + 0.14791 (0.45 - La2 0:,)

37
F553 Calculated

(Table 3)

Si0 2 0.5500 0.5500 La2 03 .0700 .0708 BaO .3800 .3792 Density 4.387 4.387 «D 1.69496 1.69519

rif — nc 0.01369 0.01368

V 50.80 50.79

5.5. Example Five

Figure 45 shows lines of equal nn in the Ti0 2 glasses and figure 46 shows lines of constant v in this system. Superposition of these two figures

indicates that the 1.75 rtu line crosses the 35 v line

in Group I. However, the 1.75 tin line crosses the 30

v line in Group II glasses. Calculate the two

compositions.

(a) Composition of the glass having an Tin of 1.75 and a v of 35 is obtained by solving the following

equations simultaneously:

1.75=1.48163 SiO. + 2.29497 (l-SiO .-BaO)

+ 1.84628 BaO

35 = 60.06 SiO >- 43.03 (l-SiO,-BaO)

+ 41.56 BaO

The composition is found to be: SiO, 0.4918

TiO, .1851 BaO .3231 A check calculation shows the values as 1.75000

and 35.01.

(b) Composition of the glass having an no of 1.75 and a v of 30 is obtained by solving the equations:

1.75 = 1.48553 Si02 + 2.35228 (1 - Si02 - BaO) + 1.79234 BaO

30 = 41.27 SiO,

-10.73 (1-SiO,- BaO) + 49.93 BaO

The composition is:

Si02 0.5852

TiO. .2450

BaO .1698

A check calculation gives the values as 1.74998

and 30.00.

6. Summary

The areas of glass formation in the following ter- nary oxide systems have been determined:

BaO-Ti02 -Si02 BaO-La2 03 -Si02

BaO-Ta2 05 -Si02 BaO-ZnO-Si02 BaO-Nb2 05 -Si02 BaO-Al2 03 -Si02

Property measurements, including sag point, re- fractive index and dispersion, liquidus temperature,

and infrared transmittance, were made on the

resulting glasses. In addition, composition-property

data were evaluated to develop quantitative rela- tions for use by glass technologists in formulating

glasses having specific property values.

The writers wish to thank John A. Moore, who

melted the experimental glasses; Thomas G. Scuderi, who helped in making the property

measurements; and I. H. Malitson, who made the

refractive index measurements.

7. References

[1] Spinner. Sam, Cleek, Given W., and Hamilton, Edgar H., Determination and use of the sag point as a reference

point in the heating of glasses. J. Res. Nat. Bur. Stand.

(U.S.). 59, No. 3, 227-231 (Sept. 1957) RP2791.

[2] Grauer, Oscar H.. and Hamilton, Edgar H., An improved

apparatus for the determination of liquidus temperatures and rates of crystal growth in glasses. J. Res. Nat. Bur. Stand. (U.S.), 44, 495-502 (May 1950) RP2096.

[3] (a) Babcock, C. L., Substructures in silicate glasses, J. Amer. Ceram. Soc. 51, 163 (1968);

(b) Babcock, C. L., Substructure classification of silicate glasses. Ibid. 52,151 (1969).

[4] Cleek, Given W., and Hamilton. Edgar H., Properties of barium titanium silicate glasses. J. Res. Nat. Bur. Stand.

(U.S.), 57, No. 6, 317-323 (Dec. 1956) RP2720.

[5] Phillips, C. J., Glass the miracle maker, p. 120 (Pittman

Publishing Corp., 1948).

[6] Rase, D. E., and Roy. Rustum. Phase equilibria in the sys- tem BaO-Ti02 , J. Am. Ceram. Soc. 38, 102 (1955).

[7] (a) Bunting. E. N., Phase equilibria in the systems Ti0 2 , Ti02 -Si02 and Ti02 -Al2 03 , J. Res. Nat. Bur. Stand. (U.S.),11,719(1933)RP619;

(b) Ricker, T. W., and Hummel. F. A., Reactions in the sys- tem Ti02 -Si02 ; revision of the phase diagram, J. Am.

Ceram. Soc. 34, 271 (1951);

(c) DeVries, R. C, Roy, Rustum. and Osborn, E. F., The

system Ti02 -Si02 , Trans. Brit. Ceram. Soc. 53 , 525

(1954).

[8] (a) Eskola, P., The silicates of strontium and barium, Am.

J. Sci. 5th series, 4, 331 (1922);

(b) Grieg. J. W., Immiscibility of silicate melts, Am. J. Sci.. 5th series. 13, 1(1927).

[9] Rase, D. E., and Roy. Rustum. Phase equilibria in the sys- tem BaTiGvSiO,, J. Am. Ceram. Soc. 38, 389 (1955). Correction: Ibid. 39, 120 (1956).

[10] Hamilton, Edgar H., and Cleek, Given W.. Shape of the liq- uidus surface as a criterion of stable glass formation.

J. Res. Nat. Bur. Stand. (U.S.), 60, No. 6, 593-596 (June

1958) RP2872.

38
[11] Hubbard, Donald, and Hamilton, Edgar H., Studies of the chemical durability of glass by an interferometric method,

J. Research J. Res. Nat. Bur. Stand. (U.S.), 27, 143-157

(Aug. 1941)RP1409.

[12] Hubbard, Donald, Hygroscopicity of optical glasses as an

indicator of serviceability, J. Res. Nat. Bur. Stand. (U.S.), 36, 365-375 (April 1946) RP1706.

[13] Saunders, James B., An apparatus for photographing inter- ference phenomena, J. Res. Nat. Bur. Stand. (U.S.), 35, 157-186 (Sept. 1945) RP1668.

[14] Levin, Ernest M., Robbins, Carl R., and McMurdie, Howard

F., Phase diagrams for ceramists. Figure 209, American

Ceramic Society (1964).

[15] Bunting, E. N., Phase equilibria in the system Si02-ZnO,

J. Res. Nat. Bur. Stand. (U.S.), 4, 131-136 (1930) RP136.

[16] Roth, R. S., and Waring, J. L., Phase relations in the binary

system barium oxide-niobium pentoxide. J. Res. Nat.

Bur. Stand. (U.S.), 65A (Phys. and Chem.), No. 4, 337-344

(July- Aug. 1961).

[17] Ibrahim, M., and Bright, N.F.H., The binary system Nb2 05

- Si0 2 , J. Amer. Ceram. Soc. 45 [5], 221 (1962).

[18] Morey, G. W., Properties of glass, 2nd Edition (Reinhold

Publishing Corp., New York, N.Y., 1954), p. 75.

[19] Scholes, S. R., Modern Glass Practice (Industrial Publications, Inc., Chicago, 111. 1941), p. 48.

[20] Morey, G. W., Properties of glass, 2nd Edition (Reinhold

Publishing Corp., New York, N.Y., 1954), p. 85.

|21| Kawson, H., Inorganic glass-forming systems (Academic

Press, London, 1967), p. 199.

[22] Stanworth, J. E., Physical properties of glass (Oxford al i In Clarendon Press, Oxford, 1950), p. 5. [23] Levin, Ernest M., Robbins, Carl R., and McMurdie, Howard

F., Phase diagrams for ceramists, Figures 556 and 557, American Ceramic Society (1964).

[241 Thomas, Robert H., Phase equilibrium in a portion of the ternary system BaO-Al2 03-Si02 , J. Amer. Ceram. Soc. 33,35(1950).

[25] (a) Lin. H. C, and Foster, W. R., System BaO-Al2 03

- SiGv I Amer. Mineral. 53 [1-2], 134 (1968);

(b) Foster, W. R„ and Lin, H. C, System BaO-Al 2 0,- Si0 2 : II Amer. J. Sci. 267A, 134 (1969);

(c) Lin, H. C, and Foster, W. R., System BaO-Al2 0 ,-SiGv

III Mineral, Mag. 37 [288], 459 (1969);

(d) Semler, C. E., and Foster, W. R., System BaO-Al.,0 ,- SiGv IV J. Amer. Ceram. Soc. 52 [12], 679 (1969);

(e) Lin, H.C., and Foster, W. R., System BaO-AI 2 0.,-Si0 2 : VJ. Amer. Ceram. Soc. 53 [10], 549 (1970);

(f) Semler, C. E., and Foster, W. R., System BaO-Al 2 Gv

SiO,: VI J. Amer. Ceram. Soc. 53 [11], 595 (1970).

[26] Gibbs, J. W., The Scientific Papers of J. Willard Gibbs,

(Longmans Green, New York, 1906).

[27] (a) Morey, G. W., Section G in Commentary on the Scientific Writings of J. Willard Gibbs (Yale University Press,

1936);

(b) Morey, G. W., The Properties of Glass (Reinhold, New

York, 1954).

39
form NBT-114A (1-71) U.S. DEPT. OF COMM. BIBLIOGRAPHIC DATA

SHEET

1. PUBLICATION OR REPORT NO. NBS-MN-135

2. Gov't Accession No.3. Recipient's Accession No.

4. TITLE AND SUBTITLE

PROPERTIES OF IN SOME TERNARY SYSTEMS CONTAINING

BaO AND SL02

5. Publication Date September 1973

6. Performing Organization Code

7. AUTHOR(S)

G.W. Cleek and C.L. Babcock

8. Performing Organization

9. PERFORMING ORGANIZATION NAME AND ADDRESS

NATIONAL BUREAU OF STANDARDS

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

10. Project/Task/Work Unit No.

11. Contract/Grant No.

12. Sponsoring Organization Name and Address

Same as 9.

13. Type of Report & Period Covered

Final

14. Sponsoring Agency Code

15. SUPPLEMENTARY NOTES

16. ABSTRACT (A 200-word or less factual summary of most significant information. If document includes a significant

bibliography or literature survey, mention it here.) The glass forming regions in six ternary oxide systems containing BaO, Si02

and a third oxide have been determined. The properties of the resulting glasses

were measured and the results are reported. The data on refractive indices, dispersions and specific volumes were evaluated by computer methods in an attempt to

identify "substructures" containing the cations present in the glasses.

17. KEY WORDS (Alphabetical order, separated by semicolons)

Barium glasses; barium silicates; glass properties; glass property factors;

oxide glasses; silicate substructures; ternary glasses.

18. AVAILABILITY STATEMENT

E UNLIMITED.

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19. SECURITY CLASS

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