EA-07

Influence of fluorine on weatherability in sulfophosphate glass(Nippon Electric Glass Co., Ltd) ○S. Konoshita

Weatherability of almino-sulfophosphate glass with various content of fluorine substituted for oxygen wasinvestigated. By analyzing short range structure with Raman spectroscopy and X-ray photoelectron
spectroscopy, it is suggested that fluorine is preferentially bonded to Al3+, and then bonded to P5+ inalmino-sulfophosphate glass. The weatherability of almino-sulfophosphate glass is drastically deteriorated
by formation of PF bond.
e-mail: skonoshita@neg.co.jp
IntroductionSulfophosphate glass has ionic structure, consisting of mainly Q1 and Q0. By the structure, sulfophosphateglass shows high chemical durability and low glass transition temperature compared to phosphate glass[1-3].
In general, the incorporation of fluorine into phosphate glass conducts depolymerization of the network bybreaking phosphate chains[4] and it could cause the increase chemical durability. This work is focused on arelationship between weatherability and short-range structure of almino-sulfophosphate glass with varied
fluorine content.
Experimental
Almino-sulfophosphate glasses, 18Na2O-xZnF-(45-x)ZnO-1Al2O3-9SO3-27P2O5、x=0, 6, 8.4, 11, 17, 23
were prepared by using reagent-grade of ZnSO4, ZnF, Na2PO4, and Na2O. The batches were mixed andmelted at 800oC for 1.5 hours in a platinum crucible in the air. The melt was casted on a glassy carbon plate,and annealed at 400℃ for 0.5 hours. 100g of transparent plate-like glass samples were obtained.
Compositions of the glass were analyzed by X-ray fluorescence spectroscopy (ZSM Primus Ⅱ, RigakuCo.Ltd.). Raman spectra and F1s Binding energy of the glass were measured by Raman spectroscopy(NFS-230HKG, JASCO Co. Ltd.) and X-ray photoelectron spectroscopy (PHI5000, ULVAC PHI, Inc.)
respectively. The F1s binding energy was fitted into two peak of P-F bond and Al-F bond by using
Gaussian distribution. Weathrability were tested by following procedure. The glass samples were also cut insize of 20×20×2mm and surfaces were polished. Surface state of the glass samples exposed to moisturein 90%RH, 60℃ for 720 hours were observed under microscope.
Results and discussionMicroscopic images of the glass surface after weatherability test are shown on Table 1. There are novisible change in x=0~8.4, clouded part is observed in x=11 and crystallization are observed in x=17 and23.
Table 1. Microscopic images of glass surface after weatherability test.

X=0

X=6

X=8.4

X=11

X=17

X=2360℃
90％
720 hFigure 1 shows the Raman spectra of glass. The peak near 850cm-1 assigned to the P-F bond [4] wasappeared at X=11 and the intensity increased with increasing X. Figure 2 shows F1s XPS spectra of theglass. The lower binding energy peak (~685.5eV) are assigned to F bonded to Al, and the higher binding
energy peak are assigned to F bonded to P[4]. The higher peak was appeared at x=11 and increased withincreasing X.

Intensity (a.u.)

It has been reported that F is preferentially bonded to Al in almino-phosphate glass [4,5]. It is estimatedthat P-F bonds fraction is considered to be F-4Al fraction defined as the value subtracted 4Al from F at%when it is assumed that P-F bonds are formed after the four sites around the six-coordinated Al3+ with two
bridging oxygen are occupied by fluorine. Figure 3 shows P-F bonds or AlF bonds fractions obtained fromXPS spectra versus F-4Al. P-F bonds fraction was not observed in -1 > F-4Al (X= ~8.4) and increased withincreasing F-4Al (X=11~) value. Coordination number of Al3+ seems to be lower than six because P-Fbonds are formed from F-4Al is below 0. The weatherability of glass is thought to be deteriorated byforming P-F bonds.
x=0
x=6Conclusions
x=8.4
The weatherability, Raman spectra and XPS ofx=11
almino-sulfophosphate glass series, 18Na2O- xZnFx=17(45-x)ZnO- 1Al2O3- 9SO3- 27P2O5, were investigated.
P-F
x=23
It has been found that weatherability of glass is related
to F-4Al value. Raman and XPS spectra suggest that F
is preferentially bonded to Al until six coordinated Al
are fully occupied then P-F bond are formed. Theformed P-F bonds deteriorate weatherability of glass.
700

900
1100
Raman Shift /cm-1

P-F

X=23
X=11
X=8.4
X=6
X=04
3.5
3
2.5
2
1.5
1
0.5
04
X=233
X=11
X=8.4
X=61
X=00-4.0

Figure 2. F1s XPS spectra of fluoro-sulfophosphateglass.

2-2.0

0.0
2.0
F-4Al (atomic%)

4.0

Figure 3. Quantitative fluorine bonding determinedfrom respective F1s spectra.

Reference
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[2]
[3]
[4]
[5]

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Fraction Al-F bonds × F

Al-F

Fraction P-F bonds × F

Figure 1. Raman spectra of fluoro-sulfophosphate glass.