NATIONAL BUREAU OF STANDARDS REPORT

10 441

Progress Report

on THE CRYSTAL STRUCTURE OF CaKAs0

4

-8H

2

0

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
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NATIONAL BUREAU OF STANDARDS REPORT

NBS PROJECT NBS REPORT

311.05-11-3110561 June 16, 1971 10 441

Progress Report

on THE CRYSTAL STRUCTURE OF CaKAs0

4

’8H

2

0

B. Dickens and W. E. Brown*

Institute for Materials Research

National Bureau of Standards

Washington, D. C. 20234

* Director, American Dental Association Research Unit,

National Bureau of Standards, Washington, D. C. 20234.

This investigation was supported in part by research grant DE00572

to the American Dental Association from the National Institute of

Dental Research and is part of the dental research program conducted

by the National Bureau of Standards, in cooperation with the American

Dental Association; the United States Army Medical Research and

Development Command; the Dental Sciences Division of the School of

Aerospace Medicine, USAF; the National Institute of Dental Research;

and the Veterans Administration.

NATIONAL BUREAU OF ST

for use within the Government, and review. For this reason, th< whole or in part, is not author Bureau of Standards, Washingtc

the Report has been specifically

IMPORTANT NOTICE

Approved for public release by the

Director of the National Institute of

Standards and Technology (NIST)

on October 9, 2015.

ss accounting documents intended

subjected to additional evaluation

listing of this Report, either in

e Office of the Director, National

jy the Government agency for which

:opies for its own use.

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

The Crystal Structure of CaKAs0 4 *8H g 0

Brian Dickens and Walter E. Brown*

Institute for Materials Research

National Bureau of Standards

Washington, D. C. 20234

Director, American Dental Association Research

Unit at the National Bureau of Standards,

Washington, D. C. 20234.

Abstract

CaKAs04 *8H2 0 crystallizes in the orthorhombic unit cell

a a* 7.146(1) A, b = 11.696(2) A, c = 7.100(2) A at 25°C with

cell contents of 2 [CaKAs04 *8H2 0] . The structure has been

refined to = 0.037, R = 0.043 in space-group Cm2m using

1023 observed reflections corrected for absorption. Allowance was made for anomalous dispersion and secondary isotropic

extinction.

All ions in CaKAs04 *8H2 0 are completely hydrated. Ca

i coordinates to eight water oxygens with Ca...O distances in

the range 2.459(5) A to 2.490(3) A. K coordinates to eight

o water oxygens with K. ..0 distances ranging from 2.746(3) A

o to 2.960(7) A. The coordination polyhedra of Ca and K share

a face of four water molecules. The oxygens of the As04 ion

are the acceptors in hydrogen bonds from 16 water molecules

and form no bonds with the cations. The two crystallographically

different As—0 distances in the As04

3 ” ion are 1.682(4) A and

o o 1.684(4) A when uncorrected for thermal motion, and 1.690 A

o and 1.692 A with the riding model correction.

The structure of CaKAs04 -8H2 0 is related to that of

MgNH4 P04

• 6H2 0, struvite. This structural type may be common

to several calcium phosphates and related compounds.
•J V i

'

/

'

.

*
The Crystal Structure of CaKAs04

* 8 H2 G

Introduction

In crystallization, nucleation is an important step

which could conceivably control the identities and forms

of materials that grow to macroscopic sizes. For various

reasons

1 studies of hydrates may give valuable clues to the

existence of possible precursors or nuclei of crystallization

in aqueous environments. In biological mineralization,

hydration of ions is likely to play a significant role, and

the formation of ion pairs or higher complexes may be important. We found in our study of CaC03 •6H2 0

1 that the

crystal structure contains [CaC03 ]° ion pairs which are completely hydrated. All Ca ions in CaC03 *6H2 0 are in ion pairs.

To examine the hydration of Ca and the possible retention in

the solid state of ion pairs involving X04 ions, in this case

ASO4

3 *”, we have determined the crystal structure of CaKAs04

* 8H2 0. Prior to this work, the formula was believed to be

CaKAs04

* 7H2 0. The related salts CaKP04 °8H2 0 and CaNH4 P0 4

• 8HS 0

were also prepared. The structure determination was carried

out on CaKAsQ4 *8H2 0 because it is the only one that is

sufficiently stable at room temperature. The salt CaNH4 As04

*

8H2 0 was not made.
- 2 - Data collection and structure refinement

CaKAs04 *H2 0 was prepared by mixing 20 cm

3 of 0.1 m’f” 1

CaCl2 solution, 25 cm

3 1.0 m*^” 1 tri-^potassium citrate solution

and 10 cm3 3.0 m’4” 1 KOH solution at 0°C and then adding

10 cm

3 0.2 m'f” 1 K2 HAs04 solution. The resultant mixture

was kept at 0°C; precipitation of CaKAs04 *8H2 0 began after

about 2 hours.

The crystal used in the data collection was an approximately square plate with dimensions 0.06 mm x 0.10 mm x 0.12 mm.

It was mounted on the goniometer head in our usual way

2

. Formula (ideal) : CaKAs04 *8H2 0

cell: orthorhombic

a = 7.146(1) A at 25°C

b = 11.696(2)

c = 7.100(2) o volume = 593.40 A

3

space-group Cm2m? cell contents 2 [CaKAs04 *8H2 0]

reciprocal lattice extinctions: h + k = 2n + 1 for hk£.

density calculated from refractive indices =2.10 g*crrT 3 3

density calculated from unit cell = 1.933 g*cm~ 3

. In general, the data collection and data processing procedure

given in reference 2 was followed. The 9-20 scans here

were carried out at 0.5°/min for 20. Each background was

counted for 40 sec. Absorption corrections were made assuming

p(Mo) = 39.6 cm” 1

. The maximum and minimum transmission factors

were 0.83 and 0.66, respectively. 2163 reflections were collected

from the hk£ and hk£ octants of the reciprocal lattice and were
-3

merged into a unique set of 1071, of which 1023 were "observed"

and 48 are "unobserved". "Unobserved" reflections are those

less than 2 a (I) above background.

The structure of CaKAs0 4 *8H2 0 was solved from a sharpened

Patterson map (calculated from the E

s -1 coefficients, where E

4

is the quasi-normalized structure factor ) and from subsequent

F 0 electron density syntheses. The scattering factors used

were those of the neutral atoms. They were taken from references 5 and 6 for the X-ray 67 7 refinements and from reference

8 for the refinements using the program RFINE, written by

L. W. Finger of the Carnegie Institute of Washington. The

structure with hydrogens excluded was refined isotropically

to Rw = 0.067, R = 0.068 using X-ray 67. The quantity minimized was Iw(F 0 - F c ) 8

. Unobserved reflections calculating

more than 2cr(F^^) above background were included. Three

cycles of anisotropic refinement varying all unconstrained

parameters decreased Rw to 0.054 and R to 0.056.

The hydrogen positions were found in a difference electron density synthesis calculated after the last cycle in this

refinement. The next largest peaks after the hydrogen atoms were

equivalent to about 1/2 of an electron between As and 0(1), and

about 1/3 of an electron at 0.5, 0.35, 0.25. Because of its

proximity to As and 0(1), the former peak cannot be attributed

to an atom. The latter peak is in a void in the structure,

but is, however, only 2.30 A from 0(5) and 2.39 A from 0(2).
-4

It is 2.30 A from H(3) and 2.65 A from K. Thus, because it does not seem to fill all the requirements

of any one chemical species, it is attributed to the

background.

The structure including hydrogen atoms with

with the hydrogen

variable positional parameters but ^thermal parameters

fixed at B = 1.0 A

2 was then refined anisotropically

to = 0.040, R = 0.047 in three cycles using Finger's

least-squares program RFINE. Correction was made for

secondary isotropic extinction. Although the environments of the oxygen atoms are not very different, the

surprising result that the two crystallographically

different As —0 distances in the As04 group were

1.664(4) A and 1.701(4) A was obtained. After correction for anomalous dispersion was included in the

refinement, the As —O distances became essentially

equal, as would be expected from consideration of their

similar environments. The values of f' and f" were

taken from Cromer9

. The parameters from the third

cycle (R = 0.037, R = 0.043) of this series of refinements are given in Table 1. (The values for equivalent

refinement of the other
-5-

enantiomorph are Rw * 0.049, R = 0.054.) The observed and

calculated structure factors are given in Table 2. The average shift/error in the last cycle was 0.19 excluding hydrogen

parameters and 0.35 for all parameters. The standard deviation of an observation of unit weight, [Iw ( |f0

| - |f c |

)

3 /

l. (1071 - 57)

]

2

, was 1.60. The largest correlation coefficient

was 0.41 between (B22 ,B12 ) of 0(4); all others were below

0.17. Because the isotropic secondary extinction parameter

refined to -0.00000100(7) cm, it was constrained to zero in

the final refinements. The physically unreasonable negative

value obtained may be due to small errors in the absorption

corrections

.

The space-group Cm2m requires the chemical formula to

contain an even number of water molecules unless there are

statistical vacancies in some of the water positions. The

thermal parameters of the oxygens of the water molecules are

fairly close to those of the oxygens in the As04 ions and

thus the formula is probably CaKAs04 *8H2 0 with no statistical

vacancies. To check this, a sample of CaKAs04 *8H2 0 was heated

quickly (<~1 min) to constant weight at 400° C; a weight loss

of eight moles of water per formula weight was obtained.
-6 -

Three sets of hydrogen positions , (i) from the difference electron density synthesis, (ii) from the least-squares

refinements, and (iii) calculated idealized positions, are

given in Table 3. All distances and angles involving hydrogen in the tables or the text were obtained using these

calculated hydrogen positions.

Description of the Structure

The structure of CaKAs0 4 is shown in Figure 1. The Ca

and K ions and the oxygen of the 0(4) water molecule lie on

mirror planes parallel to (001) . The As04 ions lie on

mirror planes halfway between these cation planes. The 0(3)

and 0(5) water molecules lie approximately halfway between

the cation planes and the anion planes. Also, mirror planes

containing both cations and anions and the oxygen of the 0(3)

water molecule exist parallel to (100)

.

All the ions in CaKAs0 4 *8H2 0 are completely hydrated,

and thus there are no direct bonds between ions themselves.

There are eight water molecules in the coordination polyhedra

of the Ca and K ions and 16 in the coordination polyhedron

of the As 0 4 ion. Each of the water molecules in the structure is bonded to
-7-

the Ca, K and As04 ions. The coordination polyhedra of Ca

and K share a face of four water molecules.

The Ca ion environment. —The environment of the Ca ion,

which lies on the intersection of two mirror planes, is

detailed in Table 4 and Figure 1. The Ca ion is coordinated

to eight oxygens of water molecules arranged in an approximately square antiprism. The range of Ca...O distances,

o o 2.459 A to 2.490 A, is unusually small and indicates strong

bonding to all these oxygens. The shortest 0...0 distance

in this polyhedron is 2.789 A for 0(3)... 0(4). All other

o 0...0 distances are a little over 3 A. The shortest Ca...O

distances are to the approximate square of water oxygens

0(3t , 3xr

, 4X

, 4

I=c:

) (Figure 1) , which is also part of the

K ion environment. However, these oxygens are the weakest

bonded to K. The longest Ca...O bonds are to those water

oxygens in edges common to the coordination polyhedra of Ca

and K. These oxygens, 0(5X , 5xr , 5XJ“i'

, S13") , are strongly

bonded to K though not as strongly as they are to Ca.

The K ion environment. —The details of the environment

of the K ion are given in Table 4 and Figure 1. K is bonded

to eight water oxygens arranged in a distorted square antiprism.
- 8 -

As would be expected, K is relatively far (2.918 A, 2.960 A)

from the coordination polyhedron face which involves water

oxygens 0(3

,

3^~) and 0(4J-D , 4

1-3-) (for K*~, Figure 1) and

which is shared with the Ca?'*' coordination polyhedron. The

»- © K

x ion instead forms stronger K. ..0 (2.746 A) bonds to the

0(5X

/ 5*. 5

3

, S

33-

) water oxygens in the opposite face of

the coordination polyhedron.

The edges of this face are also edges in the Ca coordination polyhedron. The shortest K...Ca distance, ^...Ca11"1 =

o 3.66 A, is along (010), across the shared face comprised of

water oxygens of types 0 ( 3r*-LJ

, 3

x=sr

) and 0(4T=r“r

, 4

312

) . The As04 group and its environment. —The details of the

As04 group and its environment are given in Table 5. The two

unique As-0 distances are not significantly different, which

is consistent with the lack of cations and very strong hydrogen bonds in their environments. The O-As-O angles across

the mirror planes are significantly different from the other

O-As-O angles. The reason seems to be that the hydrogen

bonds from the water molecules are strong enough to pull 0(1)

and 0(2) away from the mirror plane to angles greater than

the tetrahedral angle. (It has been our experience that

groups such as P04

^~

are easily distorted from tetrahedral
-9-

symmetry.) The 0(l)-As-0(2) angle of 107.5° is, therefore,

regarded as a concomitant result. The As04 group is extensively hydrogen bonded, 0(1) and 0(2) each being the acceptor

in four hydrogen bonds (Tables 5 and 6) . There is no

coordination between the As04 group and the Ca and K cations.

The environments of the water molecules. —The environments of the water molecules are detailed in Table 6. The

water molecules in Figure 1 and in the tables have the

idealized geometry 0-H = 0.958 A and ^H-O-H = 104.5°. The

hydrogen bonds were made as linear as possible in the calculation of the probable hydrogen positions. Water oxygens

0(3) and 0(4) lie on mirror planes; 0(5) is in a general

position. All the oxygens of the water molecules are bonded

to the Ca and K ions and all the hydrogens are hydrogen

bonded to the oxygens in the As04 group. There is no hydrogen bonding between water molecules. The 0(3) and 0(4) water

molecules are bonded strongly to Ca, less strongly to K,

and are the donors in hydrogen bonds of average strength to

0(2) and 0(1) of the As04 group. The 0(5) water molecule

is bonded slightly less strongly to Ca but more strongly to

K than are 0(3) and 0(4) , and appears to form slightly
- 10 -

stronger hydrogen bonds to the As04 group. As would be

expected to minimize repulsions, the cations and hydrogens are

arranged in approximately tetrahedral directions about each

water oxygen.

Discussion

o The average As-0 distance in CaKAs04 *8H2 0 is 1.685 A,

corrected for thermal motion, and the individual As-0

distances are equal within experimental error. Essentially

equal As-0 distances are expected from the close similarity

of the environments of the oxygen atoms of the As-0 group.

Inclusion of anomalous scattering effects, therefore, seemingly resulted in a refinement of the As-0 bond lengths

from unreasonable to reasonable values.

Other recently determined crystal structures which

contain As04 groups are CaHAs04 *2H2 O

1

1

(the mineral pharmacolite ) and 2H3 As04 ’HgO1

2

. In the refinement of the crystal

structure of CaHAs04 *2H2 0, corrections for anomalous scattering were made but no corrections for extinction or

absorption were included. Further, the As-0 bond lengths in

CaHAs04 *2H2 0 are perturbed by the cationic environment and

by the presence of a covalently bonded hydrogen atom.
- 11-

Nevertheless, three of the As-0 distances average to

o 1.672 A, close to those observed here. The fourth As-0

distance involves the oxygen with the covalently bonded

o hydrogen atom and is 1.729(9) A. in the determination of

the crystal structure of 2H3 As04 *H2 0, the data were collected

photographically using unfiltered Cu(Ka) radiation and were

corrected for absorption. Only isotropic refinement was

carried out, and no correction was made for anomalous

scattering. The As-0 distances in this relatively imprecise

4

- o o structural determination range from 1.594 A to 1.695 A and

o average to 1.652 A. The environment of the As04 group in

2H3 As04 *H2 0 is similar to that in CaKAs04 *8H2 0 and more

nearly equal As-0 distances would be expected than those

given for 2H3 As04 »H 2 0

It is interesting to note that no ion pairs between Ca

and As04 are formed in the CaKAs04 *8H2 0 structure, although

[CaC03 ]° ion pairs were found in the structure of CaC03 ^f^O1

and both the CaKAs04 *8H2 0 structure and the CaC03 *6H2 0

structure contain large amounts of water. Reasonable evidence

for the presence of [CaHP04 ]° and [CaH2 P04 ] + ion pairs in

calcium phosphate solutions has been given13

. The formation

of higher complexes 14 than pairs in these solutions may be

unlikely

.
- 12 -

The complete hydration of the Ca ion in the crystal

structure of CaKAs04 *8H2 0 is the only solid-state example

known to us with certainty. The complete hydration of the

K ion is surprising and is likewise the only solid-state

example known to us with certainty. Because no cationanion bonds are formed in CaKAs04

* 8H2 0, the low thermal

stability of the related series of compounds given in

Table 7 is undoubtedly a consequence of the importance of

hydrogen bonding in the structures. In this connection,

arsenates are known to form more stable hydrates than phosphates, and some calcium arsenate hydrates (see, for example,

references 15 and 16) have no stable counterpart among the

calcium phosphates. Thus a study of hydrated calcium arsenates should provide details of possible precursors of

crystallization in calcium arsenate and calcium phosphate

systems

.

The structure of CaKAs04 *8H2 0 (Figure 1) resembles that

of MgNH4 P04

• 6H2 0, struvite 1

' (Figure 2), though the two structures are not isomorphous. The MgNH4 P04

* 6H2 0 structure has
-13-

space-group Pmn2i ; the space-group of CaKAs04 *8H2 0 is Cm2m.

The structures of both compounds contain layers of X04 ions

and water molecules. The layers are parallel to (001) with

z, 0 in MgNI^ P04

* 6H2 0, and parallel to (010) with _y ~ 0 in

CaKAs04

* 8H2 0. Hydrated cations lie between these layers.

In MgNH4 P04

• 6^0, Mg is coordinated to six water oxygens

arranged in an approximate octahedron. The Ca ion in CaKAs04

•

8H2 0 lies near the site of Mg in MgNH4 P04

* 6H2 0, but is coordinated to the oxygens of eight water molecules. This

difference in cation coordinations is reflected in the

different numbers of waters of crystallization in the formulas of the two compounds.

In MgNH4 P04

• 6H2 O, the P04 group is positioned so that

the NUi ion hydrogen bonds to 0(1) of the P04 group

17 ’ 1 ® In

CaKAs04

• 8H2 0, the As04 group is in a special position at the

intersection of two mirror planes and cannot have the orientation P04 has in MgNH4 P04

• 6H2 0. Its orientation is such

that the oxygen atoms are not near the K ion, which occupies

a site in CaKAs04 ’8H2 0 near that of NH4

+ in MgNH4 P04

• 6H2 0.

The polyhedron of eight water oxygens which surround K

satisfactorily in CaKAs04 -8H2 0 may not be big enough for NH4
-14-

in MgNH 4 P0 4

• 6H 2 0 . The hydrogen bonds from NH4 to its environment are apparently too weak to increase the size of the

coordination polyhedron by inducing more water molecules to

crystallize in MgNH4 P0 4 -6H 2 0. Unlike the As04 group in

CaKAs0 4

• 8H2 0j the P04 group in MgNH4 P0 4

* 6H 2 0 forms bonds

with cations.

MgNH4 P04

* 6H2 0 exists as the biomineral struvite and has

been found in excreta19 * 20 from various forms of life, in

human urinary calculi 21

, in human lungs 22, and in canned

goods such as lobster23 and salmon17 . After removal from the

environment in which it formed, struvite changes 19 into

MgHP04 *3H2 0, newberyite. 24

CaNH4 P04

• 8H2 0, the calcium analogue of struvite, is very

unstable and decomposes to Ca5 (P04 )<pH, the major inorganic

phase in the body, within minutes at room temperature, even in

an aqueous environment. (As was remarked in the introduction,

CaKAs04 °8H2 0 was studied here because it was one of the most

stable members of the series.) Because of its unstability,

CaNH4 P04

* 8H2 0 probably does not exist as a biomineral, since

it would then have to be stable at 37°C. It is conceivable,

however, that it exists transiently even at 37°C as a highly
-15-

hydrated nucleus important in the early stages of crystallization of biominerals. The high hydration of the ions in

CaNH4 P04

• 8H2 0 and its fairly high rate of growth (of the

order of 1 mm/h) during its preparation near 0°C suggest that

it is easily produced in an aqueous environment under favorable conditions.
- 16-

The structural relationship of CaKAs04 *8H2 0 to

MgNH4 P04

* 6H2 0 speaks for the stability of this overall

structural type, which may be called the struvite-type

structure, after MgNH4 P04

• 6H2 0. The compounds given in

Tables 7 and 8 are some other probable members of this structural type. '"Structural type" is used here in the sense that

the structures show overall similarities, not in the sense

that they are isomorphous or nearly so.

Four structural types have emerged in calcium phosphates

and related compounds. These four types are:

(i) M5 (X04 ) 3 Y, the apatite type, of which there are

many examples (over 70 are listed in Wyckoff 25

);

(ii) MX04 -sheet containing compounds: CaS04

• 2H2 0

2

6

, CaHP04

‘ 2

H

2 0

2 7 ' 28 ’ 29

, Ca(H2 P04 ) 2 •

H

2 0

3

0

’ 3

1

’ 3

2

, CaHP04

3 3 * 3

1

* 3 4

, and probably Ca2 ( NH2 )

H

7 ( P04 ) 4

* 2H2 0

3

, Ca2 KH7 ( P04 ) 4

* 2

H

2 0

3 and CaClH2 P04 *

H

s 0

3 contain

corrugated CaP04 sheets; Ca2 P04 Cl 35 and probably

CaIH2 P04

• 4H2 O

3 contain planar sheets;

(iii) (M, N, ) 4 (X04 ) s or glaserite-type after K3 Na(S04 ) 2

(glaserite) : Ca5 (P04 ) 2 Si04

36 and Ca 7 Mg9 (Ca, Mg) 2 (P04 ) 1 both have structures related to the glaserite structure
-17abut with systematic cation vacancies, denoted

in the general formula above; cc-Ca 3 (P0 4 ) 2

37 ' 38

CaNaP0 4

39

, Ca 4Na 2 (P0 4 ) 4

39

, and the high temperature solid solution between a-Ca 2 Si04 and

a-Ca 3 (P0 4 ) 2

40,41 may be other examples of glaseritetype structures with systematic cation vacancies;

CaK 3 (P0 4 ) 2

42 is probably a monoclinic distortion

of the K 3Na(S04 ) 2 structure.

(iv) N^XO 4• nH 2 0 or struvite-type after MgNH4 P0 4

' 6H 2 0

(struvite) where n is 6 to 8 and N is a larger

cation than M. Several compounds which probably

have struvite-type structures are given in Tables

7 and 8

.

Acknowledgement. —Contributions to the data in Tables 7 and

8 were made by E. H. Brown, J. R. Lehr, J. P. Smith and

A. W. Frazier. B. M. Wallace grew rhe crystals used in this

study. We thank 0. S. Bowen and P. B. Kingsbury for technical

help. C. K. Johnson's ORTEP program was used in drawing

the figures. We, also, thank A. Whi taker and J. W. Jeffrey

for copies of references 17 and 18 prior to their publication.

part by research grant DE00572 to the American Dental

Association from the National Institute of Dental Research

and is part of the dental research program conducted by

the National Bureau of Standards, in cooperation with the

American Dental Association? the United States Army Medical

Research and Development Command; the Dental Sciences Division of the School of Aerospace Medicine, USAF? the National

Institute of Dental Research; and the Veterans Administration.
References

1. B. Dickens and w. E. Brown, Inorq. Chem .

,

1, 480 (1970)

.

2. B. Dickens and J. S. Bowen, J. Res. Nat. Bureau Stands .

,

in press (1971)

.

3. E. H. Brown, W. E. Brown, J. R. Lehr, J. P. Smith and

A. W. Frazier, private communication.

4. C. Dickinson, J. M. Stewart and J. R. Holden, Acta Cryst .

,

2JL, 663 (1966).

5. "International Tables for X-ray Crystallography", Vol.II,

The Kynoch Press, Birmingham, England, 1962, p. 202.

6. R. McWeeny, Acta Cryst . , 4, 513 (1951).

7. J. M. Stewart, Editor, Technical Report 67-58, University

of Maryland, College Park, Maryland 20742 (December 1967)

.

8. D. T. Cromer and J. B. Mann, Acta Cryst .

,

A24, 104 (1968)

f

• D. T. Cromer, Acta Cryst., 18, 17 (1965)

.

10. W. R. Busing and H. A. Levy, Acta Cryst .

,

17, 142 (1964)

.

11. G. Ferraris, Acta Cryst . , B2

5

, 1544 (1969)

.

12. H. Worzala, Acta Cryst ., B24-, 987 (1968).

13. T. M. Gregory, E. C. Moreno and W. E. Brown, J. Res. Nat . Bureau Stands ., 74&, 461 (1970).

14. C. W. Childs, Inorg . Chem. , 9, 2465 (1970)

15. R. Pierrot, Bull. Soc. Franc. Miner. Crist ., 8J7, 169 (1964).

18
-19-

16. B. Dickens, "Structural Properties of Hydroxyapatite

and Related Compounds" (Ed. W. E. Brown and R. A. Young)

Gordon & Breach, New York, in preparation (1972)

.

17. A. Whitaker and J. W. Jeffrey, Acta Cryst . , B26 , 1429 (1970).

18. A. Whitaker and Ja W. Jeffrey, ibid . , B26 , 1440 (1970).

19. A. Whitaker, Min. Mag. , 36 , 820 (1968)

.

20. L. H. Cohen and P. H. Ribbe, Amer. Min. . 51 , 1755 (1966)

.

21. K. Lonsdale and D. J. Sutor, Science , 154 , 1353 (1966).

22. M. W. Porter, Amer. Min ., 9, 93 (1924).

23. V. L. Ayres, Amer, Min . , 27 , 387 (1942).

24. D. J. Sutor, Acta Cryst ., 23 , 418 (1967).

25. R. W. G. Wyckoff, "Crystal Structures", second edition,

Interscience, John Wiley and Sons, New York (1965), p. 242.

26. M. Atoji and R. E. Rundle, J. Chem. Phys ., 29^, 1306 (1958).

27. C. A. Beevers, Acta Cryst . , 11 , 273 (1958).

28. D. W. Jones and J. A. S. Smith, J. Chem. Soc ., 1414 (1962).

29. N. A. Curry and D. W. Jones, private communication.

30. G. MacLennan and C. A. Beevers, Acta Cryst ., 9_, 187 (1956).

31. D. W. Jones and D. W. J. Cruickshank, Z. Krist ., 116

,

101 (1961).
- 20-

32. B. Dickens and J. S. Bowen, Acta Cryst . , in press (1971)

33. G. MacLennan and C. A. Beevers, Acta Cryst . , 8, 579 (1955)

34. B. Dickens and J. S. Bowen, submitted to Acta Cryst .

35. M. Greenblatt, E. Banks and B. Post, Acta Cryst . , 23 , 166 (1967); Acta Cryst ., B25, 2170 (1969).

36. B. Dickens and W. E. Brown, TMPM, in press.

37. B. Dickens and W. E. Brown, TMPM, in press.

38. J. Ando, Bull. Chem, Soc. Japan , 3J^, 201 (1958) .

39. J. Ando and S. Matsuno, Bull. Chem. Soc. Japan, 41, 342

(1968)

.

40. J. Berak and J. Wo jciechowska, Roczniki Chemii ., 30,

757 (1956).

41. R. W. Nurse, J. H. Welch and W. Gutt, J. Chem, Soc ., 1077 (1959).

42. W. E. Brown and B. O. Fowler, Internat. Assoc. Dent. Res.,

Program and Abstracts of Papers , 1967 (Abstract)

.
able

1.

Atomic

Parameters

of

CaKAs

04*8H20

CO

co rH CM '—

0} 1 i ! ^ 1 ^ i ml 1 1 1 ^ 1 rH i o 9 6 6 T i 1

Eh

CO • •H i 1 1 | 1 | 1 03 - -P +

mi i l 1 1 1 1 1 o T5 C • 0 0 0) 4H g 0 0

°*i

CO 3 G CO f D1 -H ml =H| ip

CQ x\

c* rH CN rH 0 0 Jc CO i \ 1 I — 1 s—1 1— U P ^1 03 ml j 1 1 1 in 1 O rH 3 PQ • • • tJ3 03 + 9t iH o -H 0 p 1 MH P *K

10 P zs X\

CQ G & 03 +

03 03 ml o?|

in r- IN 0 1 rG

CO *>

— *>— »

rH rH rH rH rH •H P * co CO ro r- '— '

-— s— P 03 rQl ml o ro 00 CN r- CO r- •H 03 rH CN o P rH rH rH rH G 0

tJ3 i—1 + f •H 03 0

03 X

•H

CN p p +

in r- CN

—sX—s

03 P ml

03 cw '— *>

rH CN rH CN rH 03 03 rXl

c* o rv—1 '—

*•

— '

1 s— f—) g •}c X

ml CN 03 r- 03 CN ro 1 0j 03 • • • • • • t • G rH rH iH o rH iH CN ro rH •H rH 'vf m G \ *

03 P P0 P

iHiQ.

rQ

4«0

in CN P 0 x CN

rH '— *>

'—

rH rH rH rH rH P 0

ml

ID o 03 >

1—1 '

s—1 *

1 0 0

rH CO 03 CN 03 ID CN iH g

nD 0 p

rH rH o rH iH rH rH CN p >1

03 0 0p C r-H 0

03 0 ,G P G p in in 03 -HP 0k

Nj

r- in 0

r- ro CN P 0 r o 0 03 o CN CO 0 ,G

in in • 1 I • CN LO CN 03 P P • • o • o • • • 0 o o o o o o 03 G 0 -H B0

JZ p P rO 0

iH ID l> ro G 0 g

'w' 0 P 0 H O r- ro iH ro O' P G P

in t"* 03 1—Iro O 03 0 a 0

r- CO o r- CN O O iD a g Qa ro rH • o o O CN 0 • • o • • • t • G 0 rH o o o o o Q O •H 0 I 0 g

03 P P 0 0 0 P £ rG

LO LO G Eh '—

'

—•" tJ3 T3 00 03 •H &

XI

CN CN rH

h 0 4< o in o o o CN t—! t o • • ro in CN CN o o o o « 9 <9 0 o O O o

psj i!

g| g! gi gi r~ij g Bj U

4J 03 rH CN ro uo < u & < O O O O O

N|

>1+ + H|W

H|0l

XI

XI + + H[N

H|03

XI

NlI

x"| I

Nj

XI

NI

>1+

H|«

x“| i

H|C\3

N|

>1+

H|C12 • 0P

-H

03 P0*4-1 o

>1pP

CD

1/2

N| XI H i X| H|OJ

03 PG0g0i—I 0

!>i pP0

Fj * 03 *
Table 2 Observed and calculated structure

for CaKAsO^

factors

2 705 73<* •.1«70 145b

t> 755 70b

0 463 479

31 bOU

193 0

21 500

.. 332 331

1U 2b* 2b4

12 179 I7tt

u 1*5 117 50U

2 3b9 35b 500

* 107 107 500

3 532 560

i 363 363

Id 350 350

12 166 165

H.0.6

it 710 705

2 **8l 474

4 520 53b

n 373 385

i 2AB 29b

10 242 24

2

n 75 64 0

2 159 152 600

4 wb 16 500

h 31* 9 500

« 7b 71 500

10 38* 25 0

0 499 481

2 292 301

4 385 360

a 273 281

•t 193 198

10 198 18b

M* 0*9

? 25" 255

4 325 329

i, 232 241

9 179 179

37* 13 500

37* 21 0 J7« 2b 0

u 1HH 177 0

> 172 157 0

4 lf,3 151 0 M* 1*0

1 596 99

3 138 165 190

5 39b 398 b9

7 72 87 865

9 ibl 14b 71

II b2 59 952

| 939 970 b

3 7U1 791 3o

5 59b 6"6 98b

7 -33 ««33 23

l 265 266 0

11 240 244 999 H.1.2

1 482 S 1 4 897

\ 22‘* 213 245

-> 442 470 903

7 117 96 177

•# lo4 163 935

11 66 SblOOU

369 39* 980

M.l#4

1 191 191 27

3 45 53 766

5 22 4 234 33

7 40 38 851

9 U6 109

11 39* 44 961 H.l.5

1 598 603 1 3 500 501 55

5 421 449 966

7 333 343 45

9 208 218 983

11 200 197 6 M. 1.6

1 271 270 992

3 106 162 87

5 265 269 974

N.1.7

1 419 416 995

3 360 382 970

5 316 323 14

7 2b2 2 72 963

9 173 170 11 M# 1 # 8

1 88 95 971

3 59 16 113

5 101 116 964

7 32* 15 194

9 63 56 997

1 257 263 979

3 222 227 29

5 225 228 948

7 185 171 30

9 llfl 126 960 H.1.10

l 137 134 43

3 111 80 68

5 143 12Q 43

7 39* 50 64

1 260 236 994

3 228 216 9«1

5 201 191 3

H.2.0

0 878 776 943

2 962 916 69

4 459 458 987

6 351 350 994

b 257 255 33

10 161 159 944

1? 109 113 14 H.g.l

0 096 861 980

2 910 920 5?

4 568 555 26

6 496 491 16

4 281 290 50

10 235 2 42 11 12 158 147 44 H,2.2

0 946 917 934

2 595 583 45

4 356 361 937

6 155 168 832

0 65 71 927

10 140 146 911

12 33* 31 837 H.2.3

0 255 276 862

2 651 662 22

4 252 262 977

6 362 372 991

8 218 224 37

10 159 162 980

12 136 132 33

0 461 460 92u

2 3«4 387 28

<* 356 3 7 P 967

6 228 243 985

H 101 1B1 in 10 123 140 925

12 86 86 98.9 H.2.5

II 761 769 26

2 526 532 5°

4 504 515 37

6 398 409 30

8 246 251 61

10 241 228 26 H.2.6

0 407 404 954

2 89 69 19

4 252 24b 972

6 135 142 939

8 81 94 993

10 112 119 934 H.2.7

0 111 129 921

2 389 376 34

4 132 134 4 6 206 214 Q

8 162 147 SO

10 103 97 0 H.2.8

0 251 276 916

2 102 114 900

4 192 199 924

6 129 134 889

8 85 92 940

10 117 102 897

H# ? » 9

0 341 330 24

2 247 241 46

4 266 264 34

6 215 213 28

8 162 141 60 H.2. 10

0 201 180 955

2 142 132 5

4 156 143 970

6 122 114 960

8 86 87 995 H.2.U

0 104 99 51

2 211 191 68

4 123 106 71

6 135 124 53

0 154 140 917

2 35* 55 823

4 104 103 915

H.3.0

11128 969 61 31029 972 156

5 699 713 995

7 461 466 129

9 371 366 31

11 204 203 70 M.3.1

1 285 285 218

3 189 196 922

5 184 203 753

7 140 149 901

9 55 72 778

11 100 92 846 H.3.2

11136 1153 19

3 873 879 11 5 699 700 29

7 462 471 15

9 380 383 40

11 212 220 12 H»3»3

1 471 500 802

3 193 203 897

5 347 375 784

7 124 141 919

9 131 143 794

11 86 100 846

1 666 667 32

3 614 632 108

5 507 535 999

7 345 354 99 9 2Q2 311 27

11 180 174 52 H.3.S

l 40 56 793

3 133 137 895

5 27* 36 172

7 120 124 883

9 30* 17 197

11 63 70 847

1 594 591 44

3 517 S23 57

5 455 462 33

7 316 322 56

9 285 280 46

11 156 164 39

M» 3» 7

1 231 247 042

3 151 136 936

5 229 250 813

7 90 88 944

9 109 112 814

1 372 366 17

3 335 325 44

5 298 308 6

7 224 ?15 46

9 200 197 26 H.3.9

1 52 75 794

3 ton 102 851

5 48 44 223

7 95 87 847

9 34* 23 760 M.3.10

1 292 282 53

3 284 262 87

5 245 234 32

7 189 182 90

94 880

68 983

95 847

01161 1013 990

2 143 115 124

4 500 455 5

6 155 162 903

8 157 154 993

IP 127 125 921

l? 36* 35 950

H* 4 » 1

n 443 431 35 21179 1133 59

4 508 509 56

6 493 481 39

n 378 373 5o

10 219 217 31 12 191 190 4b

0 726 709 214

? 265 265 951

4 307 343 796

6 180 197 808

8 147 145 941

0 119 129 773

1? 1* 59 949

486 4°8 13

517 942

117 d85

350 962

161 884

133 967 me 901

40 941

n 304

2 798

4 356

6 382

8 319

10 1 67

103 831 105 984

136 901

83 831

83 992

65 811

0 388

2 322

4 297

6 240

8 213

10 1 68

221 b 77

134 915

165 899

110 065

89 941

0 203 209 1 2 429 413 42

4 227 229 23

6 248 242 25

e 209 2C4 39

0 104 Q9 971

2 36* 30 46

4 83 81 989

6 37* 30 927

0 169 172 3b

? 168 166 37

4 155 153 37

6 137 133 28

1 114 119 169

3 302 2«i 953

5 114 03 107

7 214 206 960

9 133 127 20

11 63 69 924

M.S. 1

1 371 362 41

3 60S 576 50

6 200 2O0 10 7 3311 324 43

9 147 146 33

11 132 128 39

H» 6* 2

1 743 728 939

3 638 524 18

5 528 555 919

7 247 247 22

9 286 287 944

11 124 114 957

1 626 526 b

3 662 666 994

5 234 261 38

7 370 332 99o

9 163 16u 35

11 135 147 6

1 237 239 968

3 307 314 971

5 153 157 984

7 189 194 959

9 138 147 964

11 71 79 930

H» 5* 5

1 202 215 68

3 297 302 109

5 120 131 997

7 210 213 102

9 104 95 34

11 88 87 63

1 300 297 964

3 289 286 9 5 255 259 939

7 161 162 5 9 185 170 960

11 58 80 955 h.5»7

1 296 290 21

3 378 3Q4 993

5 160 167 59

7 240 255 992

9 122 112 57

M» 5* 8

1 251 256 948

3 237 240 968

5 202 207 933

7 142 156 969

9 152 147 949

H» 5 »

9

1 131 127 46

3 16b 161 97

5 92 85 999

7 127 118 103

1 135 131 976

3 143 141 983

5 10b 103 971

7 105 100 974

1 124 113 67

3 157 146 32

5 98 75 112

H'6’0

0 47b 450 71 21077 950 101

4 526 484 71

b 423 400 101

8 397 395 80

10 164 161 84

12 203 193 97

H»6» 1

0 360 336 755

2 611 557 891

4 310 293 837

6 258 250 872

8 217 232 873

10 lib lib 847

12 122 119 878

H» 6 »

2

0 941 085 84

2 410 397 70

4 664 634 75

6 342 330 03

0 319 319 68

10 235 208 85

12 131 139 86

rt*6* 3

0 389 387 220

2 60b 615 934

4 293 315 816

6 264 277 888

8 229 232 889

10 10b 123 829

12 127 124 904

0 441. 440 71

2 657 674 85

4 442 454 64

6 339 337 85

8 329 336 77

10 173 157 79

rt» 6* 5

0 208 204 911

2 333 336 860

4 218 218 000

6 171 184 876

0 17b 175 867

10 80 92 878

rt. 6»6

0 391 309 85

2 309 311 95

4 328 345 85

6 223 220 104

8 210 220 81

10 137 134 96

H» 6* 7

0 219 247 752

2 329 329 937

<4 173 197 810

6 160 173 860

8 150 159 089

10 93 90 818

1 * 6*8

0 343 338 64

2 327 321 67 8 i 6 9 181 958

4 309 302 62 10 88 99 47

6 221 214 75

8 212 211 67 rl* 8* 2 .6*9 303

w 428

160 929 ,* 312

212 884 6 239

157 910 8 217

136 898 10 99

8 129 123 889

160 103

201 104 159 95

130 112

0 363

2 363

4 267

6 235

4 158

10 124

294 907

433 42 296 987

232 28

230 10 113 995

380 108 359 967

261 43 231 3b

162 973

lie 61

91 801 2 311

4 377

12 b 223

0 213

163 73 10 146

479 404 39

784

763 835

789

053 10 782

2 360

4 134

6 183

303 94

U

379 lb 221 997 209 97b

10b 899

371 99o

140 930

10b 8 139 9b7

1 509

3 632

5 334

7 366

9 197

11 172

1 509

3 611

5 248

7 341

9 184

11 119

500 114 574 47 335 141 362 49

193 106 176 82 *7*2509 931 626 913

252 945

350 908

185 922

118 893 H.7,3

1 627 636 71

3 607 b 1 3 64

5 396 408 79

7 380 307 69

9 234 229 65

11 187 192 82

1 283 295 849

3 222 214 066

5 250 263 664

7 133 118 852

9 164 169 872

11 30* 61 829

*7*5292 131 351 30 233 190 262 33 133 140 129 76

1 280

3 350

5 224

7 254

9 128

11 123

1 244

3 286

5 164

7 177

2 52 880

290 880

170 885

181 880

9 124 127 889 u

H.7.7

1 390 394 59

3 373 376 64

5 284 292 53

7 260 263 71 9 181 177 49

62

238 984

243 906

219 963

160 99b

164 983

96 987

219 98

183 94b

152 5b

130 3b

94 958

U 280 265 2b

2 231 237 3

4 247 232 14

b 168 173 20

0 164 lbO 999

0 37* 69 97U

2 21 2 197 lb

<4 108 85 979

b 116 109 2b

0 169 169 9

2 134 131 94b

4 150 147 990

6 101 103 900

1 294 274 142

3 252 245 25

5 283 242 177

7 177 179 43

132 139

1 185 192 Q13

3 187 198 908

5 143 146 °1

0

7 140 125 903

9 130 105 909 H.7.9

1 206 191 106

3 243 226 40

5 149 150 160

7 175 174 34

109 044

97 84b

95 844

1 177 172 54

3 180 170 55

5 149 136 52 M.7.12

1 89 94 910 H*6*0

0 727 644 43

2 443 379 872

4 493 441 12 6 269 241 984

8 239 229 956

10 167 150 15 M.0. 1

0 163 160 30

2 534 496 981

4 221 206 993

6 259 250 17

1 394

3 493

5 251

7 330

1 259

3 221

5 245

1 322

3 294

5 266

7 201

1 256

3 195

6 235

7 124

H.9.7

1 261 275 958

3 345 352 927

5 148 164 982

7 263 263 929

9 110 108 947 H.9.8

1 201 214 126

3 166 172 122

5 182 183 120

7 114 120 130

1 185 179 908

3 139 152 8R7

6 156 155 920

7 105 115 900

1 105 102 96

3 103 06 55

5 86 93 118

M. 10.0

0 716 657 090

2 528 4Q1 921

4 543 485 894

6 300 356 911

8 278 269 908

10 216 204 091

H. 10.

1

0 415 420 137

2 312 312 64

4 300 296 128

6 291 276 103

8 133 139 91 10 ISO l 7 l 133

H. 10.2

0 459 450 3

2 355 351 033

4 344 337 960

6 242 230 911

8 189 196 888

10 147 949

.10*3

93 119

1 455 439 90b

3 498 464 88b

b 341 29b 921

7 312 309 09b

Q 170 17b 093

11 146 156 930 H»9.2

1 b23 541 95

3 356 370 127

5 471 442 75

7 214 232 148

t 231 222 75

11 124 135 141 .9*3

400 955

496 921 229 9b4

342 924

142 932

163 950

240 160 157 78

131 132

91 132

335 805

298 859

2b8 897

204 877

162 877

272 85

20 2 80 237 80 133 109

133 7b

0 296 301 174

2 354 37R 12R

4 249 230 160

6 259 274 134

R 146 145 13Q

10 147 150 150

0 44R 462 908

? 341 357 923

4 346 363 907

6 264 277 914

0 193 212 911

10 150 163 904 H.10.5

0 356 3P0 119

2 220 218 10

4 254 251 104

5 210 216 81 0 123 114 54

10 143 150 117

H* 10.6

0 307 322 940

2 275 280 B62

4 266 264 923

6 192 205 B90

R lbO 168 0R5

0 136 161 156

2 260 257 131

4 144 149 154

6 182 1R5 133

H 101 109 136

H. 10.

B

0 232 232 953

2 174 180 904

4 195 189 939

6 130 147 925

H 105 119 917 H.10.9

0 234 225 127

2 133 133 45

4 169 162 115

6 138 140 93

0 189 185 096

2 164 161 0R7

4 165 159 891

H. 11.0

1 390 339 998

3 132 123 1 5 408 357 9R9

7 76 81 48

9 190 1 85 998

11 86 BA 25 H.11.1

1 310 307 974

3 203 287 942

5 250 220 994

7 212 209 940

9 9fl 100 976

11 117 123 967

H.11.2

1 323 325 52

3 297 303 31

5 274 249 71

7 199 204 22

9 140 147 63 H.11.3

1 269 283 999

3 179 182 979

5 253 240 fl 7 133 132 970

9 113 109 990 H.U.4

1 24R 261 14

3 115 127 46

5 273 273 11

7 73 84 56

9 160 150 16

M. 1 1.5

1 210 212 949

3 223 256 920

5 127 125 976

7 196 195 924

H.ll .6

l 263 256 21

3 205 214 16

5 246 217 27

7 159 148 14 9 122 133 2fl H.ll. 7

1 107 196 995

3 104 114 902

5 103 106 996

7 67 02 973

1 163 163 59

3 llfl 123 62

5 159 158 55

1 R6 88 936

3 119 118 913

5 44* 48 970

H* 12.0

0 459 435 77

2 161 154 982

4 321 301 71 6 165 167 44

8 116 113 64

10 121 120 64

H. 12.

1

0 441 432 94R

2 399 404 960

4 374 335 Q52

6 336 320 962

8 212 199 943

10 105 184 972

H. 12*2

0 138 130 22

2 105 211 227

4 99 110 109

6 R6 99 145

0 R2 100 1Q9

10 77 52 57

0 322 318 1 2 273 297 920

4 251 243 075

6 252 243 960

8 130 151 933

10 146 150 992

0 293 293 41

2 98 100 34

4 204 200 82

6 115 117 54

8 71 84 89 H.12.5

0 377 382 932

2 347 363 9R1

4 293 307 939

6 277 297 966

8 170 105 956

H. 12.6

0 154 160 34

2 95 110 152

4 122 122 73

6 04 85 00

8 59 71 132 H.12.7

0 213 210 17

2 104 197 917

4 161 170 995

6 160 166 967

8 116 109 940 H.12.8

0 103 105 8^

2 39* 62 176

4 85 81 136

6 39* 55 110

0 221 215 035

2 205 205 987

4 177 177 91*7

1 120 124 997

M.13.0

1 445 410 945

3 402 402 957

5 343 312 936

7 282 274 952

9 201 192 950

H. 13.

1

1 173 1R1 121

3 137 149 163

5 149 152 113

7 105 Ob 140

9 82 88 159 M.l.W

1 415 423 950

3 246 265 949

5 439 41 1 950

7 ISO 160 941

9 234 232 955 H.13.3

1 109 13b 162

3 114 140 139

0 7R 108 192

7 93 101 lib

9 67 74 220

H* 13.4

1 33.3 331 93/

3 283 303 954

5 279 26fl 933

7 206 212 946

Q 100 167 94b H.13.5

1 166 155 103

3 109 108 181

5 160 162 79

7 79 72 182

304 319 955

2 42 236 950

30A 2°2 952

147 160 951

H. 15*0

1 138 136 39

3 68 72 157

5 168 153 999

7 37* 41 231

9 102 97 13 H.15.1

1 274 282 995

3 208 283 9

5 220 212 989

7 204 204 6

9 142 13b 7

1 223 217 969

3 268 251 9IJ2 5 170 151 955

7 199 186 903

1 154 167 H.15.2

1 107 99 958

3 133 144 27 5111 b9 886

5 142 149

25 1 6R 75 S3

1 263 270 978

3 212 22 5 9RR

5 243 237 978

7 14b 157 9R0

91 100 990

53 53 97

114 115 974

34* 24 139

1 193 218 11

3 234 255 20

5 154 147 5

7 174 192 17

0 125 164 <*8 2 195 199 20

4 142 14b 36 6 124 137 39

0 76 76 999

2 151 146 907

4 96 91 963

6 85 77 915

10 0 150

117 119

RO 203

90 94

1 °6 93b

154 943

102 933

1 175 100 949

H. 14.0

0 323 2°3 9bB

2 272 273 111

4 266 235 lb

6 172 1 7 3 41

0 162 157 92 H.14* 1

0 2° 1 2^5 973

? 2R \ 200 975

9 230 233 97b

6 225 216 967

9 140 142 970

H * 1 4 * ?

0 251 238 903

2 105 1Q9 991

4 1R4 IPS 92U

6 163 166 948

9 110 105 954

0 229 231 975

2 184 190 104

4 194 102 17

6 109 1 30 31

0 131 123 66

0 256 256 9

2 260 26b 9b

5

4 216 213 997

6 210 1°3 970

« 136 134 960

163 57

115 7b 143 fa9 94 54

0 167 163 874 2111 121 b

4 142 122 90U

6 129 108 942

185 196 991 146 150 999

18b 182 990

0 140 166 990

1 1 30 132 2 H * 16.0

0 341 343 29

2 33b 336 985

4 325 314 1-8 b 232 232 993

b 244 217 9

0 113 129 925

0 115 135 106

2 172 166 13

4 122 123 74

1 200

3 157

5 172

H. 16*2

0 312 329 92b

2 252 254 18

4 272 272 954

b 183 195 968

0 17b 17b 2

' 1 b * 3

1 210 224 20

3 250 266 27

5 166 160 9 lb 230

59 931

15 84 24 955

0 287 290 4 2 280 287 983

4 250 264 1 b 194 202 903

H. 19.5

1 42* 28 771

0 35* 34 134

2 108 95 894

4 49 36 7 227 970

198 18 201 987

30 799

43 871

14 205 0

. 20.2

2 97 926

2 184 190

3 132 13158 105

87 0 6 142

98 10O

216 992 215 992

167 980 1 15b 990 Columns are h, 10F Q

, 10F C and phase in millicycles. "Unobserved"

reflections are marked by *. F^ does not include corrections for

extinction or anomalous dispersion. F and F are on an absolute

scale. 0 c
Table

3.

Probable

positions

of

the

hydrogen

atoms

in

CaKAsO

co CO r- in cr> r- CO

N | rH CO rH CN

T5 • • • • CD -P0 X

CO in ID r- rH CM CN rH o a O o CO CN u • • • • rH 1 f0u

XI

CN in CO

CT> in CO CO

CO rH CN rH c • • • • •H

to -PrQ0 • o 0 -P r^ r» CO rH -P X >—

"* '

0 o ID CN 0^ T5 •P

N | uo rH 0> CO 0

rH rH CN to 0 • • • • 3 ,CP 0

02 to P n3

CD -P ID 10 in 10 0 a P C *—’ "

1 *

'

5 to

(Q 0 rH c^ o 10 3 £ O o CN 'sj* to to W CD o o CO CN C 0

to c t • • • 0 rH

•rH 1 •rH rQ

4-> MH -P to

02 CD «*-v ,—<•rl -p

(0 P r- <T\ to CD XI

*»•< '— >

1 *— 0 0 P in <r> ID O a, A

CO CO in -P CO rH CN rH a • • • • 0 c

Cn •H 0p

T5 0

>H c

N|

CO rH in £ 0

CD rH CN CN •H U to • • • • 'O -p a -h 0 c

CD to -p 0 P CD >1

CN o 1—1

rH 0 £ 0 rC O o CO CN rH

MH 4-> • • 1 • 3 to MH C 1 O 0

*h ip i—1 0 Q 02 0 C

XI

in

U 0

CO rH CN i—i

-p • • • • 0 to •H

Fh

rH CN CO

S3 S3 SJ
-24-

Table 4. The cation environments in CaKAs04 *8H2 0

o atoms Distance, A

Ca, 0(4^, 4-r-r

) 2.459(5)

Ca , 0(3?, ) 2.469(6)

Ca, 0(5I

, 5°-'. 5TM , 5°) 2.490(3)

K, 0(5r, 5^, 5r, 5s ) 2.746(3)

K, 0I3111 , 3°-) 2.918(6)

K, 0(4?ij

, 4

1)L

) 2.960(7)

In all tables of interatomic distances and angles,

the figures in parentheses are standard deviations

in the last digit and were calculated from the

standard deviation in the atomic positional parameters. They include terms from the variancecovariance matrix.
-25-

Table 5. The As04 group and its environment in

atoms

CaKAs04 *8H

2

0

o distance, A or anqle, deq. ridinq

^

lower (a)

As, 0(1, 1) 1.682(4) 1.684 1.690 A

As, 0(2, 2) 1.684(4) 1.685 1.692

0(1), As, 0(1) 113.1(3) 0

0(1), As, 0(2) 107.5(1)

0(2), As, 0(2) 113.7(3)

0(1), 0(1) 2.807(7) A

0(1), 0(2) 2.715(5)

0(2), 0(2) 2.820(7)

0(1) , H(2X, 2E?) 1.87

0(1) , H(4X 4tt) 1.81

0(1), Op^S^) 2.759(4)

0(1), 0(4x?4'lr

) 2.830(4)*

0(2) , H (11, 1)** 1.89

0(2), H(3I, 3) 1.81

0(2), 0(5HI) 2.755(4)

0(2), OpIH) 2.848(4)*

(a) lower bound and riding model corrections for thermal motion

* hydrogen bond between these two oxygens,.

These hydrogen bonds may be seen in Figure 1 if the

environments of 0(2) and 0(2X

) in the right hand side of the

As0 4 ion in the center of the figure are combined. 0(2)

and 0(2I

) are related by the _c translation.
- 26 - Table 6. The environments of the water

molecules in CaKAsO -8H 0 4 2

water

molecule

H(l) ,0(3) ,H(1)

H (2 ) , 0(4), H(2)

H (3) , 0(5), H (4)

atoms

OP337

) .Ca327

0 ( 3-111 ) , K1

0(3 J3: ),0(2I, 2)

H ( 1) , 0 (2 X ) 0(3), H(l) , 0(2)

0(2), 0(3), 0(2)

0 (4^ ) , Ca72

0 (4-=tsr ) , K3

0 (4XE ) , 0(1,1)

H (2 ) , 0(1)

0(4), H (2 ) , 0(1)

0(1), 0(4), 0(1)

0(5X

), Ca^

Op3

), K 3_

015 1 ), O ( 2 X) 0(53

), 0(1)

H (3) , 0(2*)

H (4

1

) , 0(1)

0(5), H (3) , 0(2)

0(5), H (4) , 0(1)

0(1), 0(5), 0(2)

Distance, or

deg.

2.469(6)

2.918(6)

2.848(4)*

1.89

175.7°

98.8 (2)

2.459 (5)

2.960 (7)

2.830 (4)*

1.87

175.6 ° 98.7 (2)

2.490 (3)

2.746 (3)

2.755(4)*

2.759(4)*

1.81

1.81

168.7°

168.7

119.4 (1)

angle

©

A.

* hydrogen bond between these two oxygens.
-27-

Tab 1e 7 . Some members of the struvite series

MgNEi P04 MgNH* As O4 CaNH* P04 CaNHt As04 MgKP04 MgKAs 04 CaKAs 04

• 6H2 0 • 7Ha 0 •7HaO • 6H0O • 6Hg 0 •9HeO

0 Init-cell dimensions, A

a 6.09 6.14 6.30 6.38 6.21 6.23 7.146(1)

b 11.18 11.14 11.96 12.07 11.10 11.26 11.696(2)

c 6.97 7.00 7.18 7.27 6.91 7.03 7.100(2)

tngle beta 90° 90° 90.83° 91.47® 90° 90° 90°

formula weights per

unit cell 2 2 2 2 2 2 2

-3

Density, calculated, g*cm

X-ray 1.71 1.99 1.70 1.91 1.85 2.08 1.933

Optical 1.72 1.95 1.71 1.86 1.91 2.15 2.10

Crystal system Orthorh. Orthorh. Monoc 1

.

Monoc 1. Orthorh. Orthorh . Orthorh.

Dlass (mm) (mm) ( 2 ) (2) (mm) (mm) (mm)

lefractive N—

1.496 1.518* 1.495 1.514 1.477 1.503 1.497

indices: 1.497s 1.519 1.497s 1.516 1.481 1.509 1.516

i

122In 1.505 1.528 1.514 1.535 1.487 1.5094 1. 5195

)ptic sign (+) (+) (+) (+) (+) (-) (-)

)ptic angle 2V: measured 41° 25° 41.5° 34° - 22.5° 46-47°

calculated - - - - 77.5° - 46-47°

Dispersion r<v none none none r<v r>v r>v

weak weak moderate moderate

Dptio axial plane (010) (001) -(001) -(001) (001) (001) (100)

Extinction angle zAa - - 6° 6.5° - - - (in obtuse beta)

Orientation: N

~x

C b b b b b b

N

b c_ ^iL c. c_ a N~z a a cl f^Ei a a c
- 28-

Table 8. Other probable members of the struvite

series

Mg

2 KH(P04

) 2

*15H

2

0 MgKAsO^- 5H

2

0 MgHP0

4

«7H,

, , O unit cell dimensions, A

a. 6.30 10.79 11.35

b 12.29 10.79 25.36

_c 6.55 12.39 6. 60

angles

,

deg.

a 93.6° 90° 90°

3 89 0 7

° 90° 95°

Y 95.3° 120° 90°

formula weights

per unit cell

z 1 6 8

crystal

system tricl. hexagonal monocl.
03 3C 4J d

CO 40 d CD o O 42 T3 4-1 4-1 CD CD 4*1 T3

42 44 d CD u O cd d

B d

4-1 d a) O •H CO <4-1 60 •H CD • d •H d CO o 5-( B CD •H O CD CD <J

4-1 4-1 d d

CO CD CO co co d 4-4

4-1 H CO CO CO CO r-H *H 3 0) Cd T3

r-H • 4-1 d 1—

1

O cO CD U

•H 04 C 6 *h

P2 •H 3 g a 00 'T3 d o

•H • d 4-1 a <j- o d co o o O cd d a CO a B CD

co < O 4—1 o a & d

CD cd •H •H d u 4d 42

CD CL 4-1 M—

f

4-> 44 cd •H O

CO o d £

00 CO <3 CD o CO CD d I—1 £ r—• d I—1 O 40

• • 4-1 cd 4-4 Cd

i—i a 4-1 Cd 4-) d CO

(D d K’'! CD CD d 4-1 d 42 42 d CO o H 4-i 60

•H

P«H
3

cd3

•H o JZ

cni a

PC 3 *H 'G r£ o 3 • -p £

CN*H <f

PC o ,3 * vO O Pm 4-J /—n 3

•H

• CN S3- -H lo -"-v 'd’ffi PC ^ W LO O 00 2 O'-'

cn • oo « o

<t M-l O i—I o S cn p >,

txo <j o a) oo e S PP 4-1 p p 3

Cd <4-4 3 >

<4H U CO 14-1 4-1 -H o p QJ 3 00

<4-4 CU O B 3 O U 3 3

P QJ 33 P 3 • 3 p B 3 3 3 P cd cd 3 a 3 P a 4C p 4-1 3

3 4-J Cd P rH •H ,3 P a 3 3 3 3

P o p •rH 3

CO p a 3 p 4-4 •H P 3 3 3

r—

1

p B *H XI 33

cd cd o P >*

4-1 rH 4-1 3 r3

CO •h cd 3 > B 6 JC •H 3

P •H QJ o 4-1 4-1 P a co x: p •rH 3

Eh OH <4-1 3 rC 3 3 O O

rC O 3 3- X) H •H • 3 3 1 3

4-1 i—

1

O 3 P

cd 3 •H O 3

• • 4-> QJ •P 4-J 3 3

tN 3 P a 00

QJ d 3 3 3 •rH 0) •H 00 P a P 3

p P *H 3 X 3 3

3 O Pn S 3 3 33 00 •H