Synthesis, structure, and thermal expansion of sodium zirconium arsenate phosphates

Article abstract of DOI:10.1134/S0036023611090294

Sodium zirconium arsenate phosphates NaZr₂(AsO₄) _x (PO₄)_3-x were synthesized by precipitation technique and studied by X-ray diffraction and IR spectroscopy. In the series of NaZr₂(AsO₄) _x (PO₄)_3-x, continuous substitution solid solutions are formed (0 ≤ x ≤ 3) with the mineral kosnarite structure. The crystal structure of NaZr₂(AsO ₄)_1.5(PO₄)_1.5 was refined by full-profile analysis: space group R c, a = 8.9600(4)?, c = 22.9770(9) ?, V = 1597.5(1) ?³, R _wp = 4.55. The thermal expansion of the arsenate-phosphate NaZr₂(AsO₄) _1.5(PO₄)_1.5 and the arsenate NaZr ₂(AsO₄)₃ was studied by thermal X-ray diffraction in the temperature range of 20-800°C. The average linear thermal expansion coefficients (α_av = 2.45 × 10^-6 and 3.91 × 10^-6 K^-1, respectively) indicate that these salts are medium expansion compounds.

Full text of DOI:10.1134/S0036023611090294

ISSN 0036ꢀ0236, Russian Journal of Inorganic Chemistry, 2011, Vol. 56, No. 9, pp. 1351–1357. © Pleiades Publishing, Ltd., 2011.
Original Russian Text © M.V. Sukhanov, V.I. Pet’kov, D.V. Firsov, V.S. Kurazhkovskaya, E.Yu. Borovikova, 2011, published in Zhurnal Neorganicheskoi Khimii, 2011, Vol. 56,
No. 9, pp. 1423–1429.
SYNTHESIS AND PROPERTIES
OF INORGANIC COMPOUNDS
Synthesis, Structure, and Thermal Expansion
of Sodium Zirconium Arsenate Phosphates
a
a
a
b
b
M. V. Sukhanov , V. I. Pet’kov , D. V. Firsov , V. S. Kurazhkovskaya , and E. Yu. Borovikova
*
Nizhni Novgorod State University, pr. Gagarina 23, Nizhni Novgorod, 630950 Russia
*
* Moscow State University, Vorob’evy gory, Moscow, 119899 Russia
Received March 29, 2010
Abstract—Sodium zirconium arsenate phosphates NaZr (AsO ) (PO ) were synthesized by precipitation
4 3 – x
2
4
x
technique and studied by Xꢀray diffraction and IR spectroscopy. In the series of NaZr (AsO ) (PO ) , conꢀ
2
4
x
4 3 – x
tinuous substitution solid solutions are formed (
0
≤
x
≤
3
) with the mineral kosnarite structure. The crystal
= 8.9600(4)
, Rwp = 4.55. The thermal expansion of the arsenate–phosphate
structure of NaZr (AsO ) (PO ) was refined by fullꢀprofile analysis: space group
R3c,
a
Å, c =
2
4 1.5
= 1597.5(1)
4 1.5
3
22.9770(9)
Å,
V
Å
NaZr (AsO ) (PO ) and the arsenate NaZr (AsO ) was studied by thermal Xꢀray diffraction in the temꢀ
2
4 1.5
4 1.5
2
4 3
–6
perature range of 20–800
0 K , respectively) indicate that these salts are medium expansion compounds.
°C
. The average linear thermal expansion coefficients (
α
av
= 2.45 × 10 and 3.91 ×
–6
–1
1
DOI: 10.1134/S0036023611090294
The family of the mineral kosnarite KZr (PO4)3
,
The effect of the nature of the atom (size, elecꢀ
2
often called NZP after the first synthesized analog tronegativity) in the positions M1, M2, L, and the
with similar composition NaZr (PO ) , comprises
2
4 3
occupancies of the extraframework positions on the
thermal expansion of NZP phosphates is widely disꢀ
cussed in the literature; this gave rise to a set of empirꢀ
ical regularities of the thermal expansion of their latꢀ
tice, which allow targeted prediction of phosphates
compounds and solid solutions described by the crystalꢀ
p
–
chemical formula (M1) 1(M2)0 {[L (TO ) ] }
,
is
0
→
→
3
2
4 3
3
∞
p
–
where {[L (TO ) ] } is the structure framework (
р
2
4 3
3
∞
the framework charge) and (M1)0 1, (M2)0 are the
→
→
3
types of extraframework cationic positions with indiꢀ
cation of the number of occupied sites [1–3]. The kosꢀ with controlled, including ultrasmall thermal expanꢀ
narite structure framework KZr (PO ) is composed of sion [3]. The effect of the anionꢀforming atom T other
2
4 3
vertexꢀsharing isolated PO4 tetrahedra and ZrO6 octaꢀ than phosphorus on the thermal expansion of comꢀ
hedra [4]. The structural fragments [Zr (PO ) ] form
2
4 3
pounds with the kosnarite structure has not been studꢀ
ied. The issues of crystal chemical modeling and synꢀ
thesis of differentꢀanion compounds and solid soluꢀ
tions, the effect of anion substitutions on the practically
valuable properties of materials with the kosnarite
structure (ionic conductivity and magnetic, luminesꢀ
cence, and catalytic properties) remain topical.
columns extended along the
c axis. The potassium
atoms occupy extraframework positions M1 located
–
between the [Zr (PO ) ] fragments and have C.N. = 6.
2
4 3
The extraframework M2 cavities between the
Zr (PO4)3] columns are vacant in the kosnarite strucꢀ
[
2
ture.
Most of the studies dealing with the synthesis,
The similar chemical properties of phosphorus and
arsenic, which are located in the same Group of the
Mendeleev Table, the slight difference between the
As–O and P–O bond lengths in the AsO4 and PO4 tetꢀ
rahedra (1.69 and 1.53 Å, respectively) and electroneꢀ
gativities (2.1 and 2.2) allow one to hope for broad isoꢀ
morphism in the series of arsenate phosphates.
This work is devoted to the synthesis, structure
refinement, and elucidation of the fields of concentraꢀ
tion and temperature stability of compounds and solid
solutions of the kosnarite structural type and to study
2
4
x
4 3 –
1351

1352
SUKHANOV et al.
I
1
2
3
4
5
6
7
8
9
1
1
1
1
0
1
2
3
10
30
, deg
50
2
θ
Fig. 1. XꢀRay diffraction patterns of the arsenate phosphates NaZr (AsO ) (PO ) x: x = (1) 0, (2) 0.25, (3) 0.5, (4) 0.75, (5)
2
4
x
4 3 –
1
.0, (6) 1.25, (7) 1.5, (8) 1.75, (9) 2.0, (10) 2.25, (11) 2.5, (12) 2.75, (13) 3.0.
EXPERIMENTAL
It was planned to synthesize arsenate–phosphate
samples NaZr (AsO ) (PO ) with = 0, 0.25, 0.5,
.75, 1.0, 1.25, 1.5, 1.75, 2.0, 2.25, 2.5, 2.75, and 3.0
covering the whole range of existence of the putative
phases with the kosnarite structure. The synthesis was
carried out by the precipitation technique. For this
purpose, stoichiometric amounts of 1 M aqueous soluꢀ
tions of sodium nitrate and zirconium oxychloride
ZrOCl2 were mixed. Then stoichiometric amounts of
Powder Xꢀray diffraction patterns of the samples
were measured on an XRDꢀ6000 Xꢀray diffractometer
(
Cu
K
radiation,
λ
= 1.54178 Å, angle range
–50°). The Xꢀray diffraction spectrum for refining
structure of the arsenate–phosphate
2
θ
=
α
x
2
4
x
4 3 – x
10°
the
0
NaZr (AsO ) (PO ) was measured in the range of
2
4 1.5
4 1.5
angles
2
θ
= 10
°
–110° with a scanning step of 0.02 and
°
exposure of 2.5 s. The diffractogram processing and
structure refinement were performed by the Rietveld
method [16] using the RIETANꢀ97 program [17]. The
peak profiles were approximated using the modified
pseudoꢀVoigt function (ModꢀTCH pV [18]). As the
base model for refining the crystal structure of the
arsenate–phosphate, the atom coordinates of the
1
M phosphoric and 0.5 M arsenic acids were added
with stirring and heating. The solution of arsenic acid
was prepared by dissolving elemental arsenic with
heating in a solution of nitric and hydrochloric acids
present in 1 : 1 ratio (by volume).
3
arsenate NaZr (AsO ) (space group R c, the structural
2
4 3
type of kosnarite) were used [19]. The highꢀtemperaꢀ
ture measurements were carried out in the temperaꢀ
ture range of 25–800°С using the HAꢀ1001 Shimadzu
attachment. The heating rate was 10 K/min. Prior to
the measurements, the sample was kept at a specified
temperature for 10 min.
The mixtures obtained were dried at 90 and 270
°
С
and heat treated at 600 and 900 for 24 h. The stepꢀ
°
С
wise heating of the samples was alternated with disperꢀ
sion for maintenance of sample homogenization.
The chemical composition and uniformity of samꢀ
ples were determined by a CamScan MVꢀ2300 raster
electron microscope (VEGA TS 5130MM) equipped
with secondary and reflected electron YAG detectors
and energyꢀdispersive Xꢀray microanalyzer with a
Link INCA ENERGY 200C semiconductor Si(Li)
detector. For calculating the compositions, the PAP
correction method was used. The error of determinaꢀ
tion of the sample composition was not more than 2 at.
The functional composition of the samples was
confirmed by IR spectroscopic studies. IR absorption
spectra were recorded on an FSMꢀ1201 FT IR specꢀ
–1
troscopy in the wavelength range of 400–1400 cm .
RESULTS AND DISCUSSION
%
. The results of microprobe analysis showed that
The results of powder Xꢀray diffraction indicate
monophase arsenate–phosphate samples are uniform that in the NaZr (AsO ) (PO ) system, the crystal
2
4
x
4 3 – x
and consist of crystallites of size 1 to 20
position corresponds to the theoretical one to within 600
the inaccuracy of the method. 900
µ
m; their comꢀ phases with the kosnarite structure are formed at
°
С
. The increase in the annealing temperature to
°
С resulted in their higher crystallinity. The singleꢀ
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 9 2011

SYNTHESIS, STRUCTURE, AND THERMAL EXPANSION
1353
V
,
Å3
625
575
525
1
1
1
1
2
3
c, Å
23.0
22.9
22.8
4
5
a, Å
6
7
8
.95
.75
8
0
1
2
3
x
1200
1000
800
, cm–1
600
400
Fig. 2. Unit cell parameters of NaZr (AsO ) (PO )
vs.
2
4
x
4 3 –
x
ν
composition.
phase samples were obtained in the composition range
of 0.5 and 2.5 3.0. The compositions with
.0 2.5 are characterized, according to powder
Fig. 3. IR spectra of arsenate phosphates
NaZr (AsO ) (PO ) x: = ( ) 0, ( ) 0.5, ( ) 1.0, ( ) 1.5,
0
≤
х
х
≤
≤
х
≤
x
1
2
3
4
2
4
x
4 3 –
(5) 2.0, (6) 2.5, (7) 3.0.
1
≤
≤
Xꢀray diffraction, by the presence of two phases with
the kosnarite structure in the samples. Further
increases and the reaction rate grows. As the sintering
additive, we used ZnO (0.75 wt %).
increase in the annealing temperature to 950 С
°
resulted in the appearance of zirconium oxide reflecꢀ
tions in the Xꢀray diffraction patterns of all arsenicꢀ
containing samples.
The powders obtained by precipitation and annealed
at 800
annealed at 850–900
°
С
were mixed with ZnO, pressed at 300 MPa, and
for 24 h. The use of sintering
°С
According to the preliminary conclusion concernꢀ trace additive provided singleꢀphase sodium zirconium
ing the miscibility of phosphorus and arsenic in the arsenate–phosphate samples, NaZr (AsO ) (PO ) x,
2
4
x
4 3 –
arsenate–phosphate systems, one should expect broad over the whole range of compositions (Fig. 1). Powder
limits of isomorphous miscibility of NaZr (PO ) and Xꢀray diffraction analysis of the arsenate–phosphate
2
4 3
NaZr (AsO4)3, which contradicted the obtained experꢀ sample NaZr (AsO ) (PO ) pressed and annealed
2
2
4 1.5
4 1.5
imental data, apparently due to the low reactivity of under the same conditions but without zinc oxide
the solidꢀstate reactants. The solidꢀstate reaction can showed the presence of two NZP phases, as in the case
be initiated by trace additives able to change the conꢀ of synthesis without the sintering additive or pressing.
centrations of point and extended defects and thus
affect the diffusion processes and reactions at interꢀ
faces. In the case of NZP compounds, the metal oxide
The Xꢀray diffraction patterns of arsenate phosꢀ
phates show a smooth displacement of the diffraction
maxima with gradual change in their relative intensiꢀ
additives forming lowꢀmelting compounds ensure the ties upon increase in
х (Fig. 1). The calculated paramꢀ
active shrinkage of the pressed powders on heating and eters of their unit cells increase monotonically followꢀ
the formation of samples with nearly theoretical denꢀ ing an increase in the content of larger arsenic atoms
sity [20–22]. As a result, the contact surface between (compared to phosphorus atoms), which attests to the
the reacting particles in the solid reaction mixtures formation of continuos substitution solid solutions in
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 9 2011

1354
SUKHANOV et al.
Table 1. Details of the XꢀRay diffraction experiment and reꢀ spectra of the arsenate phosphates NaZr (AsO ) (PO ) x,
2
4
ν
3
x
4 3 –
sults of crystal structure refinement of NaZr (AsO ) (PO )
2
4 1.5
4 1.5 the selection rules allow five asymmetric
stretching
modes, one symmetric
ν
stretching mode, five asymꢀ
bending modes, and two symmetric
ing modes for each tetrahedral ion. The absorption
bands at 1020–1210 cm in the IR spectrum of
NaZr (PO ) ( = 0) are asymmetric stretching bands,
those at 550–650 cm are asymmetric P–O bending
modes in the PO4 tetrahedron. The symmetric stretchꢀ
ing modes are not manifested in the spectrum, while
the symmetric bending modes occur below 400 cm .
Out of the five bands allowed by the selection rules,
four bands were found in the spectrum, one with a
maximum at 1210 cm and three overlapping bands at
1
Space group
metric
ν
ν
2
bendꢀ
R
3
c
(no. 167)
6
4
–
1
Z
x
4 3
2
2
θ
range, deg
Unit cell parameters:
, Å
, Å
10–110
–1
–
1
a
8.9600(4)
22.9770(9)
1597.5(1)
227
ν
3
c
–1
, Å3
V
–
1
1
073, 1049, and 1022 cm . The highꢀfrequency band
–1
Number of reflections
Number of refined parameters:
structural
at 1210 cm , which is not typical of anhydrous phosꢀ
phates, comes from the contribution of the electron
4+
density of small highly charged Zr ion to the P–O
bond. The
ν
4
bending region has three bands (out of
five bands allowed by the selection rules) with maxima
at 648, 577, and 522 cm . The IR spectrum of the secꢀ
15
18
–1
other
ond terminal member of the series, NaZr (AsO ) , is
2
4 3
Reliability factors, %
characterized by considerable shift of all bands in both
vibration regions to lower frequencies, which is caused
by larger size and weight of the arsenic atom as comꢀ
pared with the phosphorus atom. The IR spectrum of
NaZr (AsO ) shows a doublet of intense highꢀfrequency
a
wp
b
p
R , R
4.55, 3.41
aR = {(
2
2 ½
Σ
wi
[
yi
–
wi
exp
yi ] /(Σ [yi ] )} .
wp
exp
calc
2
4 3
–1
bRp = (
Σ
|yiexp
–
yicalc|)/(Σyiexp).
bands at 1022 and 959 cm . The bending region conꢀ
tains one mediumꢀintensity band at 482 cm . The other
bands are apparently below 400 cm and cannot be
observed by the instrument used.
–1
–1
this system (Fig. 2). The dependences of the unit cell
parameters and of arsenate phosphates on the comꢀ
position are described by parabolic equations:
а
с
In the IR spectra of intermediate members of the
series, as the content of arsenic increases, the bands of
a
x
=
+
+
2
2
0
0
1
.0055
.1742
530.0 (
unit cell parameters from the Vegard’s rule are apparꢀ
x
+ 0.1079
x
+ 8.7941 (
0.007 ),
±
0.004
Å
),
c
= –0.0264
3−
–1
AsO4 ion appear at 876 and 500 cm and their intenꢀ
2
x
+ 22.842 (
±
Å
V
= 0.5586
x + 49.293x
3
−
3
sity increases. Simultaneously, the PO absorption
±
1
Å
). The deviations of the dependences of
4
bands shift to lower frequencies: the highꢀfrequency
–
1
–1
ently due to the flexibility of the structure framework band at 1210 cm shifts by ~100 cm , and the most
–1
and distortion of the anion packing of the solid soluꢀ intense
ν
band of the phosphate ion shifts by ~30 cm
3
tion as compared with the anion packing in the pure
components.
1049 cm–1
–1
(
→
1020 cm ). The bands of bending
ν
4
vibrations also shift to lower frequencies. On the other
3
−
IR spectra of the solid solutions of hand, the AsO4 bands shift to higher frequencies as
NaZr (AsO ) (PO ) are presented in Fig. 3. In the IR the arsenic content in the intermediate compounds
2
4
x
4 3 – x
Table 2. Coordinates and isotropic thermal parameters of atoms in the structure of NaZr (AsO ) (PO )
4 1.5
2
4 1.5
Atom
Position
x
y
z
B
, Å2
Na
Zr
6b
12c
18e
36f
36f
0
0
0
0
0
0
3.59(3)
0.48(5)
1.13(8)
0.6(2)
0.14450(5)
0.25
As, P
O1
0.2911(2)
0.1779(6)
0.1878(5)
–0.0171(6)
0.1617(5)
0.1903(6)
0.0866(2)
O2
0.4(1)
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 9 2011

SYNTHESIS, STRUCTURE, AND THERMAL EXPANSION
1355
I, rel. units
25000
20000
15000
10000
5000
0
–5000
10
30
50
70
90
110
, deg
2
θ
Fig. 4. Experimental (circles) and calculated (continuous line) Xꢀray diffraction spectra of NaZr (AsO ) (PO ) . The vertical
2
4 1.5
4 1.5
dashes show the positions of reflections of the theoretical Xꢀray diffraction pattern NaZr (AsO ) (PO4)1.5, the curve in the
2
4 1.5
lower part of the figure is the difference curve of the intensities of experimental and theoretical spectra.
decreases. Thus the doublet of principal
ν
bands of responds to the kosnarite type and is composed of tetꢀ
rahedra statistically occupied by arsenic and phosphoꢀ
3
3
−
–1
the AsO4 anion at 870, 853 cm is converted to one
–1
rus atoms and ZrО6 octahedra connected by vertices
band at 876 cm for compound with
х
= 0.5.
3
−
–
1
–1
TheAsO4 bending band at 482 cm shifts by ~20 cm
–1
to higher frequencies: 482
of the
the arsenate ion at 959 cm . The IR spectrum of the
arsenate phosphate with = 2.5 acquires the features
of the final member of the series, NaZr (AsO ) . The
→
500 cm . The spectrum Table 3. Selected interatomic distances and bond angles in
х
= 1.5 compound exhibits the second band of the polyhedra ZrO and (As,P)O in the structure of
6
4
–1
NaZr (AsO ) (PO )
2
4 1.5
4 1.5
х
2
4 3
Bond
d
, Å
Angle
ω
, deg
3
−
3−
smooth shifts of the PO and AsO4 anions to lower
4
and higher frequencies, respectively, attest to the forꢀ
mation of continuous substitution solid solutions in
the series of NaZr (AsO ) (PO ) x.
Na–O2 (
×
6)
3)
3)
2.540(4) O1(As,P) O1'
1.979(9) O1(As,P)O2 (
2.065(4) O1(As,P)O2 (
2) 1.667(12) O2(As,P)O2'
111.5(5)
2) 106.9(2)
2) 110.2(2)
111.2(2)
Zr–O1 (
×
×
2
4
x
4 3 –
Zr–O2 (
×
×
To confirm the structure of mixed sodium zircoꢀ
nium arsenate phosphates, the structure of
(As,P)–O1 (
×
NaZr (AsO ) (PO ) was studied by the Rietveld (As,P)–O2 (
×
2) 1.617(3) O1ZrO1' (
×
3)
94.4(2)
2
4 1.5
4 1.5
method. The experiment details, unit cell parameꢀ
ters, and structure refinement details are presented in
Table 1. The structure of the arsenate phosphate
NaZr (AsO ) (PO4)1.5, like that of the terminal memꢀ
O1ZrO2 (
O1ZrO2 (
O1ZrO2 (
×
3)
3)
3)
89.5(2)
×
92.7(2)
×
171.7(2)
2
4 1.5
bers of the series, NaZr (PO ) and NaZr (AsO ) , corꢀ
O2ZrO2' (
×
3)
82.9(2)
2
4 3
2
4 3
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 9 2011

1356
SUKHANOV et al.
The occupancy of the tetrahedral positions in
NaZr (AsO ) (PO ) by larger arsenic cations results
c
2
4 1.5
4 1.5
in expansion of the cell along crystallographic axes.
This is accompanied by deformation tetrahedra. The
a
b
(
P,As)–O1 bond length along the с axis is longer than
the bond lengths at the O2–(P,As)–O2 angle located
in the horizontal plane. This difference between the
interatomic distances is maximum for the arsenate–
phosphate NaZr (AsO ) (PO ) (0.05 Å) and less
ZrO6
Na
2
4 1.5
4 1.5
than 0.03 Å for the terminal members of the series,
NaZr (PO ) and NaZr (AsO4)3. The difference
(As, P)O4
2
4 3
2
between the bond lengths results in shortening of the
distance between the parallel columns along axis and
their stretching along the axis and accounts for the
deviation of the behaviors of the parameters and
а
с
а
с
from the Vegard’s law in the arsenate–phosphate
series.
The thermal expansion of the arsenate NaZr (AsO )
2
4 3
Fig. 5. Crystal structure of NaZr (AsO ) (PO ) .
4 1.5
2
4 1.5
and the arsenate–phosphate NaZr (AsO ) (PO )
2
4 1.5
4 1.5
was studied by thermal Xꢀray diffraction. An increase
in the temperature results in a decrease in the parameꢀ
V
,
Å3
1
ter
Fig. 6, Table 4), which is due to the correlated rotaꢀ
tion of the tetrahedra and octahedra around the axis
a of their cells and increase in the parameter с
(
1
1
1
670
c
typical of NZP compounds. The values of linear therꢀ
mal expansion coefficients of the arsenate
630
590
–
6
–6
NaZr (AsO ) are
α
= –6.65
×
10 , = 25.04
α
×
10 ,
2
2
= 3.91
4 3
a
с
–
6
–1
α
av
×
10 deg ; those for the arsenate–phosꢀ
–
6
phate NaZr (AsO ) (PO ) are
α
= –5.82
×
10 ,
2
×
4 1.5
α
4 1.5
a
–
6
10–6 deg . Both comꢀ
–1
c
,
Å
1
α
с
= 18.99
10 ,
av
= 2.45 ×
pounds can be classified as medium expansion comꢀ
pounds. An increase in the arsenic content in the comꢀ
pound results in increase in the absolute values of the
thermal expansion coefficients, which is attributable
to an increase in the bond lengths of the tetrahedral
atoms to oxygen and the bond ionicity and, as a conꢀ
sequence, lower strength at thermal deformations of
the crystal structure. The opposite directions of variaꢀ
tion of the cell parameters on heating results in a conꢀ
siderable anisotropy of the thermal expansion, which
increases with increase in the content of arsenic in the
2
2
2
3.5
3.3
3.1
2
a, Å
1
9
.11
–6
–1
compound: the
|
α
– с| value is 31.7 × 10 deg for
α
9
.01
.91
a
–6
–1
NaZr (AsO )
and 24.8
×
10
deg
for
2
4 3
NaZr (AsO ) (PO ) .
2
4 1.5
4 1.5
2
8
Thus, sodium zirconium arsenate phosphates
0
200
400
T, °C
600
800
NaZr (AsO ) (PO ) were synthesized by the precipꢀ
2
4
x
4 3 – x
itation method with addition of ZnO for sintering at
the final stage. In this system, continuous substitution
solid solutions with the kosnarite structure are formed.
The tetrahedral positions in the arsenate phosphates
are statistically occupied by phosphorus and arsenic
atoms. The highꢀtemperature Xꢀray diffraction studies
Fig. 6. Unit cell parameters of (
NaZr (AsO ) (PO ) vs. temperature.
1) NaZr (AsO ) and (2)
2 4 3
2
4 1.5
4 1.5
(
Table 2, Fig. 4, 5). The sodium atoms occupy the
extraframework M1 positions. The calculated bond of NaZr
lengths and angles are typical of phosphates and arsenꢀ to assign these compounds to medium expansion
ates with the kosnarite structure (Table 3). compounds.
(AsO )1.5(PO )1.5 and NaZr (AsO ) allow one
2
4 4 2 4 3
RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 9 2011

SYNTHESIS, STRUCTURE, AND THERMAL EXPANSION
1357
2
Table 4.
parameters (
р
=
p t + + p1t
2
+
) of NaZr (AsO ) (PO ) and
p0 polynomials for the unit cell
2
7. L. B. Goodenaugh H. Y.ꢀP. Hong, and J. A. Kafalas,
Mater. Res. Bull. 11 (2), 203 (1976).
8. A. K. IvanovꢀShits and I. V. Murin, SolidꢀState Ionics
a,
c
,
V
NaZr (AsO ) on temperature
4 1.5
4 1.5
2
4 3
(
St.ꢀPeterb. Gos. Univ., St. Petersburg, 2001), Vol. 1 [in
p2
NaZr (AsO ) (PO )
4 1.5
p1
p0
Russian].
9. D. Mazza, M. LuccoꢀBorlera, and S. Ronchetti, Powꢀ
2
4 1.5
10–6 –0.080
0.393
10–6 –1.399
10–3
10–3
10–3 1602.0
der Diffraction 13 (4), 227 (1998).
10. R. ShimanouchiꢀFutagami, M. Nishimori, and
a
c
(
±
0.002
0.008
Å
)
0.039
×
×
×
×
8.964
10–6
(
±
Å)
0.114
×
×
23.021
H. Nishizawa, J. Mater. Sci. Lett. 20, 1881 (2000).
V
(
±
1
Å3
)
21.613
1
1. V. I. Pet’kov, M. V. Sukhanov, and V. S. Kurazhꢀ
kovskaya, Radiokhimiya 45 (6), 560 (2003) [Radioꢀ
chemistry 45 (6), 620 (2003)].
12. M. V. Sukhanov, V. I. Pet’kov, V. S. Kurazhkovskaya,
et al., Zh. Neorg. Khim. 51 (5), 773 (2006) [Russ. J.
Inorg. Chem. 51 (5), 706 (2006)].
NaZr (AsO )
2
4 3
10–6 –0.077
a
c
(
±
0.002
0.014
0.7 Å3
Å)
0.013
0.095
×
×
×
×
×
×
10–3
10–3
10–3 1684.5
9.171
23.125
10–6
(
±
Å)
0.559
10–6 12.913
V
(
±
)
10.540
1
1
1
3. R. ShimanouchiꢀFutagami, M. Nishimori, and
H. Nishizawa, J. Mater. Sci. Lett. 19, 405 (2000).
ACKNOWLEDGMENTS
This work was supported by the Russian Foundaꢀ
tion for Basic Research, project no. 11ꢀ03ꢀ00032.
4. J. Alamo and R. Roy, J. Solid State Chem. 51 (2), 270
(1984).
5. E. Breval, H. A. McKinstry, and D. K. Agrawal, British
Ceram. Transact. 93 (6), 239 (1994).
1
6. H. M. Rietveld, Acta Crystallogr. 22, 151 (1967).
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RUSSIAN JOURNAL OF INORGANIC CHEMISTRY Vol. 56 No. 9 2011