Preparation and crystal structure of a new lithium bismuth oxide: LiBiO3

Article abstract of DOI:10.1006/jssc.1996.0319

A new lithium bismuth oxide was discovered during the investigation of low-temperature hydrothermal reactions of the hydrated sodium bismuth oxide, NaBiO₃ · nH₂O. This lithium bismuth oxide crystallizes in the orthorhombic system with the lattice parameters a = 8.8278(3), b = 4.9135(2), and c = 10.6914(3) A, space group Pccn, and Z = 8. The crystal structure was refined using neutron powder diffraction data giving final R factors of R_WP= 10.04, R_P = 7.64, R_E = 3.88, and R_I = 4.86%. The LiBiO₃ crystal structure is similar to that of LiSbO₃. Both structures can be considered as based on an array of hexagonally closed packed oxygen atoms with cations occupying two-thirds of the octahedral sites. In both structures, the LiO₆ octahedra share faces to form a continuous string. However, in the LiSbO₃ structure SbO₆ octahedra each share two edges forming a continuous zigzag chain whereas in the LiBiO₃ structure BiO₆ octahedra each share one edge only. Thus, the LiBiO₃ structure also resembles the cubic KBiO₃ structure, both structures being based on a dimer unit of the type Bi₂O₁₀ which shares corners forming a network having interstitial alkali cations. On heating to about 300°C, LiBiO₃ transforms to LiBiO₂ through evolution of oxygen and reduction of Bi⁵⁺ to Bi³⁺.

Full text of DOI:10.1006/jssc.1996.0319

JOURNAL OF SOLID STATE CHEMISTRY 126, 121–126 (1996)
ARTICLE NO. 0319
Preparation and Crystal Structure of a New Lithium
Bismuth Oxide: LiBiO3
N. Kumada, N. Takahashi, and N. Kinomura
Faculty of Engineering, Yamanashi University, Miyamae-cho 7, Kofu 400, Japan
and
A. W. Sleight
Department of Chemistry, Oregon State University, Corvallis, Oregon 97331-4003
Received December 27, 1995; in revised form June 27, 1996; accepted July 10, 1996
O3 и nH2O was unsuccessful (9). We have now discovered
a new lithium bismuth oxide, LiBiO3 , prepared through
investigation of low-temperature hydrothermal reactions of the a low-temperature hydrothermal reaction. The synthesis,
A new lithium bismuth oxide was discovered during the
hydrated sodium bismuth oxide, NaBiO3 ؒ nH2O. This lithium
bismuth oxide crystallizes in the orthorhombic system with the
lattice parameters a ؍ 8.8278(3), b ؍ 4.9135(2), and c ؍
crystal structure, and thermal stability of this new com-
pound are described in this paper.
˚
10.6914(3) A, space group Pccn, and Z ؍ 8. The crystal structure
EXPERIMENTAL
was refined using neutron powder diffraction data giving final
R factors of RWP ؍ 10.04, RP ؍ 7.64, RE ؍ 3.88, and RI ؍
4.86%. The LiBiO3 crystal structure is similar to that of LiSbO3 .
Both structures can be considered as based on an array of
hexagonally closed packed oxygen atoms with cations occu-
pying two-thirds of the octahedral sites. In both structures,
the LiO6 octahedra share faces to form a continuous string.
However, in the LiSbO3 structure SbO6 octahedra each share
two edges forming a continuous zigzag chain whereas in the
LiBiO3 structure BiO6 octahedra each share one edge only.
Thus, the LiBiO3 structure also resembles the cubic KBiO3 struc-
ture, both structures being based on a dimer unit of the type
Bi2O10 which shares corners forming a network having intersti-
tial alkali cations. On heating to about 300؇C, LiBiO3 transforms
to LiBiO2 through evolution of oxygen and reduction of Bi5؉
1. Sample Preparation and Characterization
The starting material of NaBiO3 и nH2O (Nacalai Tesque
Inc.) was placed in a Teflon lined autoclave (70 ml) with
LiOH and H2O (30 ml) and was heated at 120–200ЊC for
4 days. The molar ratio of the starting material to lithium
hydroxide was varied from 0.25 to 4. The solid products
were separated by centrifuging, washed with distilled wa-
ter, and dried at 50ЊC. The products were identified by X-
ray powder diffraction using CuKͰ radiation. To deter-
mine chemical composition, the products were dissolved
completely in concentrated HCl. The amount of sodium,
lithium, and bismuth in the solution was analyzed by atomic
absorption spectroscopy or induced coupled plasma spec-
troscopy. The specific gravity was measured with a pic-
nometer. The valence of bismuth was determined by iodo-
metric titrations. The thermal stability was investigated by
TG-DTA with a heating rate of 10Њ/min. The gases evolved
during TG-DTA measurements in flowing He were ana-
lyzed by mass spectrometry.
to Bi3؉.
1996 Academic Press, Inc.
INTRODUCTION
We have previously reported several new bismuth oxides
prepared by low-temperature hydrothermal reactions us-
ing hydrated sodium bismuth oxide, NaBiO3 и nH2O, as a
starting material (1–5). Some of these compounds contain
pentavalent bismuth which is an unusual oxidation state
for bismuth. There are three known lithium bismuth oxides
2. Crystal Structure Refinement
The structural refinement was carried out by neutron
containing pentavalent bismuth: Li3BiO4 (6), Li7BiO6 (7), powder diffraction data collected at intervals of 0.05Њ 2␪
˚
and Li5BiO5 (8). However, LiBiO3 has not been previously from 10.00Њ to 120.00Њ 2␪ using a wavelength of 1.8857 A
reported. An attempt to prepare LiBiO3 with the ilmenite- at 295 K on a high resolution powder diffractometer at
type structure by an ion-exchange reaction using NaBi the Brookhaven National Laboratory. As the sample used
121
0022-4596/96 $18.00
Copyright 1996 by Academic Press, Inc.
All rights of reproduction in any form reserved.

122
KUMADA ET AL.
data collection contained a small amount of unknown im-
purities, the peaks from them were excluded for the re-
finement. The data were refined using the Rietveld method
with the program RIETAN (10).
TABLE 2
Chemical Analysis for LiBiO3
Li2O
Bi2O5
Total
Calc.(wt%)
Obs.(wt%)
5.66
5.33
94.34
94.64
100.0
99.97
RESULTS AND DISCUSSION
Preparation
tion of Bi5 as described below. The calculated density
(7.55 g/cm3) for Z ϭ 8 agreed with the measured value
(7.39 g/cm3). Electrical resistivity measured by the two
probe method using a pressed compact showed a high
resistivity of about 106 ⍀ и cm at room temperature.
ϩ
Single phase LiBiO3 was obtained after 2 days at 120ЊC
using a molar ratio of Li/Bi ϭ 4. The color of this product
was brown. When the reaction temperature was 140ЊC,
Bi2O4 (5) was obtained. The X-ray powder pattern of
LiBiO3 can be indexed (Table 1) as orthorhombic and the
lattice parameters were determined to be a ϭ 8.8278(3),
Thermal Behavior
˚
b ϭ 4.9135(2), and c ϭ 10.6914(3) A on the course of the
Figure 1 shows the TG-DTA curves and temperature
dependence of gas evolution during TG-DTA measure-
ments. The TG curve indicates weight loss in three steps,
and only oxygen is evolved during the course of pyrolysis.
The observed total weight loss (6.09 wt%) agrees well with
the value (6.06 wt%) calculated on the assumption that
LiBiO3 converted to LiBiO2 by release oxygen due to com-
structural refinement. The results of the chemical analyses
are listed in Table 2. No sodium was detected, and the
mean valence of bismuth by iodometric titrations agreed
with that estimated from weight loss caused by the reduc-
TABLE 1
3
ϩ
plete reduction of Bi5ϩ to Bi . The X-ray powder pattern
of the sample heated up to 600ЊC was identified with that
of LiBiO2 (11). The large endothermic peak observed at
about 600ЊC in the DTA curve corresponds to melting of
the sample.
X-Ray Powder Pattern for LiBiO3
h
k
l
d(obs.)
d(calc)
I/I0
0
1
2
1
2
1
0
3
0
2
0
2
4
1
2
4
1
0
2
3
1
4
5
1
3
5
1
1
1
4
3
2
0
0
0
1
1
1
0
0
2
1
1
0
0
2
2
1
1
2
1
2
0
0
0
3
0
1
3
1
2
2
2
3
2
2
0
1
1
3
4
2
0
3
4
4
0
2
0
1
5
4
5
2
6
4
2
1
6
3
3
7
6
4
6
5
5.340
4.568
4.410
3.981
5.345
4.572
4.414
3.984
1.7
68.1
17.2
83.2
100.0
46.4
29.4
30.7
10.9
10.2
1.7
7.3
2.5
10.4
3.3
7.9
18.3
15.8
11.4
24.2
2.3
1.6
2.9
2.1
4.8
3.134
3.139
2.7412
2.6728
2.5780
2.4573
2.4149
2.3477
2.2864
2.2069
2.1657
2.1469
1.9785
1.9205
1.8103
1.7932
1.7801
1.7495
1.7028
1.6760
1.5938
1.5257
1.5067
1.4674
1.4403
1.4251
1.4002
1.2968
1.2465
2.7420
2.6727
2.5777
2.4566
2.4147
2.3478
2.2862
2.2068
2.1640
2.1465
1.9783
1.9139
1.8086
1.7917
1.7784
1.7465
1.7017
1.6764
1.5923
1.5241
1.5058
1.4674
1.4389
1.4235
1.3989
1.2951
1.2472
2.9
4.8
5.2
1.6
1.4
2.4
2.4
FIG. 1. TG-DTA curves and temperature dependence of gas evolu-
tion during TG-DTA measurement in a stream of He.

LITHIUM BISMUTH OXIDE
123
FIG. 2. Crystal structure of LiSbO3 . (a) Projection along the b axis and SbO6 octahedra. The rectangle denotes the unit cell. (b) Projection
along the a axis.
Derivation and Description of the Structure
Pnna (No. 52). Nevertheless, comparison of the lattice
parameters of LiBiO3 and LiSbO3 suggested some similar
structural features. The structure of LiSbO3 is projected
along the bSb axis in Fig. 2a and along the aSb axis in Fig.
2b. Using this structure as a guide, a structural model for
LiBiO3 was derived where two BiO6 octahedra share edges
in the ac plane. The problem of periodicity along the c
axis was solved by connecting two edge-sharing octahedra
at the same height along the bBi axis with another pair of
edge-sharing octahedra at the different height along this
axis. On the other hand, in the LiSbO3 structure, pairs of
octahedra are repeated at the same height along the bSb
The lattice parameters of LiBiO3 (aBi ϭ 8.828, bBi
ϭ
˚
4.914, and cBi ϭ 10.691 A) appeared related to those of
˚
LiSbO3 (aSb ϭ 5.183, bSb ϭ 4.893, and cSb ϭ 8.491 A) with
Bi Ȃ cSb , bBi Ȃ bSb , and cBi Ȃ 2aSb (12). Diffraction peaks
a
appear at similar d values for both compounds, but the
intensities differ. The space group Pccn (No. 56) for LiBiO3
was deduced from the systematic absence of reflections
with l ϭ 2n ϩ 1 for 0kl, l ϭ 2n ϩ 1 for h0l, and h ϩ k ϭ
2n ϩ 1 for hk0 as shown in Table 1. These extinction
conditions differ from those of LiSbO3 with space group
FIG. 3. Observed (dots), calculated (solid line), and difference (at the bottom) neutron diffraction profiles for LiBiO3 .

124
KUMADA ET AL.
TABLE 3
Crystal Data and Intensity Collection
for LiBiO3
TABLE 5
Selected Interatomic Distances (A) for LiBiO3
˚
BiO6 octahedra
LiO6 octahedra
Color
Brown
Bi–O(1) 2.12(2)
Li–O(1)
1.91(7)
2.01(6)
1.98(7)
2.51(6)
2.34(6)
2.02(7)
2.13
Crystal system
Space group
Z
Orthorhombic
Pccn (No. 56)
8
O(1)
O(2)
O(2)
O(3)
O(4)
mean
2.12(2)
2.09(2)
2.09(2)
2.07(2)
2.14(2)
2.11
O(1)
O(2)
O(2)
O(3)
O(4)
mean
Lattice parameters a ϭ 8.8278(3), b ϭ 4.9135(2)
˚
c ϭ 10.6914(3) A
3
˚
Volume
463.74 A
263.90
Formula weight
Calculated density
Wavelength
Temperature
2␪ scan range
RWP
RP
RE
RI
7.56 g/cm3
˚
O(1)–O(1)
O(1)–O(2)
O(1)–O(2)
O(1)–O(2)
O(1)–O(3)
O(1)–O(4)
O(1)–O(4)
O(2)–O(2)
O(2)–O(3)
O(2)–O(3)
O(2)–O(4)
O(3)–O(4)
mean
2.72(4)
2.88(2)
3.04(3)
3.15(3)
3.09(3)
2.77(2)
3.05(2)
3.03(2)
2.91(2)
2.92(2)
3.08(3)
3.04(2)
2.97
O(1)–O(1)
O(1)–O(2)
O(1)–O(2)
O(1)–O(3)
O(1)–O(4)
O(1)–O(4)
O(2)–O(2)
O(2)–O(3)
O(2)–O(3)
O(2)–O(4)
mean
2.80(4)
2.88(2)
3.09(2)
2.95(3) ϫ 2
2.77(2)
3.19(2)
3.01(4)
3.12(2)
2.91(2)
2.05(3) ϫ 2
2.98
␭ ϭ 1.8857 A
23ЊC
10.00–120.00Њ
10.04%
7.64%
3.88%
4.86%
axis to form a continuous zigzag chain along the aSb axis.
The structural model developed for LiBiO3 is consistent
with the space group Pccn (No. 56). The crystal structure
of LiBiO3 was refined based on this starting model, and
the final agreement factors were RWP ϭ 10.04, RP ϭ 7.64,
RE ϭ 3.88, and RI ϭ 4.86%. Figure 3 shows observed and
calculated neutron diffraction patterns. The crystallo-
graphic data are summarized in Table 3. Tables 4 and
5 show the atomic parameters and selected interatomic
distances, respectively. The crystal structure of LiBiO3 and
the coordination environment around bismuth and lithium
atoms are shown in Figs. 4 and 5. The bismuth atom is
octahedrally coordinated by six oxygens at mean distances
Bi–Bi
3.26(2)
Li–Li
2.5(2)
The difference in the crystal structures of LiBiO3 and
LiSbO3 is seen by comparing Fig. 4 with Fig. 2. The pairs
of edge-sharing BiO6 octahedra at y Ȃ 1/4 and 3/4 alternate
along the cBi axis, and every adjacent pair is at different
height in LiBiO3 . On the other hand, in LiSbO3 edge-
sharing SbO6 octahedra at the same height form continu-
ous zigzag chains along the aSb axis.
The structures of LiBiO3 and cubic KBiO3 may both be
considered as based on edge-shared BiO6 octahedra units
which in turn share corners with each other. The geometry
of the dimer unit is essentially the same in the two different
structures. In both cases, the Bi atoms of the unit are
displaced away from each other relative to ideal octahedra.
5
ϩ
of 2.11, and these values agree well with the mean Bi –O
˚
˚
distances of 2.10 A in KBiO3 (13) and 2.101 A in Bi2O4
(5). In both the structures of LiBiO3 and LiSbO3 , the LiO6
octahedra share faces continuously along the b axis. The
Li–O distances are ranged from 1.91(7) to 2.51(6) A and
the distances 2.34(5) and 2.5(6) A for Li–O(3) and Li–O(2)
are longer than those of the others. The position of the
lithium atom is slightly deviated from the center of the octa-
hedron.
˚
˚
˚
Ideal octahedra with a Bi–O distance of 2.10 A would give
a Bi–Bi distance of 2.97 A instead of the 3.26 and 3.21
A Bi–Bi distances actually observed in both LiBiO3 and
˚
˚
KBiO3 . Although the same building blocks are used to
form the covalent network of the structures, the KBiO3
network is much more open. Comparing the unit cell vol-
umes of LiBiO3 and KBiO3 shows that in fact the KBiO3
network occupies 45% more space. The channels in the
KBiO3 structure can accommodate cations as large as Rbϩ
whereas those of LiBiO3 may not be able to accommodate
cations larger than Liϩ.
TABLE 4
2
˚
Positional and Thermal Parameters (A ) for LiBiO3
Atom
Site
x
y
z
Beq
Bi
Li
O(1)
O(2)
O(3)
O(4)
8e
8e
8e
8e
4c
4d
0.414(1)
0.783(5)
0.406(2)
0.420(2)
1/4
0.006(3)
Ϫ0.004(17)
0.302(3)
0.776(3)
1/4
0.3647(8)
0.402(4)
0.043(2)
0.200(2)
0.285(3)
0.952(3)
0.4(2)
2(1)
1.1(4)
0.4(4)
0.8(7)
0.4(6)
The lithium bismuth oxide LiBiO3 obtained here is the
only one which has not been prepared in Aϩ M5ϩ O3 com-
positions (A ϭ Li, Na, K; M ϭ Nb, Ta, Sb, Bi) (14). The
1/4
3/4

LITHIUM BISMUTH OXIDE
125
FIG. 4. Crystal structure of LiBiO3 . (a) Projection along the b axis and BiO6 octahedra. The rectangle denotes the unit cell. (b) Projection
along the c axis.
5
ϩ
crystal structures for Aϩ M O3 compounds are listed in pounds: NaNbO3 by low-temperature hydrothermal reac-
Table 6. The fact that the crystal structure of LiBiO3 is tion (15) and LiNbO3 by ion-exchange reaction of the
closely related to that of LiSbO3 but not to the LiNbO3- former (16). Metastable phases which are new in structure
type structure is consistent with general features pointed or composition have been prepared very often by low-
out by Goodenough and Kafalas (14) of the crystal struc- temperature hydrothermal reactions or by ion-exchange
5
ϩ
tures for Aϩ M O3 compounds. We have reported the reactions. The compound of LiBiO3 might exist as a stable
preparation of metastable ilmenite-type niobates which are phase under sufficient oxygen pressure, as its structure
5
in contrast to the general features of Aϩ M5 O3 com- follows the general features of Aϩ M O3 compounds.
ϩ
ϩ
CONCLUSION
Using a low-temperature hydrothermal method, a new
lithium bismuth oxide, LiBiO3 , was prepared for the first
TABLE 6
Crystal Structures of A؉ M5؉ O3 Compositions
M
A
Nb
Ta
Sb
Bi
Li
LiNbO3
LiNbO3
LiSbO3
LiBiO3
ilmenite (16)
perovskite
ilmenite (15)
perovskite
ilmenite (9)
ilmenite
(this work)
ilmenite
Na
K
perovskite
perovskite
ilmenite
KBiO3
FIG. 5. Coordination environment around Bi and Li atoms.

126
KUMADA ET AL.
time. This had been the only missing member of the Aϩ
4. N. Kinomura and N. Kumada, Mater. Res. Bull. 30, 129 (1995).
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Solid State Chem. 116, 281 (1995).
6. G. Blasse, Z. Anorg. Allg. Chem. 331, 44 (1964).
7. E. Nomura and M. Greenblatt, J. Solid State Chem. 52, 91 (1984).
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10. F. Izumi, Kobutsugaku Zasshi 17, 37 (1985).
M5 O3 family where A ϭ Li, Na, or K and where M ϭ
ϩ
Nb, Ta, Sb, or Bi. The crystal structure of LiBiO3 has
features in common with both LiSbO3 and KBiO3 . At
temperatures higher than about 300ЊC, LiBiO3 decom-
3
poses into LiBiO2 by complete reduction of Bi5 to Bi .
ϩ
ϩ
11. R. Hoppe and B. Scwedes, Rev. Chim. Miner. 8, 583 (1971).
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(1984).
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