Single crystal growth and characterization of a new bismuth indium niobate compound, Bi5In2Nb3O18-x

Article abstract of DOI:10.1016/S0925-8388(99)00214-5

Single crystals of a new bismuth indium niobate, Bi₅In₂Nb₃O_18-x, were grown by subsolidus reaction method. Differential thermal analysis measurements indicate that the compound has a melting point of 1224 °C. Single crystal and powder X-ray diffraction methods show that the compound has the tetragonal system; P4/mbm space group, and lattice constants are a = 12.6548(5), and c = 3.9231(3) angstroms. The magnetic susceptibilities of compound Bi₅In₂Nb₃O_18-x indicate Curie-Weiss behavior with an effective magnetic moment μ_eff = 0.72(1) μ_B.

Full text of DOI:10.1016/S0925-8388(99)00214-5

Journal of Alloys and Compounds 292 (1999) 72–76
L
Single crystal growth and characterization of a new bismuth indium
niobate compound, Bi In Nb O
5
2
3
182x
a
b ,
*
Zhigang Zou , Jinhua Ye
a
Electrotechnical Laboratory, 1-1-4 Umezono, Tsukuba, Ibaraki 305, Japan
b
National Research Institute for Metals, 1-2-1 Sengen, Tsukuba, Ibaraki 305, Japan
Received 20 March 1999; received in revised form 29 April 1999; accepted 29 April 1999
Abstract
Single crystals of a new bismuth indium niobate, Bi In Nb O182x, were grown by subsolidus reaction method. Differential thermal
5
2
3
analysis measurements indicate that the compound has a melting point of 12248C. Single crystal and powder X-ray diffraction methods
˚
show that the compound has the tetragonal system; P4/mbm space group, and lattice constants are a 5 12.6548(5), and c53.9231(3) A.
The magnetic susceptibilities of compound Bi In Nb O indicate Curie–Weiss behavior with an effective magnetic moment
5
2
3
182x
meff 5 0.72(1) mB
 1999 Published by Elsevier Science S.A. All rights reserved.
Keywords: Bi In Nb O182x; Single crystal; Magnetic moment; Crystal structure
5
2
3
1
. Introduction
Up to now, several different compounds, InNbO [1],
tion methods. The magnetic and thermal properties for
Bi In Nb O compound were investigated by magnetic
susceptibility and differential thermal analysis (DTA)
measurements.
5
2
3
182x
4
Bi Nb O [2], Bi InO [3] and Bi In O [4], have
5
3
15
35
54
60
2
98
been reported for the In–Nb–O, Bi–Nb–O, and Bi– In–O
systems, respectively. For the Bi–In–Nb–O system, how-
ever, only a ternary oxide compound, Bi InNbO [5], was
2. Experimental
2
7
reported. The Bi InNbO compound has a pyrochlore-type
2
7
structure at room temperature, but the space group and
lattice constants have not been reported [5]. It is known
that numerous compounds with the pyrochlory structure
exhibit antiferroelectric phases or dielectric anomalies,
only a few compounds exhibit a ferroelectric behavior [6].
The detailed analysis shows that most niobate compounds
consist of the three-dimensional network of NbO6 and
have interesting non-linear optical properties [7–9]. In
order to gain a better understanding of the physical
properties of niobate compounds such as magnetic and
electrical properties, it is important to grow single crystals
for structural studies of ternary niobate compounds.
Bi In Nb O
single crystals were grown by a sub-
182x
5
2
3
solidus reaction method using high purity Bi O (99.9%),
2
3
ln O (99.9%), and Nb O (99.9%) under ambient pres-
2
3
2
5
sure. Fig. 1 shows a schematic procedure of single crystal
growth in this work. First of all, Bi O , In O , and Nb O
were converted into Bi(NO ) , In(NO ) , and Nb(NO ) ,
respectively, using HNO (16N) at 608C. The solutions
were mixed and stirred well, then NH OH (7.5 N) was
added to the mixed solution. A precipitate was obtained
from the mixed solution. The precipitate was dried at about
2008C in air, and calcined in a furnace at 9008C for 10 h.
Then the calicined material was pressed into a pellet,
placed in a Pt crucible and inserted into the vertical
furnace. The furnace was heated from room temperature to
13008C over 20 h held at 13008C for 10 h and slowly
cooled to 6508C at a cooling rate 18C/h, then rapidly
cooled to room temperature. The single crystals of light
yellow color were obtained.
2
3
2
3
2
5
3
3
3
3
3 5
3
4
In this paper, we report the growth of a new ternary
bismuth indium niobate single crystal Bi In Nb O182x. To
5
2
3
characterize the new single crystal, the compound was
analyzed by the single crystal and powder X-ray diffrac-
*
Corresponding author. Tel.: 181-298-59-2731; fax: 181-298-59-
701.
E-mail address: ye@nrim.go.jp (J. Ye)
The chemical composition of the crystals was deter-
mined by scanning electron microscope– X-ray energy
2
0
925-8388/99/$ – see front matter
 1999 Published by Elsevier Science S.A. All rights reserved.
PII: S0925-8388(99)00214-5

Z. Zou, J. Ye / Journal of Alloys and Compounds 292 (1999) 72–76
73
Fig. 2. SEM photograph of Bi In Nb O single crystals.
182x
5
2
3
dispersion spectrum (SEM–EDS) with an accelerating
voltage of 25 kV. Thermal measurements of the
Bi In Nb O were performed by differential thermal
5
2
3
182x
and thermogravimetry analysis (DT–TGA). Single crystal
X-ray diffraction using a precession camera and an AFC-
5
0
R four-circle diffractometer (MoKa radiation, l5
.71073 A) were performed to determine the crystal
˚
structure and lattice constants. Powder X-ray diffraction
was carried out by an X-ray diffractometer with CuKa
˚
radiation (l5l.5418 A). Magnetic susceptibility was mea-
sured using a Superconducting Quantum Interference
Device (SQUID) magnetometer.
Fig. 1. Schematic diagram of the synthetic procedure for
Bi In Nb O
5
2
3
182x.
Fig. 3. Powder X-ray diffraction pattern of 2u510.0|60.0 for Bi In Nb O18-x. The reflection index peak is given with the attached number in Table 1.
5
2
3

7
4
Z. Zou, J. Ye / Journal of Alloys and Compounds 292 (1999) 72–76
3
. Results and discussion
Bi:In:Nb54.95(3):2.11(2):3:00(1) was obtained as an
average of measurements made at several different points.
Oxygen content was calculated from the EDS results [5].
Single crystal and powder X-ray diffraction measure-
ments were used to determine the crystal structure and
lattice constants of these single crystals. Precession photos
A typical SEM photograph of Bi In O single crys-
182x
tals grown by the subsolidus reaction method is shown in
5
2
Fig. 2. The crystals with the maximum size of |1.531.03
3
0
.6 mm were obtained from crystalline pieces of the
crushed subsolidus product. The chemical component of
Bi In Nb O single crystal was determined using
of Bi In Nb O
single crystal showed 4/mmm Laue
5
2
3
182x
symmetry. Single crystal intensity data were collected on a
four-circle AFC-SR diffractometer. Automatic peak search
and indexing procedures yielded a primitive tetragonal cell
which was used for all further work. The lattice constants,
5
2
3
182x
characteristic X-rays of NbLa, InLa, and BiMa. The
composition content was decided using the ZAF quantifi-
cation method. The SEM–EDS analysis showed that the
crystal has a homogenous atomic distribution with no other
additional elements. As a result, the atomic ratio of
˚
a512.6548(5) and c53.9231(3) A, were refined by the
least-squares method using 25 reflections with 2u .408.
Systematic absences for the reflections of okl, k52n11;
hol, h52n11 were observed and no other special abs-
ences exist. As a result, the structure is revealed to be a
tetragonal system with space group P4/mbm. The detailed
crystal structure will be published elsewhere [10].
Powder X-ray diffraction patterns were also analyzed
using the obtained bulk specimen. The indexed powder
X-ray diffraction pattern of the Bi In Nb O sample is
Table 1
Comparison of observed and calculated dhkl values of Bi In Nb O
based on the powder X-ray diffraction pattern shown in Fig. 3
5
2
3
182x
a
No.
h
k
l
2uobs
dobs
dcalc
I
1
2
3
4
5
6
7
8
9
0
1
2
3
4
5
6
7
8
9
0
1
2
3
2
2
0
1
3
2
2
4
4
3
2
4
3
0
1
0
1
2
0
1
0
1
3
2
2
1
–
2
0
3
1
1
2
0
3
0
1
5
2
4
2
3
0
–
1
3
1
5
–
2
4
1
0
0
1
1
0
1
1
0
0
0
1
0
1
13.98
15.64
22.54
24.72
25.36
26.70
27.64
28.18
28.96
29.98
30.24
31.60
31.88
33.56
34.24
36.70
41.58
43.06
44.00
45.28
46.20
48.20
48.98
6.3293
5.6611
3.9413
3.5984
3.5090
3.3359
3.2245
3.1640
3.0805
2.9780
2.9530
2.8289
2.8047
2.6680
2.6166
2.4466
2.1701
2.0989
2.0562
2.0010
1.9632
1.8864
1.8581
6.3286
5.6604
3.9246
3.5940
3.5 105
3.3351
3.2250
3.1643
3.0698
2.9833
2.9505
2.8302
2.8021
6
3
3
9
11
3
14
2
100
2
5
2
3
182x
shown in Fig. 3. It can be seen that almost all of the
diffraction peaks were successfully indexed based on the
lattice constants and the space group determined by single
crystal measurements. Only three reflections of I,1 could
not be indexed. These very weak peaks may be contributed
to the very small impurity phases. The observed and
calculated dhkll values are given in Table 1. The refined
lattice constants with the data of Table 1 are a512.657(3),
1
1
1
1
1
1
1
1
1
1
2
2
2
2
9
17
22
,1
5
3
7
2
2
8
˚
c53.924(1) A. The result is in a good agreement with
those of single crystal X-ray diffraction.
Fig. 4 shows DTA curves of Bi In Nb O single
crystal. DTA analysis of Bi In Nb O182x was carried out
5 2 3
3
4
5
5
6
6
0
6
6
7
5
6
5
3
6
4
1
1
0
1
0
0
2
0
1
0
0
1
1
2
1
2
2.6164
2.4633
2.1707
2.0978
5
2
3
182x
from 258C to 13008C with heating rate 58C/min in air. The
a-Al O was used as a standard. The DTA curve exhibits
2
3
2.0013
1.9621
1.8868
1.8581
1.7900
1.7900
1.7828
1.7654
1.7128
1.7005
1.6676
a clear endothermic peak at 12248C and an exothermic
peak at 1223.68C. Thus it is concluded that the congruent
melting point of Bi In Nb O182x crystals is 12248C and
15
51
4
5 2 3
2
2
2
2
2
2
3
3
3
3
4
5
6
7
8
9
0
1
2
3
50.98
51.12
51.74
53.46
53.86
55.00
55.16
55.54
55.70
56.46
1.7898
1.7852
1.7653
1.7125
1.7007
1.6681
1.6637
1.6532
1.6488
1.6284
9
6
3
1
3
2
,1
3
2
9
4
3
7
5
2
2
1
1
1.6533
1.6394
1.6286
1.6286
3
3
4
5
56.64
1.6237
,1
4
6
5
2
1
2
1.6125
1.6023
1.5393
57.22
60.00
1.6086
1.5405
40
9
3
6
a
The intensities Iobs are normalized by the strongest reflection.
Calculation was performed on the basis of a tetragonal unit cell with
˚
space group P4/mbm, a512.657(3) and c53.924(1) A which were
Fig. 4. The results of DTA for Bi In Nb O182x. Initial weight of sample
5 2 3
obtained by least-squares refinements [8] using powder X-ray diffraction
data with l51.54050 A.
is 10.00 mg, heating and cooling rates of the temperature are 5.08C/min,
and a thermocouple of Pt–PtRh13% was used.
˚

Z. Zou, J. Ye / Journal of Alloys and Compounds 292 (1999) 72–76
75
the congruent crystallizing point is 1223.68C. It is noted
that a slight difference between the melting and crys-
tallizing points is obtained from endothermic and ex-
othermic peaks. This difference may be contributed to the
instrumental error of DTA measurement. The result sug-
and Matsuura et al. [11,12]. The effective magnetic
moments of K Nb14,13P8.87O60 and K6.10Ba0.63Nb P O
are 0.98 and 1.30, which are smaller than that of theoret-
ical value [11]. In order to make clear the origin of the
unusual magnetic properties, further magnetic structure
analysis seems to be necessary. The study of the electrical
7
14
9
60
gests that Bi In Nb O crystal is a concordant fused
5
2
3
182x
compound, and has identical melting and crystallizing
points.
properties of Bi In Nb O
believed to supply more concrete information of localized/
delocalized electrons in the compound.
In conclusion, we prepared single crystal samples of a
new bismuth indium niobate, Bi In Nb O182x, by sub-
solidus reaction method, and investigated its structural,
magnetic and thermal properties. Single crystal and pow-
der X-ray diffractions showed that the compound has the
tetragonal system; P4/mbm space group, and lattice con-
is also in progress, which is
5
2
3
182x
The temperature-dependent molar magnetic suscep-
tibility of a batch of randomly oriented Bi In Nb O
5
2
3
182x
single crystals is shown in Fig. 5. Magnetic susceptibility
data were measured up to 0.5 Tesla in the temperature
range between 5 K and 300 K. The magnetic susceptibility
in the temperature range could be fit to a modified Curie–
5
2
3
Weiss relation according to the equation, x 5 x 1 C/(T 1
0
˚
Q), where x0 is temperature-independent contributions
such as Van Vleck and Pauli magnetism, C is the Curie
constant, and Q is the Curie–Weiss temperature. A non-
linear least-squares fitting of the observed data yielded
stants are a512.6548(5), and c53.9231(3) A. The tem-
perature dependence of the magnetic susceptibility shows
Curie–Weiss behavior, with considerably smaller effective
magnetic moment than the theoretical value. These results
are consistent with the presence of localized/delocalized
electrons. The thermal analysis suggests that
2
3
Q520.4(l) K and x 522.55310 emu/mol. A plot of
0
l/(x 2 x ) as a function of temperature is nearly linear in
0
the temperature range (see Fig. 5). We obtained an
Bi In Nb O
crystal is a concordant fused compound,
5
2
3
182x
4
1
effective magnetic moment of m 50.72(1) m /Nb (as-
and has identical melting and crystallizing points. Because
the compound can be grown easily as a single crystal or
single phase and without the need for other special
conditions, we believe that the compound will be useful as
a standard in research of the chemical state of niobium in
niobate compounds.
eff
B
suming spin-only contribution). The effective magnetic
moment is much smaller than the theoretical value of 1.73
for a spin-only one electron system [11]. This means that
only a little fraction of the charge carriers are localized,
while the major fraction might be delocalized. In fact, the
deviations from the expected effective magnetic moment in
other niobate compounds were also reported by Xu et al.
The authors would like to thank Professor Y. Nishihara
for his valuable discussion.
Fig. 5. Temperature dependence of the magnetic susceptibility of the Bi In Nb O compound. The solid lines represent fits of the data to the
182x
5
2
3
Curie–Weiss law.

7
6
Z. Zou, J. Ye / Journal of Alloys and Compounds 292 (1999) 72–76
[
[
[
[
6] G.I. Golovshchikove, V.A. Isupov, A.G. Tutov, I.B. Mylnikove, P.A.
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