X-ray investigations of phase transition in Bi₂TeO₅ single crystals
This work is devoted to researching a phase transition in bismuth tellurite single crystals using a high-temperature X-ray analysis method. The cell parameter step-wise changes at 805 ◦C are revealed. Starting from the data obtained we can say that the first-type transition takes place in bismuth te...
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Інститут фізики конденсованих систем НАН України
1999
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| Schriftenreihe: | Condensed Matter Physics |
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| Zitieren: | X-ray investigations of phase transition in Bi₂TeO₅ single crystals / K.V. Domoratsky, E.F. Dudnik, V.F. Katkov, L.Ya. Sadovskaya // Condensed Matter Physics. — 1999. — Т. 2, № 4(20). — С. 591-594. — Бібліогр.: 5 назв. — англ. |
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irk-123456789-1205892017-06-13T03:05:15Z X-ray investigations of phase transition in Bi₂TeO₅ single crystals Domoratsky, K.V. Dudnik, E.F. Katkov, V.F. Sadovskaya, L.Ya. This work is devoted to researching a phase transition in bismuth tellurite single crystals using a high-temperature X-ray analysis method. The cell parameter step-wise changes at 805 ◦C are revealed. Starting from the data obtained we can say that the first-type transition takes place in bismuth tellurite. Ця робота присвячена дослiдженню фазового переходу в монокристалах телуриту вiсмуту методом високотемпературного рентгеноструктурного аналiзу. Виявленi стрибкоподiбнi змiни параметрiв комiрки при 805 ◦С. Виходячи з отриманих даних, можна казати, що у телуритi вiсмуту має мiсце фазовий перехiд 1-го роду. 1999 Article X-ray investigations of phase transition in Bi₂TeO₅ single crystals / K.V. Domoratsky, E.F. Dudnik, V.F. Katkov, L.Ya. Sadovskaya // Condensed Matter Physics. — 1999. — Т. 2, № 4(20). — С. 591-594. — Бібліогр.: 5 назв. — англ. 1607-324X DOI:10.5488/CMP.2.4.591 PACS: 61.50.K http://dspace.nbuv.gov.ua/handle/123456789/120589 en Condensed Matter Physics Інститут фізики конденсованих систем НАН України |
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This work is devoted to researching a phase transition in bismuth tellurite single crystals using a high-temperature X-ray analysis method. The cell parameter step-wise changes at 805 ◦C are revealed. Starting from the data obtained we can say that the first-type transition takes place in bismuth tellurite. |
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Article |
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Domoratsky, K.V. Dudnik, E.F. Katkov, V.F. Sadovskaya, L.Ya. |
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Domoratsky, K.V. Dudnik, E.F. Katkov, V.F. Sadovskaya, L.Ya. X-ray investigations of phase transition in Bi₂TeO₅ single crystals Condensed Matter Physics |
| author_facet |
Domoratsky, K.V. Dudnik, E.F. Katkov, V.F. Sadovskaya, L.Ya. |
| author_sort |
Domoratsky, K.V. |
| title |
X-ray investigations of phase transition in Bi₂TeO₅ single crystals |
| title_short |
X-ray investigations of phase transition in Bi₂TeO₅ single crystals |
| title_full |
X-ray investigations of phase transition in Bi₂TeO₅ single crystals |
| title_fullStr |
X-ray investigations of phase transition in Bi₂TeO₅ single crystals |
| title_full_unstemmed |
X-ray investigations of phase transition in Bi₂TeO₅ single crystals |
| title_sort |
x-ray investigations of phase transition in bi₂teo₅ single crystals |
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Інститут фізики конденсованих систем НАН України |
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1999 |
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http://dspace.nbuv.gov.ua/handle/123456789/120589 |
| citation_txt |
X-ray investigations of phase transition in Bi₂TeO₅ single crystals / K.V. Domoratsky, E.F. Dudnik, V.F. Katkov, L.Ya. Sadovskaya // Condensed Matter Physics. — 1999. — Т. 2, № 4(20). — С. 591-594. — Бібліогр.: 5 назв. — англ. |
| series |
Condensed Matter Physics |
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2025-07-08T18:11:03Z |
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2025-07-08T18:11:03Z |
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1837103333157896192 |
| fulltext |
Condensed Matter Physics, 1999, Vol. 2, No. 4(20), pp. 591–594
X-ray investigations of phase transition
in Bi2TeO5 single crystals
K.V.Domoratsky, E.F.Dudnik, V.F.Katkov, L.Ya.Sadovskaya
Dnipropetrovsk State University,
20 Kazakova Str., 320625 Dnipropetrovsk, Ukraine
Received October 12, 1998
This work is devoted to researching a phase transition in bismuth tellurite
single crystals using a high-temperature X-ray analysis method. The cell
parameter step-wise changes at 805 ◦C are revealed. Starting from the
data obtained we can say that the first-type transition takes place in bismuth
tellurite.
Key words: phase transition, bismuth tellurite, X-ray, diffraction maxima
PACS: 61.50.K
Authors [1] consider that bismuth tellurite Bi2TeO5 (BTO) possesses ferroelectric
properties having undergone the second-type phase transition (PT) at the tempera-
ture about 780 ◦C. BTO has Abm2 orthorhombic lattice a=11.602 Å, b=16.461 Å,
c=5.523 Å according to [2]. The BTO single crystal belongs to the continuous solid
solution group of Bi1−xTexO(3+x)/2 [3]. It is presumed that subcell distorted of flu-
orite type with the side about 5.5 Å is a basis of this solid solution structure. The
unit-cell is formed by a multiplicity along cell axes 2x3x1 respectively. The temper-
ature studies of changing cell parameters and symmetry have not been carried out
earlier. Therefore the aim of this work is X-ray research of Bi2TeO5 single crystals
in a wide temperature range including the area of phase transition supposed.
The (100), (010) and (001) single crystal plates oriented and polished with the
size of 10x15x2 mm3 and the powder of the Bi2TeO5 single crystals grown were
used. The single crystal boules of bismuth tellurite were prepared as in the work [4]
from the melt by the Czochralski technique at the starting ratio of the Bi2O3 and
TeO2 components 47 and 53 mole % respectively. The sample X-ray patterns were
recorded with the DRON 2.0 difractometer (CoKα
-radiation filtered). For the high-
temperature measurements the UVD-2000 accessory was used. In table 1 the po-
sitions and the relative intensities of X-ray maxima from the BTO single crystal
powder are presented at room temperature. The difractograms of BTO single crys-
tal cuts show a=11.616 Å, b=16.451 Å and c=5.524 Å at room temperature and
systematic extinctions for oriented plates taking into account non-centrosymmetry
are stowed to the Abm2 space group.
c© K.V.Domoratsky, E.F.Dudnik, V.F.Katkov, L.Ya.Sadovskaya 591
K.V.Domoratsky et al.
Table 1. Data of X-ray maxima from the BTO single crystal powder at room
temperature.
N d, Å I/I0, % hkl N d, Å I/I0, % hkl
1 11.601 32 100 9 2.315 9 500
2 5.791 4 200 10 1.990 34 460,402
3 3.869 6 300 11 1.726 58 133
4 3.22 100 231 12 1.688 10 480
5 3.136 34 311 13 1.611 16 462
6 2.890 >100 400 14 1.108 14 971
7 2.753 14 002 15 0.910 6 176
8 2.659 4 160 16
0 100 200 300 400 500 600 700 800 900
5.50
5.55
5.60
5.65
5.70
cC
el
l p
ar
am
et
er
, A
t, 0C
11.6
11.7
a
16.5
17.0
b
(*)
o
760 800
11.74
11.76
Figure 1. The temperature dependence of BTO cell parameters (changing pa-
rameters at heating are shown as circles: hollow ones are low-temperature phase,
solid ones are high temperature phase; and changing at cooling are shown as
downward triangles: hollow ones are high-temperature phase and solid ones are
low-temperature phase).
592
X-ray investigations of Bi2TeO5 crystals
Table 2. The most inten-
sive maxima of the sur-
face deposit.
N d, Å I/I0, %
1 3.24 32
2 3.14 13
3 2.76 100
4 1.58 18.5
5 1.44 6.5
6 1.38 55
7 1.48 7.5
8 1.45 5
In figure 1 the temperature unit-cell parameter
changes of the bismuth tellurite single crystals are
showed. As it can be seen from the figure the pa-
rameters steadily increase with the temperature rise.
The thermal expansion coefficients over the range of
20–780 ◦C are close to each other for all directions:
αa ∼ 1.6 · 10−5 deg−1 (a-axis), αb ∼ 1.2 · 10−5 deg−1
(b-axis) and αc ∼ 1.5 · 10−5 deg−1 (c-axis). At 805 ◦C
parameter values increase step-wise. The largest change
occurs along b-axis (∆b is ∼ 0.36 Å or 2.3 %). For polar
axis ∆c is ∼ 0.064 Å (1 %). The smallest step is noticed
for the direction perpendicular to the cleavage surface
(∆a is ∼ 0.006 Å or 0.05 %). The anomalies observed
suggest that at 805 ◦C the phase transition takes place
in the solid phase (melt point ∼ 900 ◦C [5]). Over the
range 805–810 ◦C the co-existence of diffraction maxima corresponding to low- and
high-temperature phases (LP and HP respectively) is noticed and the fast intensity
redistribution is observed. The HP parameter values are adduced in figure 1 with
the LP indexes. The transition at cooling differ from the process occurring at heat-
ing by a diffusion. The LP nucleation appears at ∼ 750 ◦C. The transition to the
low-temperature phase is prolonged up to 700 ◦C. It should be noticed that at the
thermocycling both the situation of the parameter increasing step-wise at heating
and the phase transition shift and diffusion at cooling is reproduced. The character
of the cell parameter change enables us to consider the first-type phase transition
taking place in BTO at 805 ◦C. This PT temperature is somewhat higher than it
is given in the work [1]. Probably that is caused by somewhat different starting
component contents in the samples investigated.
At the durational high-temperature difractometer measurements of BTO single
crystals cuts, the material sublimation effect appears. That is reflected in the X-ray
patterns by the emerging of additional maxima which are revealed from the temper-
ature of ∼ 750 ◦C and which last at cooling to room temperature. The substance
formed is registered by sight as a yellowish-rose-tinted deposit. Moreover, while the
work face of the specimen has a rough surface the back face adjoining the platinum
dish practically stays undamaged. The values of the interfacial distances and relative
intensities of the most intensive maxima are presented in table 2.
All these lines can hardly be connected with the onset of some single composition
of the Bi2O3-TeO2 system. This fact allows us to consider the surface as the coating
multiphasity. As can be seen from table 2, two most intensive maxima, judging from
the d multiplicity, can be referred to the same composition. At cleaning the surface
coating by lapping, these maxima disappear. The chemical features of the bismuth
tellurite behaviour somewhat hamper the phase transition observing. However the
effects observed in figure 1 can only be explained by the structure changes, which
result from the 1-st type phase transition.
The data obtained confirm the DTA research data which demonstrate the endoef-
593
K.V.Domoratsky et al.
fect presence at heating in the corresponding temperature region. This also indicates
to the first-type phase transition.
Thus, high-temperature X-ray studies of the single crystal cuts confirmed the
phase transition in bismuth tellurite single crystals but that is the 1-st type transi-
tion.
References
1. Stefanovich S.Yu., Sadovskaya L.Ya., Antonenko A.M. Phase transition in bismuth
tellurite. // Sol. State Phys., 1991, vol. 37, No. 7, p. 2215–2217.
2. Mercurio D., Farissi M. El., Frit B., Goursat P. Etude structurale et densification d’un
noveaux materiau piezoelectrique Bi2TeO5. // Mater. Chem. and Phys., 1983, vol. 12,
No. 9, p. 467–476.
3. Mercurio D., Frit B., Harburn G., Parry B.H., Williams R.P., Tilley R.J.D. Diffraction
patterns from ordered intergrowth phases in the Bi2O3-TeO2 system. // Phys. Stat.
Sol. (a), 1988, vol. 108, p. 111–122.
4. Domoratsky K.V., Kudzin A.Yu., Sadovskaya L.Ya., Sokolyanskii G.Ch. Doping in-
fluence on the physical properties of Bi2TeO5 single crystals. // Ferroelectrics, 1998,
vol. 214, p. 191–197.
5. Földvary I., Peter A., Voszka R., Kappers L.A. Growth and properties of Bi2TeO5
single crystals. // J. Cryst. Growth, 1990, vol. 100, p. 75–77.
Рентгенівськi дослiдження фазового переходу у
монокристалах Bi2TeO5
К.В.Доморацький, О.Ф.Дуднiк, В.Ф.Катков,
Л.Я.Садовська
Днiпропетровський державний унiверситет,
320625 м. Днiпропетровськ, вул. Казакова, 20
Отримано 12 жовтня 1998 р.
Ця робота присвячена дослiдженню фазового переходу в моно-
кристалах телуриту вiсмуту методом високотемпературного рентге-
ноструктурного аналiзу. Виявленi стрибкоподiбнi змiни параметрiв
комiрки при 805 ◦С. Виходячи з отриманих даних, можна казати, що
у телуритi вiсмуту має мiсце фазовий перехiд 1-го роду.
Ключові слова: фазовий перехiд, телурит вiсмуту, рентген,
дифракцiйнi максимуми
PACS: 61.50.K
594
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