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CRYSTAL STRUCTURE AND PROPERTIES OF NEW CADMIUMAND THALLIUM-CONTAINING
PEROVSKITES
Yu. Venevtsev, A. Kapyshev, V. Lebedev, V. Sal’Nikov, G. Zhdanov
To cite this version:
Yu. Venevtsev, A. Kapyshev, V. Lebedev, V. Sal’Nikov, G. Zhdanov. CRYSTAL STRUCTURE AND
PROPERTIES OF NEW CADMIUMAND THALLIUM-CONTAINING PEROVSKITES. Journal de
Physique Colloques, 1972, 33 (C2), pp.C2-241-C2-242. �10.1051/jphyscol:1972283�. �jpa-00215019�
JOURNAL DE PHYSIQUE Colloque C2, supplLment au no 4, Tome 33, Avril 1972, page C2-241
CRYSTAL STRUCTURE AND PROPERTIES OF NEW CADMIUM- AND THALLIUM-CONTAINING PEROVSKITES
Yu. N. VENEVTSEV, A. G. KAPYSHEV, V. M. LEBEDEV V. D. SAL'NIKOV and G. S. ZHDANOV
Karpov Institute of Physical Chemistry, Moscow, U. S. S. R.
Rksumk. - De nouveaux composts du type pervoskite ti base de cadmium et de thallium ont kt6 synthetises. Une etude aux rayons X et des mesures de propriktes diklectriques ont Bte rkalisees. I1 a kt6 possible de conclure qu'ils sont caractkrisables par leur polarisation spontanke.
Abstract. - New cadmium- and thallium-containing perovskites have been synthesized. A X-ray study and some dielectric measurements have been fulfilled. It has been concluded that a sponta- neously-polarized characterizes their.
A search and creation of new ferroelectric com- pounds is an important problem in the present time.
Investigations of Karpov Institute in this direction have led to a synthesis of some new Cd- and T1- containing perovskites, which are characterized an existence of the spontaneously-polarized state.
Cd-containing perovskites. - Our eartlier conclusion on high Curie point (w 950 0C) of cadmium tita- nate [I] stimulated a synthesis and research of new Cd-containing perovskites of complex composi- tions [2]-[4].
Table I contains X-ray data on earlier known perovskites (CdTiO, and CdSnO,) [5] and new perovskites. The last are formed as rule through the pyrochlore phase. Most of them as well as cadmium titanate have monoclinic subcells with the parameters : a = c # b ; bla > 1 and
fi
> 90°. ~ ( t ) and tg 6(t) have been investigated for ceramic samples Cd(Mnl/2Nbl/2)03(El), Cd(Mg1/9Nb2/3)03(E3) at 200 K H z and CdHfO, (-2, [6]), see figure 1. Grown single crystals of 3 perovskites have been used for the same aim [4].TABLE I Cd-containing perovskites
Compounds
-
CdTi03 [5]
CdSnO3 [5]
CdHfO3 [6]
Cd(Sci/zNbi/z)O3 Cd(Fel/~Nbl/z)O3
~d(~o:Tz~bi,2)03
cd(co:;3~b2/3)03
Cd(Mgi/3Nbz/3)03
c ~ ( M ~ ? & N ~ I I z ) o ~
Cd(Cr112Nbl12)Of
C ~ ( S ~ I I ~ T ~ I I Z ) O : * C d ( ~ e l / z ~ a l / z ) ~ T *
Parameters of a monoclinic subcell
a = c (4) b (A) b/a fi
- - - - 3.791 3.807 1.004 91° 10' 3.933 3.934 1.0002 900 19' 3.942 3.982 1.001 91° 36' 3.872 3.907 1.009 91°27' 3.826 3.848 1.006 910 20' 3.874 3.904 1.0077 91'37' 3.862 3.900 1.010 91° 32' 3.840 3.876 1.007 91° 25' 3.870 3.916 1.012 91°27' 3.903 3.870 0.991 90° 39' 3.873 3.900 1.009 91°29' 3.825 3.848 1.006 91° 22' (*) Single crystals contain about 1 weight % Na as an impurity (**) Samples contain the second pyrochlore phase.
The results of the present study, of our earlier data on CdTiO, [l] and of the recently published data on CdHfO, [6] allowed to conclude that these new cadmium-containing perovskites are either antiferro- electrics or ferrielectrics and possess the higher Curie points as compared with the corresponding lead- containing perovskites (see Table I1 and [3], [4]).
Article published online by EDP Sciences and available at http://dx.doi.org/10.1051/jphyscol:1972283
YU. N . VENEVTSEV AND COLL.
Curie temperatures Pb-
and Cd-containing perovskites A(B: B:'-~) O,
(*) Single crystals contain about 1 weight
%
Na as an impurity [4].(**) data of Rostovon-Don University [6].
(*
*
*) Nuclear gamma-resonance data [7].TI1+-containing perovskites. - All known lead- containing perovskites and, evidently, all bismuth- containing perovskites (BiFeO,, Kl12Bill,)Ti03 and other) have anomalous dielectric properties. In this connection it is important to synthetize and study TI1+-containing perovskites [8], since TI1+ has an electron configuration similar to that of the Pb2+- and ~ i ~ + - c a t i o n s . On the other hand TI1+-cation has a large ionic radius (1.49
A)
and therefore it will be ((free )) B-cations in octahedra of above mentioned perovskites. For example Goldshmidt tolerance factor t for a possible perovskite T11f(Til~,Wl12)03 equals 1.07. Consequently (( geometrical looseness a of unit cells of such perovskites can be an other factor, favouring the origination of the spontaneously-polari- zed state.More than 20 new perovskites of the composition T I ' + ( B ~ B:'X) O, (with B" = W6+, Mo6+ and B1 = B'+, B2+, B3+, B4+) have been synthesized [9],
[lo]. X-ray data on some of them and a known perov- skite TIJO, [5] are given in table 111. At room tempera- ture all new perovskites have rhombohedra1 unit cells.
A study of crystal structure and dielectric properties of solid solutions in systems PbBO, (I)-TIZrl,,Wl~,03 (11), where B = Zr (Fig. 2) or Ti, showed that I1 is in
TABLE I11
Some TI1+ -containing perovskites
Compounds a M
the spontaneously-polarized state and its Curie point about 310 OC [lo].
An absence of superstructure lines on X-ray powder patterns of I1 and other TI-containing perovskites owing to possible antiparallel displacements of che- mically identical ions allows to conclude that these perovskites are ferroelectrics [lo].
It is, however, neccessary to continue investigation for a detailed study of a character of dielectric pro- perties (ferri- or antiferroelectric) of Cd-containing perovskites and to obtain either first or more definite data on Curie points and other phase transitions of all new perovskites.
We thank d-r Yu. Ja. Tomashpolsky for his advices and help.
References [I] RODICHEVA (Ye. N.), LEBEDEV (V. M.), SHAPIRO (Z. I.),
FEDULOV (S. A.) and VENEVTSEV (Yu. N.), Pro- ceedings of the Jnternational Meeting on Ferro- electricity (Pragiic), 1966, 1, 370.
[2] VENEVTSEV (Yu. N.), KAPYSHEV (A. G.), SHVOR-
NEVA (L. I.), TOMASHPOLSKY (Yu. Ja.), VIS- cow (A. S.), ZUBOVA (Ye. V.), IVANOVA (V. V.), DEMUROV (D. G.), DZHMUKADZE (D. F.), SAL'NIKOV (V. D.) and ZHDANOV (G. S.), J . Phys.
Soc. Japan, 1970, 28, Supplkment, 139.
[3] DEMUROV (D. G . ) , VENEVTSEV (Yu. N.), K~ist~llo- graphiya, 1971, 16, 168.
[4] SAL'NIKOV (V. D.), VENEVTSEV (Yu. N.), ZZV. Akad.
Nauk,S. S. S. R.,Ser.fiz., 1971,35,1838.
[S] GALASSO (F. S.), Structure, Properties and Preparation of Perovskite-Type Compounds. Pergamon Press, Oxford, 1969.
[6] AVER'YANOVA (A. N.), BELYAEV (I. N.), GOL'T- sov (Yu. I.), SOLOY'EV (A. A.), SPINKO (R. I.) and PROKOPALO (0. I.), Fiz. Tverdogo Tela, 1968, 10, 341 1 .
[71 VENEVTSEV (Yu. N.), IVANOVA (V. V.), GOLOV-
NIN (V. A.), KASHLINSKII (A. I.), KOZLOVA (L. A.) and KUZ'MIN (R. N.), ZZV. Akad. Nauk S. S. S. R., Ser. jiz., 1971, 35, 1829.
181 SMOLENSKII (G. A.). ISUPOV (V. A.). AGRANOV-
- -
SKAYA (A. I.), KRAINIK (N: N.), ~ i z . Tverdogo Tela, 1960, 2, 2982.
[9] KAPYSHEV (A. G.), VENEVTSEV (Yu. N.), Electronnaya tekhnika, Ser. Materialy (neorganicheskie dielec- triki) 1964, N 4 (20), 58.
rlOl KAPYSHEV (A. G.). VENEVTSEV (Yu. N.). GAIDU-
- -
KOVA
