ChemInform Abstract: (A0.52+BI0.5)(B0.52+NB0.5)O3 COMPOUNDS

Abstract

Durch Brennen von Mischungen von Oxiden oder Carbonaten bei 1 170 K und dann bei 1420 bis 1620 K werden die im Titel genannten Verbindungen (mit A = Sr, Ba ; B = Mg, Zn) dargestellt.

Polar behavior of double perovskite (Bi,Pb)ZnNbO6 and (Bi,Sr)ZnNbO6: Density functional calculations

“…As mentioned, (Bi 0.5 Sr 0.5 )(Zn 0.5 Nb 0.5 )O 3 was synthesized by Kosyachenko and co-workers. 29 They reported a weakly tetragonal structure with lattice parameters a=b=4.002, and c=4.015 Å (c/a=1.003) at 293 K. These values are ∼ 0.9 % larger than our calculated LDA lattice parameter. This size of underestimation is typical of LDA errors.…”

“…Related to this there is an experimental report of the synthesis and some physical properties of perovskite (Bi 0.5 Sr 0.5 )(Mg 0.5 Nb 0.5 )O 3 , (Bi 0.5 Ba 0.5 )(Mg 0.5 Nb 0.5 )O 3 , (Bi 0.5 Sr 0.5 )(Zn 0.5 Nb 0.5 )O 3 , (Bi 0.5 Ba 0.5 )(Zn 0.5 Nb 0.5 )O 3 , and the solid solution of (Bi 0.5 Ba 0.5 )(Zn 0.5 Nb 0.5 )O 3 with PT and (Bi 0.5 Sr 0.5 )(Mg 0.5 Nb 0.5 )O 3 with SrTiO 3 . 28,29 The compound (Bi 0.5 Sr 0.5 )(Mg 0.5 Nb 0.5 )O 3 was reported to be ferroelectric based on the observation of a hysteresis loop below 103 K. All four compounds were reported to show phase transitions above room temperature and relatively high dielectric constants. They also show substantial microwave loss, which may indicate ferroelectricity.…”

Cooperative behavior of Zn cations in Bi-based perovskites: A comparison of (Bi,Sr)2ZnNbO6and (Bi,Sr)Takagi1, Cooper2, Singh3 2011Phys. Rev. B7080View full textAdd to dashboardCite

“…The calculated LDA lattice parameter of 3.97Å was found to be in good agreement with the room-temperature experimental value of 4.001Å. 18 The small difference of ∼1% with respect to the experimental value is typical of LDA calculations of oxide ferroelectrics and is a result of the LDA volume errors. We confirmed that our results are robust against the LDA volume error, as identical displacement patterns were obtained at the experimental volume.…”

“…The lowest energy structure was found to have a c/a = 1.000, corresponding to x-ray phase analysis results, where inappreciable distortions were observed. 18 Over the range considered (0.94 < c/a < 1.06), all cation off-centering remained essentially along the [111] direction, implying strong stability of the rhombohedral ferroelectric state.…”

“…(Note: BSMN and BSZN were previously experimentally determined to be ferroelectric, with the relatively high phase transition temperatures of 803 and 923 K, respectively. 17,18 ) Using an analysis of the contribution of the local dipole moment interactions to the transition temperature, we show that it is the coupling between Zn 2+ and other cations that promotes the higher transition temperature of the BSZN compound, thus emphasizing the cooperative nature of Zn off-centering within these materials. Hence, Zn plays a similar role in these Bi-based materials as in Pb-based piezoelectrics.…”