Cooperative behavior of Zn cations in Bi-based perovskites: A comparison of (Bi,Sr)2ZnNbO6 and (Bi,Sr)2MgNbO6
- ORNL
We investigated the polar behavior of the double perovskite (Bi,Sr)2MgNbO6 using first-principles density-functional theory calculations. We find that the magnitude (75 C/cm2) and direction (along [111]) of the polarization are comparable to our previous results for the A-site size difference (Bi,Sr)2ZnNbO6 and (Bi,Pb)2ZnNbO6 systems. However, comparisons with the (Bi,Sr)2ZnNbO6 compound indicate that the presence of Zn modestly enhances the off-centering of the Sr and Nb cations as well as the Born effective charges of both Bi and Nb. Analogous to the corresponding Pb- based perovskites, Pb(Mg1/3Nb2/3)O3 and Pb(Zn1/3Nb2/3)O3, we demonstrate that the difference in the experimentally observed critical temperatures are related to the differences in polarization between the two materials. A local dipole analysis indicates that the most significant contribution arises from the enhanced cooperative couplings with the larger Zn displacements.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 1016049
- Journal Information:
- Physical Review B, Vol. 83, Issue 11; ISSN 1098--0121
- Country of Publication:
- United States
- Language:
- English
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