Low temperature synthesis route and structural characterization of (Bi0.5A0.5)(Sc0.5Nb0.5)O3 (A = K+ and Na+) perovskites

T. Wesley Surta, Alicia Manjón-Sanz, Eric Qian, T. Thao Tran, Michelle R. Dolgos

Index: 10.1039/C8QI00144H

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Abstract

Two new perovskites, (Bi0.5A0.5)(Sc0.5Nb0.5)O3 where A = K+ and Na+, have been made phase pure for the first time. The synthesis procedure that prevented the formation of pyrochlore impurities is described. B-site ordering in A = K+ is successfully achieved by prolonged heating. Combined Rietveld refinement on synchrotron X-ray diffraction and neutron diffraction data is used to determine the complex average structure of these materials. A = Na+ crystallizes in the tetragonal P4/mbm space group and has disordered a0a0c+ rotations of BO6 octahedra. A = K+ crystallizes in the cubic Pmm space group, but shows local A-site displacements in the [100] direction. Both materials are highly disordered but illustrate the potential of (A)NbO3-BiScO3 solid solutions as useful piezoelectrics or relaxors.