Crystal Structure of the Layered Perovskite-Like Srn(Nb,Ti)nO3n+2 Compounds. Part II. TEM Study of the Srn(Nb,Ti)nO3n+2

Published

October 16, 2008

Author(s)

Igor Levin, Leonid A. Bendersky, Terrell A. Vanderah

Abstract

Series of Srn(Nb,Ti)_nO_3n+2 structures with n=4,4.5,5,6 and 7 were studies by transmission electron microscopy. These structures are composed of inifite two-dimensional slabs of the distorted perovskite structure that are n' (Ti,Nb)O6 octahedra thick and extend parallel to the (110)p( p' refers to cubic perovskite) plane. The slabs are displaced with respect to each other with a 1/2[011]p translation vector. The structures with n=4,5,6 and 7 were shown to undergo commensurate->incommensurate phase transition on cooling at temperatures ranging from 150oC to 250oC. The n-5 incommensurate phase further transformed at T=180 to the monoclinic structure with the space group P112l/b. For n=4, 6 and 7 structures no lock-in transition was observed down to -170oC. For the compound with n=4.5 the transition from orthorhombic to monoclinic structure (P1121/b) occurred on cooling at T=390oC. All these transitions in Sr_n(Nb,Ti)nO_3n+2 compounds were attributed to the tilting of (Nb,Ti)O6 octahedra.

Citation

Acta Crystallographica Section B-Structural Science

Pub Type

Journals

Keywords

in-situ heating, incommensurate modulation, lattice imaging, layered structure, octahedra tilting, oxides, perovskite, phase transition

Citation

Levin, I. , Bendersky, L. and Vanderah, T. (2008), Crystal Structure of the Layered Perovskite-Like Sr_n(Nb,Ti)_nO_3n+2 Compounds. Part II. TEM Study of the Sr_n(Nb,Ti)_nO_3n+2, Acta Crystallographica Section B-Structural Science (Accessed April 26, 2024)