Structural Behavior and Raman Spectra of Perovskite-Like Solid Solutions (1-x)LaMg0.5Ti0.5O3-xLa2/3TiO^d3

Published

June 14, 2005

Author(s)

Igor Levin, Terrell A. Vanderah, T Amos, James E. Maslar

Abstract

Structural behavior and phase transitions in the A-cation deficient perovskite-like solid solutions (1-x)LaMg0.5Ti0.5O3-xLa2/3TiO3 (0=x=0.5) were studied using variable-temperature transmission electron microscopy (TEM) and X-ray powder diffraction combined with ambient temperature neutron powder diffraction measurements. These solid solutions feature a series of octahedral-tilting phase transitions and a B-site Mg/Ti order-disorder phase transition; the temperatures of these transitions decreased with increasing x. Additionally, short-range ordering of A-site vacancies was detected for x>0.40 using high-resolution TEM. A phase diagram summarizing ordering and displacive phase transitions was determined from variable-temperature diffraction and imaging experiments. Among the tilting transitions, a relatively uncommon first-order phase transition between structures exhibiting orthorhombic (a+b-b- and a0b-c-) and rhombohedral (a-a-a-) tilt systems was observed; the rhombohedral tilt was stabilized at room temperature for x=0.50. Raman spectra of the solid solutions revealed anomalous asymmetric broadening of certain peaks associated with B-site ordering. This broadening, which occurred even for the samples exhibiting significant long-range Mg/Ti order and large anti-phase ordered domains, was attributed to phonon confinement effects caused by strong heterogeneity of the B-site order parameter within each anti-phase domain.

Citation

Chemistry of Materials

Volume

17

Issue

12

Pub Type

Journals

Download Paper

Local Download

Keywords

crystal structures, perovskites, phase transitions, Raman spectra

Citation

Levin, I. , Vanderah, T. , Amos, T. and Maslar, J. (2005), Structural Behavior and Raman Spectra of Perovskite-Like Solid Solutions (1-x)LaMg_0.5Ti_0.5O_3-xLa_2/3TiO^d3, Chemistry of Materials, [online], https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=850851 (Accessed April 25, 2024)