The open archive for STFC research publications

Full Record Details

Persistent URL http://purl.org/net/epubs/work/48580700
Record Status Checked
Record Id 48580700
Title Structural phase transitions in the geometric ferroelectric LaTaO4
Abstract The recent report of an intermediate incommensurately modulated orthorhombic phase in LaTaO4 has prompted a re-examination of the phase transition sequence in LaTaO4 as a function of temperature. With falling temperature, the sequence of phases examined is (orthorhombic) Cmc21(C)↔Cmc21(IC)↔(monoclinic)P21/c, with C and IC denoting commensurate and incommensurate phases, respectively. The orthorhombic to monoclinic transition, Tm−o, is a first order reconstructive transition occurring at 440 K and TIC−C is a first-order displacive transition occurring at 500–530 K. Strain and elasticity data confirm a first-order transition between the basic and modulated Cmc21 phases, with similarities to the isostructural fluoride BaMnF4. A Raman spectroscopic study of the LaTaO4 phase transition indicates that the IC-C phase transition is driven by a soft zone-boundary phonon (unstable) of the commensurate orthorhombic (Cmc21) phase. The soft phonon is found to appear (underdamped) above 443 K and vanishes (overdamped) around 528 K. A large supercell of the monoclinic phase below Tm−o is proposed based on the Raman spectroscopic results.
Organisation ISIS , ISIS-HRPD , STFC
Funding Information EPSRC (EP/N509759/1); EPSRC (EP/P024637/1); EPSRC (EP/P024904/1); EPSRC (EP/I036079/1); DOD (FA9550-20-1-0064); NERC (NE/B505738/1); NERC (NE/F017081/1)
Related Research Object(s): 10.5286/ISIS.E.98019521
Licence Information:
Language English (EN)
Type Details URI(s) Local file(s) Year
Journal Article Phys Rev B 103, no. 1 (2021): 014119. doi:10.1103/PhysRevB.103.014119 2021