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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
Contributors
GW Howieson
,
KK Mishra
,
AS Gibbs (STFC Rutherford Appleton Lab.)
,
RS Katiyar
,
JF Scott
,
FD Morrison
,
M Carpenter
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
Keywords
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
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