ePubs

The open archive for STFC research publications

Full Record Details

Persistent URL http://purl.org/net/epubs/work/54374102
Record Status Checked
Record Id 54374102
Title Structure and thermal expansion of end-member olivines I: Crystal and magnetic structure, thermal expansion, and spontaneous magnetostriction of synthetic fayalite, Fe2SiO4, determined by high-resolution neutron powder diffraction
Contributors
Abstract The lattice parameters and the crystal and magnetic structures of Fe2SiO4 have been determined from 10 K to 1453 K by high-resolution time-of-flight neutron powder diffraction. Fe2SiO4 undergoes two antiferromagnetic phase transformations on cooling from room temperature: the first, at 65.4 K, is to a collinear antiferromagnet with moments on two symmetry independent Fe ions; the second transition, at ~23 K, is to a structure in which the moments on one of the sets of Fe ions (those on the “M1 site”) become canted. The magnetic unit cell is identical to the crystallographic (chemical) unit cell and the space group remains Pbnm throughout. The magnetic structures have been refined and the results found to be in good agreement with previous studies, but we have determined the spontaneous magnetostrictive strains, which have not previously been reported. In the paramagnetic phase of Fe2SiO4, at temperatures of 70 K and above, we find that the temperature dependence of the linear thermal expansion coefficient of the b axis takes an unusual form. In contrast to the behaviour of the expansion coefficients of the unit-cell volume and of the a and c axes, which show the expected reduction in magnitude below ~300 K, that of the b axis remains almost constant between about 70 K and 1000 K.
Organisation ISIS , ISIS-HRPD , STFC
Keywords
Funding Information NERC, Standard Grant (NE/S007229/1 ); NERC, Standard Grant (NE/T006617/1); ISIS Neutron and Muon Source, Direct Access Beamtime (RB1910186)
Related Research Object(s): 10.5286/ISIS.E.RB1910186
Licence Information: Creative Commons Attribution 4.0 International (CC BY 4.0)
Language English (EN)
Type Details URI(s) Local file(s) Year
Journal Article Miner Mag (2023): 1-42. doi:10.1180/mgm.2023.66 2023