Abstract
The VF3-type compounds MF3 with M = Fe and Ga have been studied by high-pressure energy-dispersive X-ray diffraction. The compression mechanism was found to be highly anisotropic for both compounds, with the c-axis showing little pressure dependence. The volume reduction is mainly achieved through coupled rotations of the MF6 octahedra around the c-axis, which reduces the length of the a-axis. The compression mechanism of both compounds is reasonably well described in terms of deformation of an 8/3/c2 sphere-packing model up to the pressures where the fluorine atoms become hexagonally close-packed. It is proposed that both compounds enter a phase with the fluorine atom arranged in a super-dense sphere packing at higher pressures. The zero pressure bulk modulus of FeF3 and GaF3 was determined as 12(2) and 37(3)GPa, respectively, and a scaling relation between the zero pressure bulk modulus and unit cell volumes was found for TiF 3, CrF3, FeF3 and GaF3.
| Original language | English |
|---|---|
| Journal | High Pressure Research |
| Volume | 30 |
| Issue number | 4 |
| Pages (from-to) | 634-642 |
| Number of pages | 8 |
| ISSN | 0895-7959 |
| DOIs | |
| Publication status | Published - Dec 2010 |