In situ x-ray diffraction and Raman spectroscopy have been carried out to pressures of 93.6 and 63.2 GPa, respectively, to explore the pressure-induced phase transformation of CoFe2O4 spinel. CoFe 2O4 adopts a distorted tetragonal spinel structure at one atmosphere. At a pressure of ∼32.5 GPa, both x-ray diffraction and Raman spectroscopy indicate that CoFe2O4 transforms to the orthorhombic CaFe2O4 structure, which remains stable to at least 93.6 GPa. The bulk modulus (K0) of the tetragonal and the high-pressure polymorphs were calculated to be 94(12) and 145(16) GPa, respectively, with K′ ≡ 4. Upon release of pressure the orthorhombic phase persists and appears to be structurally metastable. At zero pressure, laser induced heating leads to a significant transformation back to the tetragonal phase. The high-pressure orthorhombic phase at one atmosphere is 14.7% denser than the tetragonal phase.
|Original language||English (US)|
|Number of pages||6|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|State||Published - Sep 2003|
ASJC Scopus subject areas
- Condensed Matter Physics