High-pressure structural behaviour of Cu0.5Fe0.5Cr2S4: An experimental and theoretical study

The structural behaviour of Cu0.5Fe0.5Cr2S4 has been studied experimentally and theoretically at pressures up to 44 GPa. The experiments are supported by density functional calculations using the full-potential linear muffin-tin orbital method for investigating ground state properties and high-pressure behaviour. We report here the first experimental and theoretical determinations of the bulk modulus: B0 = 106(2) GPa and B0′ = 4.0 (experimental), and B0 = 96 GPa and B0′ = 3.9 (calculated). Moreover, a pressure-induced structural and electronic phase transformation occurs at 14.5 GPa accompanied by a volume collapse of about 6%. Tentatively, the high-pressure phase is assigned the defect NiAs structure of Cr3S4 type with space group I2/m (12). The mechanism of the phase transition is explained by a Jahn-Teller type distortion, associated with geometrical frustration and magnetic spin changes.