High-pressure studies of MSb3 (M = Fe, Co) at quasi-hydrostatic conditions

TL;DR

This study compares the high-pressure compressibility of CoSb3 and FeSb3 skutterudites, providing the first equation of state for FeSb3 and observing a potential structural transition in CoSb3 at high pressures.

Contribution

First direct measurement of FeSb3's equation of state and comparative analysis of both skutterudites under high pressure.

Findings

Bulk moduli: 95 GPa for CoSb3, 86 GPa for FeSb3

First equation of state for FeSb3

Observed structural anomaly in CoSb3 at 34.4-39.6 GPa

Abstract

We present a comparative study of the unfilled CoSb3 and FeSb3 skutterudites and report on their compressibility studied by high-pressure synchrotron X-ray diffraction. The equation of state for FeSb3 was received for the first time. The third order Birch- Murnaghan isothermal equations of state were fitted to the experimental data in the pressure ranges atm-34 GPa for CoSb3 and atm-14 GPa for FeSb3. Bulk moduli of 95(5) GPa and 86(4) GPa have been obtained for CoSb3 and FeSb3, respectively. The bulk modulus of FeSb3 is in a contrast by about 30% with literature value obtained indirectly. Anomaly was observed in the diffraction pattern of CoSb3 at the pressures 34.4-39.6 GPa which is most probably reasoned by structure transition.