Structural study of FeP2 at high pressure.

The structural stability of marcasite-type FeP2 at high pressure has been studied by X-ray diffraction, Raman spectroscopy, and theoretical calculations. Experimental results show that no phase transitions happen up to 28 GPa at room temperature. The shortest axis of the marcasite-type FeP2 cell, the c-axis, is the most compressible, due to the softening of edge-shared octahedra along the c-axis. The linear pressure coefficients and Gruneisen parameters of four Raman modes are determined. Theoretical calculations further support the experimental results and indicate that FeP2 is still a semiconductor up to 35 GPa. [ABSTRACT FROM AUTHOR]