High-pressure X-ray diffraction study of tungsten diselenide

Synchrotron X-ray diffraction was used in conjunction with a diamond anvil cell to investigate the properties of a tungsten diselenide (WSe2) sample to 35.8 GPa at room temperature. By fitting the pressure–volume data to the third-order Birch–Murnaghan equation of state, the bulk modulus, K0T, of WSe2 was determined to be 72±1 GPa with its pressure derivative, K0T′, being 4.1±0.1. It was also found that the c-direction of the hexagonal structure is significantly more compressible than the a-direction. No phase transformation was clearly observed in the pressure range of our measurements.