Compression behavior of CdS and BP up to 68 GPa

High-pressure in situ x-ray diffraction study on CdS and BP was performed using a diamond anvil cell up to 68 GPa at room temperature. The rocksalt structure type CdS was found to transform to a new high-pressure polymorph at about 56 GPa. X-ray diffraction pattern of the new high-pressure polymorph was successfully indexed by the lowest temperature KCN structure type with the distorted rocksalt structure. Volume change accompanied with the transformation was calculated to be about 0.8%. This small volume change may be responsible to the undetectable change in refractive index of CdS at the transformation. No phase transformation was observed on BP: the zincblende structure is stable up to 68 GPa.