HIGH-PRESSURE X-RAY AND RAMAN-STUDY OF ZNSE

ZnSe has been studied in a diamond anvil cell by energy dispersive X-r ay diffraction with a synchrotron source to 120 GPa and by Raman spect roscopy to 11 GPa. An apparent anomaly in the equation of state, and d iscontinuity of the TO and LO Raman frequencies vs pressure was observ ed in the zinc blende phase at 5 GPa. A small structural distortion wa s observed in the rock salt phase between 12 and 47 GPa. The rock salt phase transformed to a simple hexagonal type structure at 55 +/- 8 GP a.