Pressure-induced phase transitions of ZnSe under different pressure environments

The structural, vibrational and electronic properties of ZnSe under different pressure environments up to ∼40.0 GPa were investigated using a diamond anvil cell in conjunction with ac impedance spectroscopy, Raman spectroscopy and high–resolution transmission electron microscopy. Under the non–hydrostatic condition, ZnSe exhibited a structural phase transition from a zinc–blende to a cinnabar structure at ∼4.9 GPa, indicated by the obvious splitting of the transverse optical mode in the Raman spectra and a noticeable variation in the slope of the electrical conductivity. With increasing pressure, metallization appeared at ∼12.5 GPa, which was characterized by the high–pressure Raman spectroscopy and temperature–dependent electrical conductivity results. When the pressure was increased up to ∼30.0 GPa, another phase transition was identified by the appearance of a new peak in the Raman spectra. Compared to the non–hydrostatic condition, a roughly 2.0 GPa delay of transition pressure for ZnSe was observed a...