Pressure-Induced Phase Transitions in InAs Studied by Angular-Dispersive X-ray Diffraction and Raman Spectroscopy

Pressure-induced phase transitions in indium arsenide (In As) at ambient temperature were investigated by using angular-dispersive X-ray diffraction (ADXRD) and Raman scattering under high pressure up to around 9.8(1) and 9.9(2) GPa, respectively, with a 4:1 (in volume ratio) methanol-ethanol mixture as the pressure transmitting medium (PTM). In situ ADXRD measurements revealed that In As starts to transform from zinc blende (ZB) structure to rock-salt (RS) phase at 6.7(1) GPa, consistent with most previously reported studies. The phase transition proceeds steadily over a wide range of pressures and reaches completion at the highest applied pressure of 9.8 GPa with significant metallization, as suggested by the disappearance of Raman modes. In contrast to previous studies, our data did not show evidence of structural transition to Cnncm phase, presumably due to the different PTMs used and/or insufficient pressure applied. The order of appearance of the major diffraction peaks of RS phase In As with increasing pressure and intensity are explained by the binding energy density of the corresponding plane families. The zero-pressure isothermal bulk moduli (B-0) and its first-pressure derivatives (B-0') for the ZB In As are 64(4) GPa and 3.8(2), respectively. The intensity of both the LO and TO phonon modes of ZB phase In As exhibits an abrupt decrease at 7.7(1) GPa, where equal weight fractions of ZB and RS phases are identified, suggesting the metallic nature of the RS phase.