0000000000017413
AUTHOR
P. Dumas
Investigation of lattice dynamical and dielectric properties of MgO under high pressure by means of mid- and far-infrared spectroscopy.
We investigate the lattice dynamical and dielectric properties of MgO single crystals and powders by measurements in the mid- and far-infrared frequency region under high pressures, ranging up to 21.7 GPa. The shift of the restrahlen region is used to determine the pressure dependence of the transverse and longitudinal optical modes. The analysis of the refractive index in the mid- and far-infrared region allowed us to obtain the pressure behavior of the static and electronic dielectric constants. The transverse effective charge slowly decreases under high pressure, reflecting the stability of MgO. As a consequence, the pressure dependence of the static and electronic dielectric constants i…
High-pressure study of the infrared active modes in wurtzite and rocksalt ZnO
International audience; We present a high-pressure study of ZnO carried out in the mid- to far-infrared frequency domain with the aim of characterizing the optic modes of wurtzite and rocksalt ZnO. We obtained the pressure coefficients of the E1(TO), E1(LO), A1(TO), and A1(LO) modes of the low-pressure wurtzite phase and compare them with previous Raman measurements. The optical modes of the high-pressure rocksalt phase are infrared active, so we were able to determine their wave numbers and pressure dependencies. In the wurtzite phase, high pressure induces a slight decrease in both longitudinal and transverse effective charges. The decrease is more pronounced in the rocksalt phase.