Raman spectrum of zirconia-hafnia mixed crystals

Abstract

Monoclinic crystals of ZrxHf1−xO2 were grown by heating the layered structures ZrxHf1−xS2 in a pure oxygen atmosphere at 800 °C for 2 h (x=0, 0.1, 0.25, 0.5, 0.75, 0.9, and 1.0). Their Raman spectra were recorded at 15 and 300 K. The 18 modes predicted by group theory were identified in ZrO2 and their evolution with x was determined. At 15 K, seven phonons show distinct two-mode behavior, while others are characterized by discontinuities, either at x=0.6 or x=0.3. This latter observation is reminiscent of percolation-type phenomena.