Shift in low-frequency vibrational spectra measured in-situ at 600 °C by Raman spectroscopy of zirconia developed on pure zirconium and Zr–1%Nb alloy

Abstract

In this study displacement of monoclinic bands of zirconia were investigated in the function of oxidation time using the Raman spectroscopy technique. Oxidations were performed on pure zirconium and zirconium alloy in-situ at 600 °C for 6 h. Analysis of the absolute intensities as well as the positions of the characteristic for monoclinic and tetragonal phase Raman bands were performed. Reported results has highlighted that monoclinic phase of zirconia undergoes a continuous band displacement, individual for each Raman mode. Recorded shift of low frequency vibrational spectra of monoclinic phase was employed to study stress developed in zirconia during high temperature oxidation – herein called as growing stress. In addition, based on the Raman band intensity we discuss observed transition of the metastable tetragonal phase to stable monoclinic phase. Reported results, for the first time showed that studied metals (pure zirconium and its alloy) behave similarly in terms of band shift. However the resulting value of growing stress associated to the band displacement is slightly different in regards of individual band and studied sample.