Rat-nan spectral characterization of existing phases in the ZrO2-Y2O3-Nb2O5 system

Abstract

Tetragonal zirconia polycrystals (TZPs) were prepared with additions of 5.31 mol% Y2O3 plus up to 5 mol% Nb:OS and their existing phases were investigated by Raman spectroscopy and X-ray diffraction, The present study reveals that Raman spectroscopy can identify the existing phases of cubic (c)-, tetragonal (t)-, monoclinic (m)-ZrO2, and Y-Nb ordered phase. The phase stability of t-ZrO2 may be governed by the competition between stable and transformable t-phase as a function of Nb2O5 content. Raman spectra of TZPs exhibit a broad and diffuse peak at around 770 cm(-1) in contrast to the c-. t- and m-phases due to local ordering. The local environment of Nb5+ in this system is maintained throughout Nb2O5 concentrations (0 < Nb2O5 less than or equal to 5 mol%), indicating that the 770 cm(-1) mode is likely to be related to the stable t-phase. (C) 2001 Elsevier Science Ltd and Techna S.r.l. All rights reserved.