Determination of tetragonal-cubic phase boundary of Zr(1-x)R(x)O(2-x/2) (R=Nd,Sm,Y,Er and Yb) by Raman scattering

Existing phases of are-melted ZrO2-Xmol%RO(1.5) specimens were investigated mainly by Raman spectroscopy, which is sensitive to the phase transition induced by the oxygen displacements (0 less than or equal to X less than or equal to 24) R = Nd, Sm, Y, Er and Yb). The tetragonal and monoclinic phases coexisted at X = 2 and 4 for R = Nd, Y, Er and Yb, and at X = 2 for R = Sm. Tetragonal single phase is obtained in the specimens with higher contents. The axial ratio cia decreases with an increase of RO(1.5) content and becomes unity at 14 or 16mol% RO(1.5) content. The Raman peak intensity at about 470 cm(-1), which is characteristic of the tetragonal phase, decreases with an increase of RO(1.5) content. The cubic-tetragonal phase boundary determined by Raman scattering is located at about X = 18 - 19 mol% regardless of dopant species R. A tetragonal phase whose axial ratio cia is unity appears at about X = 16 mol%. The compositional locations of the phase boundaries are almost independent of the dopant species R.