Cubic-tetragonal phase change of yttria-doped hafnia solid solution: high-resolution X-ray diffraction and Raman scattering

High-resolution synchrotron X-ray powder diffraction and Raman scattering have demonstrated the existence of tetragonal yttria-doped hafnia solid solution with an axial ratio, c(f)/a(f), of unity, but having displacements along the cf(-) axis from the ideal fluorite position in the oxygen sublattice. The values of c(f)/a(f) ratio in HfO2-X mol%YO1.5 samples (X = 13, 14, and 16) are estimated to be unity with the precision of +/-0.00003 from the estimated standard deviation of the peak position and less than +/-0.001 from the full-width at the half-maximum of the 400(f) reflection peak. However, the Raman spectra of the samples of X = 13, 14, and 16 clearly demonstrate the tetragonal phase. (C) 2001 Elsevier Science B.V. All rights reserved.