Raman spectra of tetragonal zirconia: powder to zircaloy oxide frequency shift

The shifts of the two main characteristic Raman active bands of t-ZrO2 in o xide films developed on zirconium alloy relatively to their position in nan opowder (267, 456 cm(-1)) are discussed. The origin of the shifts is analyz ed within the lattice dynamical treatment according to which neither hydros tatic compression nor biaxial one can be responsible for this shift. It is put in evidence that only an abnormal high value of the internal tetragonal ity (Deltaz = L-z/c) can provide this effect. Additionally, the symmetry as signment of the two bands are determined which, in particular, argues for t he identification of the band near 267 cm(-1) as a totally symmetric A(1g) soft mode. (C) 2001 Elsevier Science B.V. All rights reserved.