ABSTRACT
Zirconia-based ceramics represent a class of unique materials in which stress-induced phase transitions determine most of their practical applications. The most important analytical technique for near-surface transformations in zirconia is Raman microspectroscopy. The martensitic thermodynamically reversible transformation of pure zirconia is characterized by a diffusion-less shear process close to the acoustic velocity, combined with hysteresis on heating and cooling. Different types of zirconia materials with distinctly different microstructures are manufactured. Zirconia has been added to a variety of other oxide matrices but the first system to be developed was zirconia-toughened alumina. High-pressure investigations are a simple technique with which to examine the behaviour of zirconia under external stresses. The chapter discusses the Raman spectra of the most important phases of zirconia and the effects of temperature, pressure and grain size on the band positions. The main advantage of Raman spectroscopy is its simple set-up, because a surface can be examined without special sample preparation.
