  The high-pressure phase stability of the metastable tetragonal zirconia is
still under debate. The transition dynamics of shocked Y2O3 (3 mol%) stabilized
tetragonal zirconia ceramics under laser-shock compression has been directly
studied using nanosecond time-resolved X-ray diffraction. The martensitic phase
transformation to the monoclinic phase, which is the stable phase for pure
zirconia at ambient pressure and room temperature, has been observed during
compression at 5 GPa within 20 ns without any intermediates. This monoclinic
phase reverts back to the tetragonal phase during pressure release. The results
imply that the stabilization effect due to addition of Y2O3 is negated by the
shear stress under compression.
