Knowledge Bank

Powder samples must be employed when a crystalline materials under study is not available as a thin film or a large single crystal with oriented optically polished surfaces for infrared transmission and reflection measurements. Zirconium dioxide powders which occur in the cubic, tetragonal and monoclinic phases have been investigated to isolate the infrared frequencies characteristic of the various polymorphs. It is shown that the reflection spectrum of a bulk sample of stabilized cubic zirconia is a good first approximation to its powder transmission spectrum. This provides the basis for interpreting the other powder spectra in terms of infrared dispersion theory. Preliminary Raman spectra are presented, and the experimental vibrational spectra are compared with the activity predicted by factor group theory. The infrared spectra of monoclinic zirconias are shown to be very sensitive to lattice strain.