Quantitative analysis of polymorphic mixes of zirconia by X-ray diffraction

Nonlinear calibration curves of weight fraction vs integrated intensity ratio arc obtained for polymorphic mixtures of ZrO2 by means of powder X-ray diffraction. The (C + M) and (T + M) ZrO2 systems are analyzed using the {111} reflections. Intensity ratios in mixtures prepared with an ultrafine m-ZrO2 powder agree well with theoretical values. The observed nonlinearity of the intensity-concentration curve is explicable from the differences in reflecting power of corresponding reflections in the three polymorphs. Considerable deviations from theoretical intensity ratios are observed in mixtures prepared with coarser commercially available m-ZrO2 powders. This effect is attributed to an anomalously high absorption behavior of those monoclinic materials and can be suppressed by quenching in liquid nitrogen, which is believed to cause the particles to shatter. The (C + T) ZrO2 system is analyzed using the {200} reflections rather than the more usual high-angle reflections and the derived nonlinear calibration curve agrees well with theoretical prediction. In the ternary system (C + T + M) ZrO2 the presence of tetragonal phase can be confirmed by microphotometric tracing of the {111} and {200} reflection profiles on Guinier photographs, but in this case a quantitative analysis would be difficult.