A SEARCH FOR SOLID-SOLUTIONS IN THE ALPHA-AL2O3-M-ZRO2 SYSTEM BY XRD

A search for solid solutions in the system alpha-Al2O3-m-ZrO2 was unde rtaken using precise X-ray powder diffraction measurements. The sample s covering the whole concentration range were prepared using chemical coprecipitation and ceramic sintering. Maximum heating temperature was 1100 degrees C. Except for the very ends of the concentration range, the samples contained two phases, structurally closely related to m-Zr O2 (monoclinic) and alpha-Al2O3, respectively. Most samples also conta ined a small fraction of t-ZrO2 (tetragonal), which was estimated to b e less than 1 mol%. It was found that the solubility of alpha-Al2O3 in m-ZrO2 was small, amounting to 0.7 +/- 0.3 mol%, while the solubility of m-ZrO2 in alpha-Al2O3 was negligible. These solid solubility limit s were discussed in terms of ionic radii of Al3+ and Zr4+ cations.