Synthesis and Characterization of Oxynitrides in the ZrO 2-Rich Part of the Systems Ca-Zr-O-N and Mg-Zr-O-N
Abstract
Oxynitrides in the ZrO2-rich part of the systems Ca-Zr-O-N and Mg-Zr-O-N have been prepared by nitridation of the corresponding oxides in nitrogen atmosphere at temperatures between 1400 and 2000°C. A thermodynamic model of the nitridation is presented. The crystal structures of the resulting oxynitride phases are derived from the fluorite-type structure of the cubic high temperature phase of ZrO2. The structure of the β‧ phase in the Mg-Zr-O-N system has been investigated using X-ray powder methods. Its trigonally distorted fluorite-type structure (ordered anion vacancies) can be described by an arrangement of Bevan clusters (A7X12units) andA7X14units. At ∼975°C, a transition into a cubic fluorite-type phase with randomly distributed vacancies has been observed.
- Publication:
-
Journal of Solid State Chemistry France
- Pub Date:
- February 1997
- DOI:
- 10.1006/jssc.1996.7222
- Bibcode:
- 1997JSSCh.128..282L