Accession Number : ADA337444

Title :   Modeling of Defects in Ceramic Oxides YAG

Descriptive Note : Final rept. 1 Sep 96-31 Aug 97

Corporate Author : MICHIGAN TECHNOLOGICAL UNIV HOUGHTON DEPT OF PHYSICS

Personal Author(s) : Pandey, Ravi

PDF Url : ADA337444

Report Date : 18 JAN 1998

Pagination or Media Count : 31

Abstract : Native point defects in Y3Al5O12 (YAG) were studied in the framework of the pair-potential approximation coupled with the shell model description of the lattice ions. For the perfect lattice, a new set of potential parameters were obtained which reproduce structure, elastic and dielectric constants of YAG very well. The calculated formation energies for native point defects predict that the antisite disorder is preferred over the Frenkel and Schottky like disorder in YAG. The calculated value of the distortion caused by the antisite Y sub Al are in excellent agreement with the EXAFS measurements. In non-stoichiometric YAG, the calculated reaction energies indicate that excess Y2O3 or Al2O3 is likely to be accommodated by the formation of antisite rather than vacancies in the lattice.

Descriptors :   *YTTRIUM ALUMINUM GARNET, *POINT DEFECTS, SIMULATION, CERAMIC MATERIALS, DISTORTION.

Subject Categories : Ceramics, Refractories and Glass
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE