Accession Number : AD0745453

Title :   Habit Modification of SiO2 Doped Y3Al5O12, Y3Fe5O12, and Y3Ga5O12 Garnets.

Descriptive Note : Rept. for Jun 69-Nov 71,

Corporate Author : AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS

Personal Author(s) : Chase,Armond B. ; Osmer,Judith A.

Report Date : 10 APR 1972

Pagination or Media Count : 21

Abstract : The habits of single crystals of the synthetic garnets, when grown from a SiO2 contaminated PbO-PbF2 flux, are dependent on the concentration of SiO2 in the melt. Y3Ga5O12 and Y3Fe5O12 crystals have a pure (211) habit when grown from an undoped melt. The crystal habit changes smoothly from (211) to (110) to (110) approximately to (100) for Y3Ga5O12, and from (211) to (110) for Y3Fe5O12 with increasing SiO2 in the melt. Y3Al5O12 crystals change from (211) > (110) to (211) or from (110) > (211) to (110) with increasing SiO2 in the melt. Analysis and comparison of the variation in oxygen positions in garnets of various composition indicate a tetrahedral site distortion for doped crystals that leads to surface energy conditions favoring a (110) habit for Si4+ doped crystals of Y3Fe5O12 and Y3Ga5O12. On the other hand, the habit change of Y3Al5O12 is believed to be dependent on a surface-contamination mechanism. (Author)

Descriptors :   (*CRYSTAL GROWTH, YTTRIUM COMPOUNDS), (*CRYSTAL STRUCTURE, GARNET), ALUMINATES, FERRATES, GALLIUM COMPOUNDS, DOPING, SILICON DIOXIDE, SINGLE CRYSTALS

Subject Categories : Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE