Habit Modification of SiO2 Doped Y3Al5O12, Y3Fe5O12, and Y3Ga5O12 Garnets.
Rept. for Jun 69-Nov 71,
AEROSPACE CORP EL SEGUNDO CALIF LAB OPERATIONS
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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