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Title: Effects of composition and growth parameters on phase formation in multicomponent aluminum garnet crystals
The effects of composition on the phase formation of multicomponent garnet crystals grown via directional solidification by the micro-pulling-down method are studied. A relatively wide range of rare-earth (RE) average ionic radii (AIR) is explored by formulating ten compositions from the system (Lu,Y,Ho,Dy,Tb,Gd) 3 Al 5 O 12 . Crystals were grown at either 0.05 or 0.20 mm min −1 . The hypothesis is that multicomponent compounds with large AIR will form secondary phases as the single-RE aluminum garnets formed by larger Tb 3+ or Gd 3+ ; this will result in crystals of poor optical quality. Crystals with large AIR have a central opaque region in optical microscopy images, which is responsible for their reduced transparency compared to crystals with small AIR. Slow pulling rates suppress the formation of the opaque region in crystals with intermediate AIR. Powder and single-crystal X-ray diffraction and electron probe microanalysis results indicate that the opaque region is a perovskite phase. Scanning electron microscopy and energy dispersive spectroscopy measurements reveal eutectic inclusions at the outer surface of the crystals. The concentration of the eutectic inclusions increases with increasing AIR.  more » « less
Award ID(s):
1846935
PAR ID:
10387373
Author(s) / Creator(s):
; ; ; ; ;
Date Published:
Journal Name:
Acta Crystallographica Section B Structural Science, Crystal Engineering and Materials
Volume:
78
Issue:
2
ISSN:
2052-5206
Page Range / eLocation ID:
476 to 484
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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