Accession Number:

AD0425921

Title:

CRYSTAL STRUCTURE, SYNTHESIS, AND MAGNETIC PROPERTIES OF CHRYSOBERYL,

Descriptive Note:

Corporate Author:

MASSACHUSETTS INST OF TECH CAMBRIDGE LAB FOR INSULATION RESEARCH

Personal Author(s):

Report Date:

1963-11-01

Pagination or Media Count:

23.0

Abstract:

Chrysoberyl, AL2BeO4, is isomorphous with olivine the space group is Pnma, orthorhombic, with a 9.404, b 5.476, and c 4.427 A. The O positions approximate hexagonal close packing with al cations occupying octahedral interstices and Be in tetrahedral sites. Accurate atomic coordinates were obtained by least-squares analysis of three-dimensional X-ray diffraction data. Both the octahedra and tetrahedra are distorted, showing significant deviations from their mean bond lengths A1-O 1.91 A and Be-O 1.63 A. Refinement of the crysoberyl structure showed that the two al octahedral sites differ significantly in size. Experimental evidence for selective substitution in A12-xFexBeO4 and A12-xCrxBeO4 solid solutions is presented. Magnetic-susceptibility data between 4.2 and 300 K were obtained for the A1, Cr2BeO4 solidsolution series. Author

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Distribution Statement:

APPROVED FOR PUBLIC RELEASE