CRYSTAL STRUCTURE, SYNTHESIS, AND MAGNETIC PROPERTIES OF CHRYSOBERYL,

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 A1(2-x)Fe(x)BeO4 and A1(2-x)Cr(x)BeO4 solid solutions is presented. Magnetic-susceptibility data between 4.2 and 300 K were obtained for the (A1, Cr)2BeO4 solidsolution series. (Author)

Document Details

Document Type
Technical Report
Publication Date
Nov 01, 1963
Accession Number
AD0425921

Entities

People

  • Robert E. Newnham

Organizations

  • Massachusetts Institute of Technology

Tags

DTIC Thesaurus Topics

  • Crystal Structure
  • Crystals
  • Diffraction
  • Magnetic Properties
  • Physical Properties
  • Solid Solutions
  • Three Dimensional
  • X Rays
  • X-Ray Diffraction

Fields of Study

  • Chemistry

Readers

  • Materials Science and Engineering.
  • Organic Chemistry

Technology Areas

  • Space