INHOMOGENEITY OF THALLIUM HALIDE MIXED CRYSTALS AND ITS ELIMINATION

Abstract

A study was made of the optical inhomogeneity of prisms used in IR spectroscopy, which are cut from mixed crystals of thallium halides. The cause of the defect was determined to be the use of incorrect minimum melting points of the compositions from which the crystals were grown. The freezing points of thallium halides and the minimum freezing points of the binary systems (TlCl with TlBr and TlBr with TlI were determined by cooling the melted samples and measuring the temperature with an Fe-Constantan thermocouple. The freezing points were higher than those of Moenkemeyer (Neves Jahrb. Mineral. Geol. Pal. 22, Beilage-Band, 1906). Crystals of binary systems were grown on the basis of the new data, and the greatest deviation of the lattice constant along the crystal length was determined to be no more than 5 x 10 to the minus 5th power. These results show that the optical inhomogeneity was caused by the incorrect composition of the melt. The refractive index variation in the new crystals was less than 1 x 10 to the minus 5th power.

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Document Details

Document Type
Technical Report
Publication Date
Mar 01, 1953
Accession Number
AD0008948

Entities

People

  • A. Smakula
  • J. Kalnajs
  • V. Sils

Organizations

  • Massachusetts Institute of Technology

Tags

Communities of Interest

  • Ground and Sea Platforms

DTIC Thesaurus Topics

  • Accuracy
  • Chemical Analysis
  • Chemical Composition
  • Chemistry
  • Halides
  • Materials
  • Materials Science
  • Measurement
  • Melting Point
  • Phase Diagrams
  • Physical Properties
  • Refractive Index
  • Temperature Gradients
  • Thermal Diffusion
  • Thermal Expansion
  • Transition Temperature
  • X Rays

Readers

  • Materials Science and Engineering.
  • Thermal Physics or Thermal Science.