THE EFFECT OF HIGH PRESSURE ON CRYSTALLIZATION KINETICS: FUSED SILICA.

Abstract

A thermodynamic theory is developed for the effect of pressure on the kinetics of phase transformations. The results suggest that application of pressure may have a profound effect in increasing the rate of crystal nucleation, but that its effect on growth rate should generally be a smaller inhibitory one. Observations on SiO2 carried out in a Bridgman-anvil high pressure device demonstrated the occurrence of crystallization under conditions of temperature and pressure where none had been anticipated from the kinetic formalism. A number of hypotheses are suggested to account for the observations, the most satisfactory of which is based on the effect of water, and the possible existence of a water-rich region at the interface at high pressure, in enhancing the extent of crystallization in a given time. (Author)

Document Details

Document Type
Technical Report
Publication Date
Apr 01, 1966
Accession Number
AD0638140

Entities

People

  • D. R. Uhlmann
  • D. Turnbull
  • J. F. Hays

Organizations

  • Harvard University

Tags

DTIC Thesaurus Topics

  • Critical Temperature
  • Crystallization
  • Crystals
  • Glass Transition Temperature
  • High Pressure
  • Hypotheses
  • Kinetics
  • Nucleation
  • Observation
  • Optical Materials
  • Phase Transformations
  • Transition Temperature

Readers

  • Materials Science and Engineering.
  • Theoretical Analysis.