Accession Number : AD0641324

Title :   THE EFFECT OF HIGH PRESSURE ON B203: CRYSTALLIZATION, DENSIFICATION, AND THE CRYSTALLIZATION ANOMALY.

Descriptive Note : Technical rept.,

Corporate Author : HARVARD UNIV CAMBRIDGE MASS DIV OF ENGINEERING AND APPLIED PHYSICS

Personal Author(s) : Uhlmann,D. R. ; Hays,J. F. ; Turnbull,D.

Report Date : JUL 1966

Pagination or Media Count : 54

Abstract : The crystallization and densification of B2O3 at high pressure were investigated using a Bridgman anvil device. Crystallization was observed at pressures as low as 4 kilobars and at temperatures as low as 210C. A marked effect of water in increasing the overall crystallization rate, and the increase in this rate with increasing temperature, were demonstrated. Increases in density as large as 17 per cent, and a strong effect of temperature in increasing densification, were likewise shown. The crystallization behavior is discussed in terms of the kinetic formalism developed previously and is related to past observations on SiO2 at high pressure. The densification results are considered in light of the results of others workers on B2O3 and SiO2. The anomalous crystallization behavior of B2O3 is discussed, and a number of hypotheses are advanced to explain the observations. These hypotheses are evaluated in relation to the results of the high pressure study. (Author)

Descriptors :   (*BORON COMPOUNDS, HIGH PRESSURE), (*CRYSTALLIZATION, BORON COMPOUNDS), OXIDES, DENSITY, GLASS, PHASE STUDIES, WATER, THEORY, THERMOCHEMISTRY

Subject Categories : Ceramics, Refractories and Glass
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE