Accession Number : AD0717332

Title :   Phase Separation in GeO-GeO2 Glasses.

Descriptive Note : Interim technical rept.,

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

Personal Author(s) : DE Neufville,J. P. ; Turnbull,D.

Report Date : DEC 1970

Pagination or Media Count : 30

Abstract : A series of transparent homogeneous amorphous solids between GeO2 and GeO has been prepared by rapid quenching of liquids and by vapour depositions. Density and refractive index increase smoothly with increasing Ge/O ratio and provide a useful index of composition. Glasses in the range GeO-GeO(1.85) undergo a rapid exothermic transformation when heated above 400C accompanied by a pronounced blackening, an increase in refractive index, and a light decrease in density. Electron microscopy and diffraction results indicate that the transformation involves the precipitation on a 50-100 A scale of an amorphous tetrahedrally coordinated Ge-rich phase. The interconnected microstructure so produced is suggestive of spinodal decomposition. A transitional region near GeO(1.9) is characterized by sluggish phase separation kinetics and a dispersed particle morphology suggestive of a nucleation and growth precipitation mechanism. Glasses in the range GeO(1.9)-GeO2 show no evidence for phase separation. (Author)

Descriptors :   (*GERMANIUM COMPOUNDS, *PHASE STUDIES), OXIDES, GLASS, MICROSTRUCTURE, CHEMICAL PRECIPITATION, ELECTRON DIFFRACTION, ELECTRON MICROSCOPY, TRANSITION TEMPERATURE

Subject Categories : Physical Chemistry
      Ceramics, Refractories and Glass

Distribution Statement : APPROVED FOR PUBLIC RELEASE