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Primary and Secondary Phase Separation in CdF 2 ‐LiF‐AlF 3 ‐PbF 2 Glasses
Author(s) -
RANDALL MICHAEL S.,
SIMMONS JOSEPH H.,
ELBAYOUMI OSAMA H.
Publication year - 1988
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1988.tb05805.x
Subject(s) - volume fraction , precipitation , phase (matter) , primary (astronomy) , decomposition , fraction (chemistry) , volume (thermodynamics) , analytical chemistry (journal) , spheres , materials science , matrix (chemical analysis) , mineralogy , chemistry , thermodynamics , chromatography , composite material , physics , organic chemistry , astronomy , meteorology
Occurrence of primary and secondary phase separation in the CdF 2 ‐LiF‐AlF 3 ‐PbF 2 glass system is observed. A primary phase separation, which is characterized by the formation of a small volume fraction of Cd‐rich, Pb‐deficient spheres whose size is on the order of 5μ is found to form upon cooling. A secondary phase separation initiates with precipitation of Pb‐rich microspheres (about 4nm (40 Å) in diameter) in a Cd‐rich matrix. The Pb‐rich spheres develop with heat treatment 35°C above the glass transition temperature. They increase in volume fraction while changing composition and then grow slightly. As the material is further heat‐treated, the Pb‐rich regions crystallize. A pseudobinary model explaining the occurrence of both primary and secondary decomposition phenomena is presented.