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Viscosity and Thermal Expansion of Alkali Germanate Glasses
Author(s) -
SHELBY J. E.
Publication year - 1974
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.1151-2916.1974.tb11376.x
Subject(s) - germanate , alkali metal , thermal expansion , viscosity , oxide , thermodynamics , mineralogy , atmospheric temperature range , materials science , analytical chemistry (journal) , chemistry , composite material , metallurgy , physics , organic chemistry , optoelectronics , doping
Transformation‐range viscosities are reported for Na 2 O‐, K 2 O‐, Rb 2 O‐, and Cs 2 O‐GeO 2 glasses. A minimum in viscosity occurs between 1 and 5 mol% alkali oxide and a maximum between 17 and 22 mol% alkali oxide. The thermal‐expansion coefficients of the Na 2 O‐GeO 2 glasses also exhibit a minimum at < 5 mol% Na 2 O. The accepted structural model for alkali germanate glasses does not predict the minimum at low R 2 O concentrations. A modification of this model is suggested to explain these data.