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Visible Spectroscopy of Irradiated High‐Alkali Borate and Mixed‐Alkali Phosphate Glasses
Author(s) -
BARKATT A.,
ANGELL C. A.,
MILLER J. R.
Publication year - 1981
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.1151-2916.1981.tb10249.x
Subject(s) - alkali metal , metaphosphate , boron , electron , phosphate glass , absorption (acoustics) , absorption spectroscopy , glass transition , analytical chemistry (journal) , borate glass , chemistry , spectroscopy , thermal stability , ion , inorganic chemistry , materials science , phosphate , physics , organic chemistry , chromatography , quantum mechanics , composite material , polymer
Expectations of increased stability for trapped electrons in high‐alkali glasses, based on extrapolations from observations on low‐alkali borate glasses, are not borne out. In 69Na 2 O‐31B 2 O 3 glass, electron centers have approximately the same thermal stability as in Na 2 O·2B 2 O 3 glass. In Na 2 Oplus;P 2 O 5 glasses the lifetimes, 3 · 0.5 μS, of transiently trapped electrons as well as their absorption spectra prove to be independent of increase of Na 2 O content from 50 to 60 mol%. The same composition change destabilizes “permanent” hole centers. Exchange of Na 2 O with K 2 O in the metaphosphate glass also has no effect on the trapped electron lifetime. Small linear shifts in the trapped‐hole absorption peak wavelengths are observed in the latter case. The most important positive finding in the phosphate glasses is a pronounced mixed‐alkali effect on the yield of transiently trapped electrons and holes and of permanently trapped holes. The yield is a minimum at Na:K=1:1, due either to the elimination of trap sites or to the reduction of alkali ion mobilities which play a role in trap formation.