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EPR and Kinetic Studies of Hydrogen Centers in Aluminoborate Glasses
Author(s) -
PONTUSCHKA W. M.,
ISOTANI S.,
PICCINI A.,
VUGMAN N. V.
Publication year - 1982
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.1151-2916.1982.tb10345.x
Subject(s) - hydrogen , electron paramagnetic resonance , chemistry , analytical chemistry (journal) , annealing (glass) , impurity , kinetic energy , spectral line , van der waals force , atomic physics , materials science , nuclear magnetic resonance , molecule , physics , organic chemistry , chromatography , quantum mechanics , astronomy , composite material
Barium aluminoborate glasses containing hydrogen as an impurity, irradiated at 77 K with X rays, show the characteristic doublet of atomic hydrogen in the EPR spectra when measured at T<200 K. The hfs constant of the H o i center is smaller than that of free atomic hydrogen, indicating that the attractive van der Waals interaction is more important than the repulsive Pauli exclusion forces in that glassy matrix. It is suggested on the basis of isochronal and isothermal annealing experiments that there are at least three different sites for hydrogen, each one contributing with Ist‐order decay kinetics. The activation energies found in 30 mol% BaO, 60 B 2 O 3 , 10 Al 2 O 3 glass are, respectively, equal to E 1 =(0.5±0.1), E 2 =(0.24±0.03), and E 3 =(0.16±0.03)×lO −19 J.