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Impurity‐Associated Colour Centres in Mg‐ and Ca‐Doped Al 2 O 3 Single Crystals
Author(s) -
Kulis P. A.,
Springis M. J.,
Tale I. A.,
Vainer V. S.,
Valbis J. A.
Publication year - 1981
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.2221040241
Subject(s) - electron paramagnetic resonance , hyperfine structure , impurity , luminescence , ion , doping , vacancy defect , unpaired electron , absorption spectroscopy , absorption band , chemistry , analytical chemistry (journal) , crystallography , spectral line , atomic physics , materials science , nuclear magnetic resonance , physics , optics , chromatography , optoelectronics , organic chemistry , astronomy
In Mg‐ and Ca‐doped α‐Al 2 O 3 crystals irradiated by X‐rays at 80 K new paramagnetic colour centres are observed having an absorption band at about 255 nm and an emission band at 310 nm. The hyperfine structure of the EPR spectrum indicates that the unpaired electron spin interacts mainly with two Al 27 nuclei. The optical and EPR spectra are consistent with the model of a centre involving one electron trapped at an anion vacancy adjoining the substitutional divalent ion (F Mg or F Ca ). The luminescence band at 290 nm observed in the TSL peak at 225 K is suggested to result from the recombination of the holes with the F Mg (F Ca ) centres.