Mechanism of thermoluminescence in magnesium oxide
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Abstract
Thermoluminescence (TL) induced by γ-rays in nominally pure polycrystalline MgO powders has been investigated. In addition to a high temperature peak around 650 K, which is also present in the unirradiated specimens, TL glow peaks are observed around 365, 435, 510 and 545 K. The role of transition metal impurities on TL behaviour has been studied by the doping technique. It is observed that Cr3+, Mn2+ and Ni2+ act as emission centres while Fe3+, Co2+ and Cu2+ act as quenchers. For a particular sample all γ-induced glow peaks give a similar emission spectrum which is characteristic of the activators present. Optical bleaching, isothermal decay and ESR studies have been used to study the trapping centres. It is shown that the charge carriers involved are holes from V-type defects. The dominant 365 K peak has been assigned to VM centres. A hole-release mechanism involving recombinations with electrons trapped at activators is proposed to explain the TL behaviour.
Keywords
Metal Impurity Emission Centre High Temperature Peak Trapping Centre Glow PeakPreview
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