Redox reaction and thermoluminescence in dysprosium-doped potassium sulphate phosphor

The thermoluminescence (TL) of dysprosium-(Dy)-doped potassium sulphate was studied above room temperature. As-grown samples were found to be transparent. Upon heavy γ-irradiation these phosphors acquired a blue tinge which is attributed to Dy2+ centres formed during irradiation as a result of electron trapping by Dy3+. The absorption due to these colour centres was detected in the 1.5-2.7 eV region. TL glow showed a three peak pattern. The TL emission spectrum contained the characteristic emission bands of Dy3+ due to transitions from the 4F 9 2 to the 6H levels. The TL mechanism is identified as due to the usual redox reaction prevalent in rare-earth doped phosphors. © 1993.