Thermal Annealing Free Radicals in γ-Irradiated KDP and DKDP Crystals

Electron paramagnetic resonance (EPR) investigation of the γ-irradiated crystals of potassium dihydrogen phosphate (KH
₂
PO
₄
, KDP) and its deuterated analogue (KD
₂
PO
₄
, DKDP) is carried out. It is found that γ-irradiation leads to the formation of the thermally stable impurity arsenic-centered and intrinsic phosphorus-containing free radicals. Thermal annealing of the crystals in the temperature range of 90-160°C has been conducted. It is established that the thermal stability of the intrinsic defects is higher in comparison with the impurity ones. The nature of the phosphorus-containing free radicals is discussed.