EPR Studies of the Defect Centers in γ-Irradiated KH2PO4, NH4H2PO4and Ba(H2PO4)2Single Crystals: Effects of Impurities and Thermal Annealing

The CrO 4 2- impurity has been found to be very effective in stabilizing a phosphorus oxyradical produced by γ-irradiation at room temperature in KH 2 PO 4 and NH 4 H 2 PO 4 crystals. A similar radical species can be observed in pure Ba(H 2 PO 4 ) 2 crystals γ-irradiated at room temperature. The observed principal values of the g -factor and the 31 P hyperfine splitting indicate that this radical species could be the [PO 5 ] 2- or [O 3 POO] 2- .