Electron paramagnetic resonance techniques were used to study 3 defects in monocrystalline samples. The latter were irradiated with -rays at room temperature, and studied at 77K. The holes were identified as being O--Al3+, O--In3+ and O--H+ centers. An analysis of the data led to a model in which the holes were assumed to be trapped on bridging O ions between two Ti ions. The holes in the O--Al3+ (In3+) centers were stabilized by the nearest-neighbor Ti vacancy, and Al3+ (In3+) ions substituted for K ions. In the case of the O--H+ center, the hole was stabilized by the nearest-neighbor K vacancy and OH group.

R.I.Mashkovtsev, L.I.Isaenko: Solid State Communications, 1995, 95[10], 739-43