Optical and photoelectrical studies of charge-transfer processes in YAlO3:Ti crystals

The donor and acceptor charge-transfer transitions in YAlO3:Ti3+/Ti4+ were investigated through absorption, emission, excitation, one-photon and two-photon photoconductivities, excited-state absorption, and thermoluminescence. The results are contrasted to similar studies previously made on Al2O3:Ti3+/Ti4+. The dominant Ti3+ population has a photoionization threshold at 37 000 cm(-1). The lowest energy Ti4+ charge transfer transition has its zero-phonon energy near to 33 900 cm(-1). The sum of these two quantities agrees with the reported band-gap energy of YAlO3. The position of the Ti3+/Ti4+ level in the band gap of YAlO3 is determined by these measurements. Stimulated emission from the (2)E State of Ti3+ is limited by photoionization from this state.