ELECTRON-PARAMAGNETIC RESONANCE AND OPTICAL-SPECTRA OF TI-3+-DOPED YALO3

The electron paramagnetic resonance (EPR), optical absorption and luminescence spectra of Ti3+ ions in YAlO3 have been measured at low temperatures. The optical absorption spectrum is composed of two broad bands with peak wavelengths of 434 and 492 nm, the energy separation of which is due to splitting of the excited 2E state. The broad-band luminescence with a peak at a wavelength of 605 nm at low temperatures is accompanied by a single sharp zero-phonon line at 540 nm. The absorption and luminescence spectra are strongly polarized. The spin-Hamiltonian parameters of Ti3+ ions substituting for Al3+ ions in sites with orthorhombic symmetry were determined from the orientation dependence of the EPR Spectra to be g(x) = 1.795(5), g(y) = 1.850(5) and g(z) = 1.950(5). The experimental g-tensor is compared with that calculated in terms of the mixing of the higher components of the 2T2 ground states and the 2E excited states into the lowest 2T2 ground state by spin-orbit interaction, the energies of these levels having been estimated from the broad-band absorption spectrum and the zero-phonon lines of the emission spectrum.