Luminescent Properties of Tb³⁺ in Oxygen-Dominated Compounds

Host lattice dependences of luminescence spectra and relaxation properties of T b 3+ are described. Reduced matrix elements relevant to the transitions are calculated and compared with observations. The spectra and the decay times of the 5 D 4 → 7 F J transitions are in qualitative agreement with the calculations. The electric-dipole transition of 5 D 4 → 7 F 5 has the largest probability in the 5 D 4 → 7 F J emission transitions within the framework of the Judd-Ofelt approximation. When the crystal field acting on T b 3+ is very strong, the intensity of 5 D 4 → 7 F 3 can become comparable to that of 5 D 4 → 7 F 5 . Magnetic-dipole transitions always have the largest probability for 5 D 4 → 7 F 5 . Spontaneous multiphonon relaxation of 5 D 3 → 5 D 4 is sometimes a dominant decay mechanism of the 5 D 3 state. The observed multiphonon relaxation rates are ∼2×10 2 in YPO 4 -, ∼8×10 3 in YBO 3 - and ∼2×10 4 in ScBO 3 -groups in units of sec -1 .