Growth, optical spectroscopy and crystal field investigation of YAl3(BO3)4 single crystals doped with tripositive praseodymium.

Single crystals of YAl3(BO3)4 doped with 1 and 10% Pr3+ were grown by spontaneous nucleation from a K2Mo3O10 and B2O3 flux. Polarised absorption and luminescence spectra in the visible, near infrared and infrared ranges were recorded at room and low temperatures on ground and polished samples of about 1 mm thickness. The microsymmetry of the Pr3+ sites is D3. The observed transitions were assigned and analysed on the basis of the selection rules for the D3 point group. A set of free ion and crystal field parameters in reasonable agreement with the observed energy level structure is reported. The possible applications of the material in the field of optical devices are considered.