Vertical Bridgman growth and optical properties of Pr3+-doped NaY (MoO4)2 crystal

Pr3+:NaY(MoO4)(2) crystals with dopant concentration from 0.1 to 1.5 mol% have been successfully grown by the vertical Bridgman method using spontaneous crystallization. The as-grown Pr3+-doped NaY(MoO4)(2) crystals presented black-green color, and the annealed crystal samples presented transparency with faint green coloration. The mechanisms of eliminating color centers by thermal annealing are explained in detail. The Raman, absorption, emission spectra and fluorescence decay curves of Pr3+-doped NaY(MoO4)(2) crystals were studied systematically. The concentration segregation coefficients of four crystal samples are maintained in the range of 1.1-1.6. The Judd-Ofelt parameters were calculated according to the measured absorption spectra. The emission spectra showed that when Pr3+-doped NaY(MoO4)(2) crystals were excited at 475 nm, orange-red broadband emission (606-652 nm) with a strong dependence on the Pr3+ ion concentration could be observed. The emission cross-sections at 606 and 652 nm were calculated as 2.73 x 10(-20) and 2.03 x 10(-20) cm(2), respectively. And the possible processes of energy transfer between [MoO4](2-) anion groups and Pr3+ ions are also discussed. The longest average decay time (tau = 43.59 mu s) was obtained at 606 nm when the Pr3+ concentration is 0.1%. The excellent luminescence performance in the orange-red region indicates that the Pr3+-doped NaY(MoO4)(2) crystals have potential applications in tunable orange-red laser.