Photoluminescence and Concentration Quenching Properties of BaMoO4:Tb3+ Phosphors

BaMoO4:Tb3+ phosphor powders were synthesized with different concentrations of Tb3+ ions using the solid-state reaction method. XRD patterns showed that all the phosphors, irrespective of the concentration of Tb3+ ions, had tetragonal systems with two main (112) and (004) diffraction peaks. The excitation spectra of the Tb3+-doped BaMoO4 phosphors consisted of an intense broad band centered at 290 nm in the range of 230-330 nm and two weak bands. The former broad band corresponded to the 4f8 > 4f75d1 transition of Tb3+ ions; the latter two weak bands were ascribed to the 7F2 -* 5D3 (471 nm) and 7F6 >5134 (492 nm) transitions of Tb3+. The main emission band, when excited at 290 nm, showed a strong green band at 550 nm arising from the 5134 >7F5 transition of Tb3+ ions. As the concentration of Tb3+ increased from 1 to 10 mol%, the intensities of all the emission lines gradually increased, approached maxima at 10 mol% of Tb3+ ions, and then showed a decreasing tendency with further increase in the Tb3+ ions due to the concentration quenching effect. The critical distance between neighboring Tb3+ ions for concentration quenching was calculated and found to be 12.3 A, which indicates that dipole dipole interaction was the main mechanism for the concentration quenching of the D-5(4) -> F-7(5) transition of Tb3+ in the BalVloO(4):Tb3+ phosphors.