Na4La2−2xTb2x(CO3)5 nanophosphors: Hydrothermal synthesis and photoluminescence properties

Na4La2−2xTb2x(CO3)5 (x=0-0.5) nanophosphors were prepared via hydrothermal method, and the photoluminescence, concentration quenching, luminescence color chromaticity and thermal activation energy of samples were measured. The results indicate that samples with x values of 0-0.5 possess the pure monoclinic phase with an absorption edge at 250 nm. Na4La2−2xTb2x(CO3)5 (x=0-0.5) phosphors exhibit green luminescence, attributed to the 5D4→7FJ (J=6, 5, 4, 3) transitions of Tb3+. The concentration quenching takes place at about x=0.3, but no decreased luminescence intensity is observed; moreover, the activation energy of thermal quenching of Na4LaTb(CO3)5 nanophosphor was calculated to be 0.116 eV. The luminescence properties of Na4La2−2xTb2x(CO3)5 are benefited from its structural characteristics: long distance between Tb3+ ions and the ordered distribution of Tb3+ ions.