Photoluminescence properties and energy transfer of NaY(MoO4)2:R (R = Sm3+/Bi3+, Tb3+/Bi3+, Sm3+/Tb3+) phosphors

NaY(MoO 4 ) 2 :R (R   =   Sm 3+ /Bi 3+ , Tb 3+ /Bi 3+ , Sm 3+ /Tb 3+ ) phosphors are synthesized by solid-state reaction method in air. The crystal structures, excitation and emission spectra, luminescence properties, the lifetimes, and the dopant concentration influences are investigated. The emission intensity of activators Sm 3+ and Tb 3+ can be enhanced ∼3.04 and 1.64 times due to energy transfer (ET) from Bi 3+ to Sm 3+ /Tb 3+ . NaY(MoO 4 ) 2 :Sm 3+ , Tb 3+ phosphor with excitation 300   nm shows a tunable emission from red to yellow with change Sm 3+ or Tb 3+ ion concentration. Emission intensity of NaY(MoO 4 ) 2 :Sm 3+ phosphor can be enhanced ∼2.24 times via co-doping Tb 3+ ion owing to ET from Tb 3+ to Sm 3+ ions. The results indicate that ET between sensitizer and activator (Bi 3+   →   Tb 3+ , Bi 3+   →   Sm 3+ , and Tb 3+   →   Sm 3+ ) is beneficial to improve the luminescence properties of activator (Sm 3+ and Tb 3+ ). ET and luminous meachanisms are explained by energy level diagrams of Bi 3+ , Tb 3+ , and Sm 3+ ions.