Facile template free synthesis of KLa(MoO4)2:Eu3+,Tb3+ microspheres and their multicolor tunable luminescence

Trivalent rare-earth (RE(3+) = Eu(3+), Tb(3+)) ion activated KLa(MoO4)2 microspheres have been synthesized at 180 °C via a facile hydrothermal route without using any templates, surfactant, or other organic additives. X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM), photoluminescence (PL), and photoluminescent excitation spectra (PLE) were employed to characterize the samples. It is found that the pH value in the initial solution is responsible for crystal phase, shape determination and emission intensity of final products. The possible formation mechanism for products with uniform spheres has been presented. Furthermore, a systematic study on the photoluminescence of RE(3+) (RE(3+) = Eu(3+), Tb(3+)) doped KLa(MoO4)2 samples has been explored in order to obtain the multicolor tunable emission by varying the Tb(3+)/Eu(3+) ratio. The tunable luminescence may be potentially applied in fields such as solid state lighting and field emission displays.