Microwave hydrothermal synthesis and upconversion luminescence properties of $$hbox {Yb}^{3+}$$/$$hbox {Tm}^{3+}$$Tm3+ co-doped $$hbox {NaY}(hbox {MoO}_{4})_{2}$$NaY(MoO4)2 phosphor

Tetragonal (text {NaY}(text {MoO}_{4})_{2}) (NYM) phosphors co-doped with (hbox {Yb}^{3+}) and (hbox {Tm}^{3+}) ions were synthesized through microwave hydrothermal method followed by calcining treatment. Powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy and photoluminescence spectra were used to characterize the properties of as-prepared samples. The results show that (hbox {Yb}^{3+})/(hbox {Tm}^{3+}) co-doped NYM displayed bright blue emission near 472 and 476 nm ((^{1}hbox {G}_{4}rightarrow {}^{3}hbox {H}_{6}) transition), strong near-infrared upconversion (UC) emission around 795 nm ((^{3}hbox {H}_{4}rightarrow {}^{3}hbox {H}_{6}) transition). The optimum doping concentrations of (hbox {Yb}^{3+}) and (hbox {Tm}^{3+}) for the most intense UC luminescence were obtained, and the related UC mechanism of (hbox {Yb}^{3+})/(hbox {Tm}^{3+}) co-doped NYM depending on pump power was studied in detail.