Enhancing upconversion emission and temperature sensing modulation of the La2(MoO4)3: Er3+, Yb3+ phosphor by adding alkali metal ions

Trivalent Er 3+ -doped La 2 (MoO 4 ) 3 upconversion phosphors with intense green emmision were synthesized at 800 °C by the solid-state reaction route, promoting the development of novel optical thermometry. The color emitted from the samples was minorly affected by the excitation power and doping concentration. Yb 3+ is a better sensitizer for the La 2 (MoO 4 ) 3 : Er 3+ phosphor and it can enhance the emission intensity when a certain amount is co-doping in the system. The up-conversion luminescent mechanism was investigated using the pump power-dependent UC emission spectra. Alkali metal doping increased the up-conversion emission intensities drastically, and Li + ions can enhance the luminous intensity by more than 20 times. The fluorescence intensity ratio of the transition emission 2 H 11/2 - 4 I 15/2 and 4 S 3/2 - 4 I 15/2 was used to study upconversion optical temperature sensing. The sensitivity changes from doping with diverse alkali metal ions and their effects on the optimal temperature range are discussed in detail. Alkali metal ions doping extended the temperature range, indicating that this phosphor is a potential candidate for temperature-sensing probes.