Neodymium doped lanthanum oxysulfide as optical temperature sensors

The fluorescence intensity ratio (FIR) technique for temperature sensing has been demonstrated in La2O2S:Nd3+ phosphors. The phosphors were extensively characterized using various methods such as X-ray diffraction, photoluminescence excitation, and photoluminescence spectra. Upon ultraviolet–visible (UV–vis) or near-infrared (NIR) light excitation, two intense NIR emissions of Nd3+ peaking at 897nm and 1074nm corresponding to transitions of 4F3/2→4I9/2 and 4F3/2→4I11/2 were generated at room temperature. NIR emission of Nd3+ in a wide temperature range from 30K to 600K was investigated. Experimental results show that the temperature evaluation can be realized by monitoring the emission peak position, measuring the fluorescence intensity ratio of 4F5/2 and 4F3/2 or that of the two Stark components of the 4F3/2 level in the bulk La2O2S:Nd3+. Furthermore, the effective energy difference of the thermalized levels 4F5/2 and 4F3/2, and 4F3/2 two Stark components were 987cm−1 and 110cm−1, respectively. Those results imply that La2O2S:Nd3+ phosphor is a potential candidate for the optical temperature sensor. •The temperature evaluation can be realized either by monitoring the emission peak position or measuring the fluorescence intensity ratio in this report.•The sensitivity (S) value in La2O2S:Nd3+ is 1.58%K−1 at 300K, which is superior to the sensitivity of 1.20%K−1 for Er3+/Yb3+ co-doped NaYF4.•The 4F3/2→4I11/2 emission peak of Nd3+ shifted with a rate of 0.0034nm/K was obtained.