High temperature photoluminescence sensitivity of Te4+ in silver nanoparticle tellurite glasses: Application as optical temperature sensor

Abstract

Tellurite glasses with the composition (in mol%) (100-x)(75TeO₂:25Li₂O):xAgNO₃ (x = 0, 0.6, and 1.2) were synthesized at 800 °C in an ambient atmosphere, for investigation of the influence of Ag nanoparticles on the Te⁴⁺ semi metal ion photoluminescence (³T_1 u → ¹A_1 g transition). The temperature dependence of the Te⁴⁺ emission was evaluated, aiming at application of the glass as an optical temperature sensor. A structural investigation of the samples was performed using X-ray diffractometry and Raman spectroscopy. The UV-Vis optical characteristics of the materials were determined by absorption, photoluminescence, photoluminescence excitation, and lifetime measurements. The sensitivity of the optical temperature measurement was determined based on the parameters emission lifetime, photoluminescence excitation intensity, and photoluminescence intensity ratio. The results showed that the silver nanoparticles increased the Te⁴⁺ PL intensity in the red region. For optical temperature sensing, a decrease in the Te⁴⁺ PL intensity, combined with a blue shift, occurred when the temperature was increased from ambient to 353 K, resulting in a maximum relative sensitivity of 3.7 %/K at room temperature. This high sensitivity indicated the suitability of the tellurite system as a potential candidate for application as an optical temperature sensor.