Spectroscopic properties of LaGaO3:V,Nd3+ nanocrystals as a potential luminescent thermometer

Abstract

In this work we present the spectroscopic properties of LaGaO₃:V,Nd³⁺ nanocrystals, which have been successfully obtained by the Pechini method. This is the first study where vanadium ions were applied in a LaGaO₃ lattice for a non-contact luminescent thermometer. It was found that vanadium ions in the LaGaO₃ matrix appear in three oxidation states, namely V⁵⁺, V⁴⁺ and V³⁺. It was found that the relative emission intensities of various states of vanadium ions depend strongly on grain size and therefore the emission color of LaGaO₃:V can be easily modulated via the annealing temperature. The spectroscopic properties of this material were investigated in a wide temperature range (−150–300 °C). It was found that in the case of V-singly doped nanocrystals, the V⁴⁺ ions, reveal the best temperature sensing performance with high relative sensitivity (S = 1.76% °C⁻¹) and broad usable temperature range (−50–150 °C). The different rates of thermal luminescence quenching of the vanadium ions provide three forms of non-contact temperature sensor, namely LaGaO₃:V⁵⁺,Nd³⁺, LaGaO₃:V⁴⁺,Nd³⁺ and LaGaO₃:V³⁺,Nd³⁺. The highest sensitivities were found to be 1% °C⁻¹ (at −5 °C and 90 °C), 0.49% °C⁻¹ (at −20 °C) and 1.44% °C⁻¹ (at 75 °C) for LaGaO₃:V⁵⁺,Nd³⁺, LaGaO₃:V⁴⁺,Nd³⁺ and LaGaO₃:V³⁺,Nd³⁺, respectively.