Enhancing the Relative Sensitivity of V5+, V4+ and V3+ Based Luminescent Thermometer by the Optimization of the Stoichiometry of Y3Al5-xGaxO12 Nanocrystals

Abstract

In this work the influence of the Ga³⁺ concentration on the luminescent properties and the abilities of the Y₃Al_5-xGa_xO₁₂: V nanocrystals to noncontact temperature sensing were investigated. It was shown that the increase of the Ga³⁺ amount enables enhancement of V⁴⁺ emission intensity in respect to the V³⁺ and V⁵⁺ and thus modify the color of emission. The introduction of Ga³⁺ ions provides the appearance of the crystallographic sites, suitable for V⁴⁺ occupation. Consequently, the increase of V⁴⁺ amount facilitates V⁵⁺ → V⁴⁺ interionic energy transfer throughout the shortening of the distance between interacting ions. The opposite thermal dependence of V⁴⁺ and V⁵⁺ emission intensities enables to create the bandshape luminescent thermometr of the highest relative sensitivity of V-based luminescent thermometers reported up to date (S_max, 2.64%/°C, for Y₃Al₂Ga₃O₁₂ at 0 °C). An approach of tuning the performance of Y₃Al_5-xGa_xO₁₂: V nanocrystals to luminescent temperature sensing, including the spectral response, maximal relative sensitivity and usable temperature range, by the Ga³⁺ doping was presented and discussed.

Keywords: gallium; garnets; inorganic nanocrystals; luminescence; luminescent nanothermometry; vanadium.