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

In this work the influence of the Ga3+ concentration on the luminescent properties and the abilities of the Y3Al5-xGaxO12: 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%/degrees C, for Y3Al2Ga3O12 at 0 degrees C). An approach of tuning the performance of Y3Al5-xGaxO12: 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.