The influence of grain size and vanadium concentration on the spectroscopic properties of YAG:V~(3+),V~(5+) and YAG: V, Ln~(3+) (Ln~(3+) = Eu~(3+), Dy~(3+), Nd~(3+)) nanocrystalline luminescent thermometers

摘要

The first demonstration of using V-based phosphor as a luminescent temperature sensor is presented. The luminescent properties of YAG:V3+, V5+and YAG:V Ln3+(Ln3+ = Eu3+, Nd3+and Dy3+) nanocrystals were investigated in a wide range of temperature (–150 °C–300 °C). The influence of dopant concentration and size of the nanocrystals on the emission color output of the YAG:V3+, V5+was analyzed. The provided analysis reveals that V3+and V5+are mainly localized in octahedral sites of Al3+of core part of the nanocrystals and surface tetrahedral sites of Al3+, respectively. The emission spectra consists of two broad emission bands, attributed to the CT emission of V5+(at 520 nm) and3T2g → 3T1gelectronic transition emission of V3+(at 820 nm). It was found that emission color output of the YAG:V3+, V5+nanocrystals can be modulated either by the vanadium concentration or by the size of nanocrystals. Based on the V3+to V5+emission intensity ratio (LIR) in the temperature range from −150 °C to 300 °C self-reference thermometer was defined, which reveals 0.7%/°C of sensitivity at the physiological temperature and increases above 4% in 250–300 °C. However its usable temperature range was strongly restricted. It was showed that by the appropriate choice of lanthanide co-dopants, the temperature range in which high sensitivity can be modulated (0.4%/°C at 100 °C for YAG:V,Eu3+; 4%/°C at −150 °C for YAG:V,Dy3+; and 0.8%/°C at 300 °C for YAG:V,Nd3+).