Step by step designing of sensitive luminescent nanothermometers based on Cr3+,Nd3+ co-doped La3−xLuxAl5−yGayO12 nanocrystals†
In this work we present step by step designing of sensitive luminescent thermometers utilizing Cr3+,Nd3+ co-doped La3−xLuxAl5−yGayO12 garnets. In order to achieve this purpose, modification of the local ion environment by the adjustment of the La3+ to Lu3+ and the Al3+ to Ga3+ ion ratios was performed. Additionally, the influence of the Cr3+ and Nd3+ ion concentration on the thermal quenching of Cr3+ luminescence was investigated. All of the abovementioned steps of the host stoichiometry optimization enabled us to obtain a relative sensitivity of luminescent thermometers based on the luminescence intensity ratio of Nd3+(4F5/2 → 4I9/2)/Cr3+(2E → 4A2) electronic transitions as high as S = 1.47% °C−1 at −150 °C and S = 1.23% °C−1 at 260 °C for La2LuGa5O12:1%Cr3+,5%Nd3+ nanocrystals. The presented studies provide the verification how stoichiometry of host material affect the relative sensitivity of transition metal/lanthanide ion based luminescent thermometers, enabling knowledgeable designing of highly sensitive luminescent thermometers.