摘要
Luminescent materials for application in temperature sensing have caught a lot of interest in recent years.Particularly erbium(Er^(3+))-doped fluoride-based materials(EFM),which are readily accessible by near-infrared(NIR)excitation to produce efficient photon conversion.It has been established that ytterbium(Yb^(3+))may improve the performance of EFMs in both bulk and nanostructured forms by energy transfer channels among rare-earth ions in interstitial clusters.In this work,a comprehensive analysis of the Er^(3+):Yb^(3+):CaF_(2)crystalline structure,photoluminescence,and energy transfer from Yb^(3+)to Er^(3+)is presented for powders prepared by combustion synthesis.The Er^(3+):Yb^(3+):CaF_(2)powders display exceptional photon down-shift and up-conversion when exposed to NIR light(λ=975 nm).The luminescence spectral change of the NIR emission around 1.5μm,which corresponds to the Er^(3+)electronic transition ^(4)I_(13/2)→^(4)I_(15/2),was investigated in a temperature range of 298-423 K for application in temperature sensing of biological systems exploring the third biological window.The luminescence intensity ratio technique was applied to the thermally coupled Stark sublevels of states^(4)I_(13/2)and^(4)I_(15/2)with the highest estimated temperature relative sensitivity being around 0.4%/K at 298 K.
基金
Project supported in part by the Brazilian Agency Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)。
