A four-mode optical thermometer designed in double perovskite Ca2GdNbO6:Bi3+,Eu3+

Abstract

High-sensitive multi-mode optical thermometry has become a superstar in the temperature sensing field and attracted great attention. Herein, a novel four-mode optical thermometer is designed in Eu3+ and Bi3+ co-doped double perovskite Ca2GdNbO6. The crystal structures of the host and the doped samples were characterized with X-ray diffraction patterns and Rietveld refinements. Under the excitation of 340 nm, the phosphors exhibit multiple emissions coming from Bi3+ and Eu3+. The energy transfer from Bi3+ to Eu3+ is proved in the perovskite and the transfer efficiency reaches as high as 92%. Benefiting from the different temperature-dependent photoluminescent properties of Bi3+ and Eu3+, a four-mode optical thermometer based on fluorescence intensity ratio, CIE coordinate, fluorescence lifetime, and excitation intensity ratio is realized in the Ca2GdNbO6:0.03Bi3+,0.01Eu3+ phosphor. The maximal relative sensitivities of the four modes are 1.90% K−1 at 460 K, 0.514% K−1 at 500 K, 2.69% K−1 at 437 K, and 1.43% K−1 at 310 K, respectively, most of which are higher than those of recently reported phosphors. These good thermometric performances suggest that Ca2GdNbO6:Bi3+,Eu3+ has a great potential application in temperature detection field.