Luminescence properties of Bi/Sm co-doped KGd(PO) phosphors for self-referencing optical thermometry.

Potassium gadolinium phosphates [KGd(PO)] co-doped with Bi/Sm phosphors were prepared by traditional solid-state method. Their structure, morphology, luminescence properties, energy transfer, temperature sensing performance and thermal stability have been systematically investigated. The emission and excitation spectra, as well as decay curves were recorded to study the luminescence mechanism. By co-doping Bi/Sm, white emission color can be obtained. In addition, the emission intensity ratios of Bi and Sm ions present excellent temperature sensing performance in a wide temperature range. The maximum relative sensitivities of KGd(PO) doped with Bi/Sm can reach to 3.13% K. In addition, KGd(PO):Bi,Sm phosphors exhibit high thermal stability of about 55.3% at 423 K compared to room temperature.