Co-precipitation synthesis and thermally enhanced upconversion luminescence properties of ScPO4:Yb3+/Er3+ phosphors for temperature sensing

A series of ScPO4:Yb3+/Er3+ upconversion luminescent (UCL) materials with different ytterbium and erbium doping concentrations have been synthesized by a co-precipitation method. Concentration-dependent UCL spectra revealed that the optimal composition was realized for the 15 at%Yb3+ and 1.0 at% Er3+-doping concentration with a strong UCL. Temperature-dependent UCL spectra of ScPO4:Yb3+/Er3+ phosphors indicate that this phosphor possesses thermally enhanced UCL properties. Under the excitation of 980 nm laser, ScPO4:Yb3+/Er3+ can emit intense green and red located at 526/550 nm and 668 nm attributed to the characteristic transitions 2H11/2/4S3/2→4I15/2 and 4F9/2→4I15/2 of the Er3+ ion, respectively. In addition, the temperature sensing properties of the samples were investigated based on the thermally coupled energy levels (2H11/2 and 4S3/2) of Er3+. In the temperature range of 298∼573 K, the best relative sensitivity (Sr) is 1.28 %/K at 298 K. The above results indicate that ScPO4:Yb3+/Er3+ phosphors have excellent UCL performance and can be applied in luminescence display and temperature sensing.