A facile approach to the synthesis of Er³⁺–Yb³⁺–Mo⁶⁺ co-doped TiO₂/Yb₂Ti₂O₇ electrospun nanofibers and high thermal sensitivity

Abstract

Er³⁺–Yb³⁺–Mo⁶⁺ co-doped TiO₂/Yb₂Ti₂O₇ up-conversion luminescent nanofibers have been successfully synthesized using the electrospinning technology followed by thermolysis. The effects of the precursor ratio and annealing process on up-conversion luminescent character were investigated. The phase of TiO₂ was determined to be either anatase or rutile. And the cubic Yb₂Ti₂O₇ in Er³⁺–Yb³⁺–Mo⁶⁺ co-doped TiO₂ phosphor was confirmed. After annealing at high temperature, the up-conversion luminescent intensity of the studied system increased obviously. The fluorescence intensity ratio (FIR) used to be made on the basis of green up-conversion emissions. It was studied as a function of temperature. The maximum rate of sensitivity was ~0.01 K⁻¹ in the range of 300–600 K. The results indicate that Er³⁺–Yb³⁺–Mo⁶⁺ co-doped TiO₂/Yb₂Ti₂O₇ phosphor is a brand-new material that meets the requirement of the optical temperature sensing.

Highlights

• Er³⁺–Yb³⁺–Mo⁶⁺ co-doped TiO₂/Yb₂Ti₂O₇ nanofibers have been synthesized by electrospinning technique and the followed thermolysis. The morphology of nanofibers was significantly changed after annealing at high temperature.

• The green up-conversion emission of Er³⁺ was enhanced by a high excited state energy transfer (HESET) with Yb³⁺–MoO₄²⁻ dimer in Er³⁺–Yb³⁺–Mo⁶⁺ TiO₂/Yb₂Ti₂O₇ nanofibers.

• The maximum sensitivity of Er³⁺–Yb³⁺–Mo⁶⁺ co-doped TiO₂/Yb₂Ti₂O₇ nanofibers was determined to be 0.01039 K¹ at 397 K, was better than other Er³⁺–Yb³⁺–Mo⁶⁺ co-doped materials.