A novel upconversion luminescence temperature sensing material: Negative thermal expansion Y2Mo3O12:Yb3+, Er3+ and positive thermal expansion Y2Ti2O7:Yb3+, Er3+ mixed phosphor

Highlights: • Composites prepared by rare earth doped positive and negative thermal expansion materials, which is advantage of temperature sensing application. • A novel upconversion luminescence temperature sensor based on FIR was obtained, the composites consists of Y₂Mo₃O₁₂ and Y₂Ti₂O₇. • The FIR (I₈₆₀/I₆₇₅) was researched in the range from 293K to 574K, which suggests that FIR increases with rising temperature. • The maximum relative sensitivity was 1.61%K^-1 in FIR(I₈₆₀/I₆₇₅) at 293K. The result suggests that the mixed phosphor exhibits potential application as a new temperature sensing device. -- Abstract: Thermal enhancement and quenching of upconversion luminescence of rare earth ions can be realized in the negative expansion and positive expansion hosts, respectively, which is advantage of temperature sensing applications. In this work, the negative expansion Y₂Mo₃O₁₂:Yb³⁺, Er³⁺ and positive thermal expansion Y₂Ti₂O₇:Yb³⁺, Er³⁺ phosphors were prepared, respectively. The temperature dependence of upconversion luminescence demonstrated that the green, red and near infrared upconversion luminescence of Y₂Mo₃O₁₂:Yb³⁺, Er³⁺ phosphor increases with the increasing of temperature, while the upconversion luminescence of Y₂Ti₂O₇:Yb³⁺, Er³⁺ phosphor decreases upon the 980 nm laser excitation. A novel upconversion luminescence temperature sensor was obtained by the intensity ratio of the upconversion luminescence of negative thermal expansion Y₂Mo₃O₁₂:Yb³⁺, Er³⁺ to the upconversion luminescence of positive thermal expansion Y₂Ti₂O₇:Yb³⁺, Er³⁺. The near infrared-red fluorescence intensity ratio (FIR) (I₈₆₀/I₆₇₅) was researched in the range from 293 K to 574 K, which suggests that FIR increases with rising temperature. The maximum relative sensitivity (S_r) was 1.61% K⁻¹ in near infrared-red FIR (I₈₆₀/I₆₇₅) at 293 K. The result suggests that the mixed phosphor exhibits potential application as a new temperature sensing device.