Highly sensitive thermometry based on thermal quenching and negative thermal quenching materials

Suppose that the opposite changes of two emissions with temperature variation may result in a high sensitivity for a ratiometric thermometer; therefore, we design such a thermometer based on thermal quenching and negative thermal quenching materials. Herein, the Sc₂Mo₃O₁₂:Yb³⁺/Er³⁺ and Bi₂MoO₆:Yb³⁺/Tm³⁺ crystals are synthesized via the solid-state reaction, respectively, which have the properties of negative thermal expansion (NTE) and positive thermal expansion (PTE). The composite is obtained through simple mechanical mixing between NTE and PTE crystals, in which the Er³⁺ and Tm³⁺ luminescence exhibit enhancement and quenching with increasing temperature, respectively. Based on the fluorescence intensity ratio (FIR) technique, the maximum relative sensitivity of the thermometer is 3.80% K^-1 in the temperature range of 305-425 K. More importantly, the δT ≈ 0.24 K is relatively small meaning excellent accuracy. These findings indicate that the lanthanide-doped NTE and PTE composites may be good candidates for high sensitivity and accuracy thermometry.