Promising Er³⁺/Yb³⁺-Codoped GdBiW₂O₉ Phosphor for Temperature Sensing by Upconversion Luminescence

Yb³⁺/Er³⁺-codoped GdBiW₂O₉ phosphors are prepared via the solid-state route for application in upconversion temperature sensors. The structural analyses indicate that all phosphors possess a single-phased orthorhombic structure. Upon the excitation of a laser wavelength of 980 nm, Yb³⁺/Er³⁺-codoped GdBiW₂O₉ phosphors emanate green emission peaks, endorsed to the emission to the ⁴I_15/2 state from the ⁴S_3/2 and ²H_11/2 states, respectively, and the weak emission (red) from the ⁴F_9/2 state to the ⁴I_15/2 state of Er³⁺ ion. The upconversion mechanism has been elucidated via the scheme of energy levels conferred from the pump power-induced upconversion characteristics. The temperature-dependent upconversion of GdBiW₂O₉ phosphors was investigated in detail along with the estimation of the stability and repeatability of the measurement. The obtained sensitivity data for the present materials with the corresponding sensing parameters show their probable outlook in temperature sensing applications.