Tailoring of upconversion luminescence of Al³⁺engineered titanate phosphor for non-invasive thermometry

The ability of rare-earth-doped ferroelectric oxides to achieve outstanding upconversion (UC) performances under NIR irradiation despite possessing intrinsic electric properties drives researchers all over the globe to work in this field. The structural and spectroscopic characteristics of the Bi₄Ti₃O₁₂phosphor integrated with Er³⁺, Yb³⁺, and Al³⁺have been thoroughly investigated in this study. The considerable increase in UC emission ∼three times caused by the addition of Al³⁺ions has been observed and discussed. The processes connected with the UC emission related to the pump power variation have been realized using the rate law equation. Aside from having high sensitivity of 0.011 K^-1at room temperature, the prepared phosphor possesses excellent thermal stability, i.e., it retains ∼73% of its initial intensity with the addition of Al³⁺ions.