Structural analysis and optical temperature sensing performance of Eu3+-doped Ba3In(PO4)3

Abstract

Eu³⁺-Doped Ba₃In(PO₄)₃ was synthesized through a high-temperature solid-phase method. According to the structure refinement based on X-ray diffraction and density functional theory, the crystal and energy band structures of Ba₃In_(1−x)(PO₄)₃:xEu³⁺ were studied and analyzed in detail. The effect of Eu³⁺ doping concentrations on emission was studied at an excitation wavelength of 393 nm. For the material Ba₃In_(1−x)(PO₄)₃:xEu³⁺(x = 0.01–0.30), the optimal doping level is confirmed to be 0.18. Due to the thermal quenching differences of Eu³⁺ at the ⁵D₀ and ⁵D₁ energy levels, and based on the temperature-variable fluorescence intensity ratio between emission peaks, the optical temperature measurement performance of this material in the temperature range from 298.15 K to 623.15 K was characterized, and the maximum absolute and relative sensor sensitivities (S_a and S_r) were determined to be 0.1002 K⁻¹ and 4.058%, respectively. With temperature as the only variable, the color of the phosphor changes from red to yellow light with rising temperature. Besides, S_a and S_r values of this phosphor are comparable to other sensing materials. The results indicate that Eu³⁺-doped Ba₃In(PO₄)₃ phosphors have great potential to be applied in optical temperature sensing.