Insight into temperature dependence of the photoluminescence properties of bright orange-red BaAl4Sb2O12:Bi3+ phosphors for fluorescence thermometry

Herein, a series of BaAl₄Sb₂O₁₂:Bi³⁺ phosphors (BASO:Bi³⁺) with desired orange-red emission were synthesized through a high-temperature solid-state reaction method. Under 365 nm excitation, an orange-red emission with the main peak at 598 nm and a full width at half maximum (FWHM) of 60 nm appeared, attributed to the transition from the ³P₁ → ¹S₀ energy level of Bi³⁺ ions. The emission intensity of BASO:xBi³⁺ (0.01 ≤ x ≤ 0.03) phosphors first increased along with Bi³⁺ doping and reached the maximum at x = 0.02 under excitation at 365 nm. Interestingly, the emission coefficient of the prepared phosphors is linearly related to temperature, and the intensity decreases sharply with increasing temperature. Bi³⁺-doped BASO host phosphors exhibit strong temperature-dependence within the range of 298 K to 473 K, and their activation energy is 0.30 eV for the thermal quenching mechanism. The temperature-dependent characteristics of luminescent materials doped with Bi³⁺ suggest that the maximum relative sensitivity of BASO:Bi³⁺ at 473 K is 2.59% K⁻¹, indicating that the sample is suitable for measurement in a wider temperature range. Under the co-doping of Bi³⁺/Eu³⁺, single-phase white light emission was achieved, and the CIE coordinates (0.3320, 0.3812) were extremely close to the standard white light coordinates. Thus, BaAl₄Sb₂O₁₂:Bi³⁺ phosphors show potential applications in optical temperature sensing fields.