A high-performance temperature-sensing luminescent material of Ni²⁺-doped double perovskite structure Li₂TiTeO₆...

A series of Ni²⁺-doped Li₂TiTeO₆ (LTTO) phosphors were successfully synthesized by a high-temperature solid-state method. The crystal structure, luminescence characteristics and temperature sensing performance of the phosphors were systematically studied. Under 380 nm excitation, the phosphor emits near-infrared light in the wavelength range of 1200-1700 nm, with a main emission peak at 1450 nm, a full-width at half-maximum (FWHM) of 233 nm (∼1115 cm^-1), and the optimum Ni²⁺ doping concentration of x = 0.003. The temperature-dependent emission spectra and fluorescence lifetime measurements demonstrated that the LTTO:0.003Ni²⁺ phosphor exhibits pronounced temperature-dependent behavior within the 223-348 K range. The maximum relative sensitivity (S_r) and absolute sensitivity (S_a) of the phosphors are 6.83% K^-1 (348 K) and 0.176 μs K^-1 (300 K), respectively, substantially outperforming most previously reported Ni²⁺-doped optical thermometric phosphors. These findings indicate that LTTO:Ni²⁺ phosphors possess great potential for application in non-contact, high-precision optical thermometry.