Multiple lattice sites occupied AlTaO4:Cr3+ phosphor for luminescence ratiometric thermometry and NIR light source

Cr3+-doped near infrared (NIR) phosphors have promising applications in NIR light sources and optical temperature detection. The development of materials with high relative sensitivity and efficient broadband NIR luminescence is the key. In this paper, we report a new multifunctional NIR phosphor AlTaO4:Cr3+, which contains both narrow-band emission associated with 2Eg→4A2 g transition and broadband emission induced by the 4T2 g→4A2 g transition owing to Cr3+ occupies both AlO6 and TaO6 lattice sites. The R-line (2Eg→4A2 g) emission and its anti-Stokes phonon sideband emission follow the Boltzmann distribution, and the thermometer constructed accordingly reaches a maximum Sr of 1% K−1 at 110 K. Under 425 nm excitation, the broad emission band (FWHM = 200 nm) reaches maximum at 880 nm with an internal quantum efficiency of 62.8%. The NIR LEDs prepared with AlTaO4:Cr3+ confirm the application value in NIR light sources. [Display omitted] •A multiple lattice sites occupied AlTaO4:Cr3+ phosphor is reported.•AlTaO4:Cr3+ phosphor can be used for both luminescence ratiometric thermometry and NIR lighting.•The constructed LIR thermometer shows a highly sensitive (1% K−1 @110 K).•The AlTaO4:Cr3+ shows a broadband emission (FWHM=200 nm) at 880 nm and an IQE of 62.8%.