Wang Lejian, Zhang Jingji, Wang Jiangying, Yao Yaxuan, Ren Lingling, Chen Xue, Birkett Martin, Dala Laurent, Xu Ben
Opt Lett. 2020 Apr 15;45(8):2391-2394. doi: 10.1364/OL.391422.
A novel lead-free luminescent ferroelectric (FE) ceramic, ${{\rm Bi}{0.5}}{{\rm Na}{0.5}}{{\rm TiO}3} {-} {0.{06; \rm BaTiO}3} {-} {0.{055;\rm Sr}{0.7}}{{\rm Bi}{0.18}}{{\rm Er}{0.02 ,\square, 0.1}}$BiNaTiO-0.06BaTiO-0.055SrBiEr${{\rm TiO}3}$TiO (BNT-BT-SBET), is developed with an adiabatic temperature change ($\Delta T$ΔT) of 0.7 K under an electric field ($E$E) of 60 kV/cm at room temperature, an anti-Stokes fluorescence cooling, and a maximum optical $T$T sensitivity of ${0.0055};{{\rm K}^{ - 1}}$0.0055K at 522 K. Interestingly, the electrocaloric response reaches a saturation at permittivity shoulder $T$T of 100°C; meanwhile, the maximized emission intensity of $^2{{\rm H}{11/2}}{ \to ^4}{{\rm I}{15/2}}$H→I occurs. $T$T- and $E$E-tunable enhancement of $^2{{\rm H}{11/2}}{ \to ^4}{{\rm I}{15/2}}$H→I emission intensity is due to the population inversion from the $^4{{\rm S}{3/2}}$S to $^2{{\rm H}{11/2}}$H states caused by an incoherent regime consisting of FE phase and polar nanoregions in a relaxor matrix.
