Effects of temperature and electric field on upconversion luminescence in Er3+-Yb3+ codoped Ba0.8Sr0.2TiO3 ferroelectric ceramics

Optical and electrical properties of 1% Er3+ and different Yb3+ content (1ExY) codoped Ba0.8Sr0.2TiO3 (BST) ferroelectric ceramics fabricated by the solid-phase reaction were investigated. Under 980 nm pump condition, two green emission bands at 525 and 549 nm wavelength corresponding to, H-2(11/2) -> I-4(15/2) and S-2(3/2) -> I-4(15/2) transitions, and two red emission bands at 655 and 668 nm wavelength attributed to F-4(9/2) -> I-4(15/2) transition are observed. The temperature-sensing behaviors, calculated by the intensity ratio I-525/I-549 suggested that, the maximum sensitivity of the green emission of the 1E8Y-BST ceramics is 1.07 x 10(-2) K-1 at 293 K. Furthermore, the maximum sensitivity of 1E6Y-BST and 1E11Y-BST ceramics were obtained around the Curie temperature. The fluorescence lifetime of 1E8Y-BST ceramics for H-2(11/2) level and S-2(3/2) level shortened with the increase in the temperatures. Moreover, the upconversion (UC) luminescence intensity of 1E8Y-BST decreased with the increase in the external electric field and had a mutation at the coercive electric field (E-c) of about 1.24 kV/cm, which revealed that the electric field had influence on the UC luminescence.