Splendid cryogenic optical thermometry and rewritable photomemory based on the up-conversion luminescence of K0.5Bi0.5TiO3: Er/In ceramic

Abstract

Bifunctional luminescence materials have aroused considerable concern due to their wide application and high utilization. In this study, we have successfully integrated bright green up-conversion luminescence of K_0.5Bi_0.5TiO₃ (KBT): Er/In ceramics with potential applications on cryogenic optical thermometry and photomemory. By employing the fluorescence intensity ratio based on thermally coupled levels of Er³⁺: ²H_11/2/⁴S_3/2, the splendid low-temperature sensing properties were demonstrated as the maximum relative sensitivities were 7.14% K⁻¹ and 8.73% K⁻¹ at 137 K for KBT: Er and KBT: Er/In ceramics, respectively. Moreover, the reversible photochromism performance could be triggered by the 365 nm irradiation and vanished by thermal stimulation at 150 °C. Remarkably, the coupling of up-conversion luminescence and photochromism performance has a promising application on rewritable photomemory. For the KBT: Er/In ceramic, the emission intensity could be reduced by 76.59% after coloration, and restored to its original value after bleaching. In order to evaluate the practicability of applying on photomemory, a reversible experiment was designed and successfully executed. It is believed that the KBT: Er/In bifunctional ceramic can be a great candidate for low-temperature sensing and optical information storage devices.