Blue and near-infrared up-conversion photoluminescence and dielectric relaxation of Tm3+/Yb3+ co-doped (Bi, Y)2Ti2O7 pyrochlore thin films

The blue emission and near-infrared (NIR) up-conversion photoluminescence and dielectric relaxation of Tm3+/Yb3+ co-doped (Bi, Y)2Ti2O7 pyrochlore thin films prepared by a chemical solution deposition method have been investigated. The pyrochlore phase has been maintained for all compositions. Intense blue and NIR emission can be detected on the thin films on fused silica substrates excited by a 980 nm diode laser. Three UC emission bands centered at 480 nm, 665 nm, and 800 nm in the spectra can be assigned to 1G4→3H6, 1G4→3F4 and 3H4→3H6 transitions of Tm3+ ions, respectively. The dependence of UC emission intensity on pumping power indicates that the blue emission of the thin films follows a three-photon process while the NIR emission is a two-photon process. The thin films also exhibit a relatively high dielectric constant and a low loss as well as good bias voltage stability. Temperature and frequency dependent dielectric relaxation has been investigated. This study suggests that Tm3+/Yb3+ co-doped (Bi, Y)2Ti2O7 thin films can be applied to new multifunctional photoluminescence dielectric thin-film devices.