Green Up‐Conversion Photoluminescence and Dielectric Relaxation of Ho3+/Yb3+‐Codoped Bi2Ti2O7 Pyrochlore Thin Films |
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Authors: | Jianxiong Zhao Ni Qin Dinghua Bao |
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Affiliation: | State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat‐Sen University, , Guangzhou, 510275 China |
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Abstract: | Ho3+/Yb3+‐codoped Bi2Ti2O7 pyrochlore thin films were prepared by a chemical solution deposition method, and their visible up‐conversion (UC) photoluminescence and dielectric relaxation were studied. Ho and Yb can be doped into Bi2Ti2O7 lattice and single pyrochlore phase is maintained. Intense visible UC photoluminescence can be observed under the excitation of a 980‐nm diode laser. Two UC emission bands centered at 551 nm and 665 nm in the spectra can be assigned to 5F4, 5S2→5I8 and 5F5→5I8 transitions of Ho3+ ions, respectively. The dependence of their UC emission intensity on pumping power indicates that both the green and red emissions of the thin films are two‐photon process. In addition, a Stokes near‐infrared emission centered at 1200 nm can be detected, which is due to 5I6→5I8 transition of Ho3+ ions. The thin films prepared on indium tin oxide–coated glass substrates exhibit a relatively high dielectric constant and a low dielectric loss as well as a good bias voltage stability. The dielectric relaxation of the thin films was also analyzed based on the temperature‐ and frequency‐dependent dielectric properties. This study suggests that Ho3+/Yb3+‐codoped Bi2Ti2O7 thin films are promising materials for developing multifunctional optoelectronic thin film devices. |
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