Electrical properties improvement and excellent upconversion luminescence of PSMHYT crystals

A novel Pb(Sc1/2Nb1/2)O3-Pb(Mg1/3Nb2/3)O3-Pb(Ho1/2Nb1/2)O3-Pb(Yb1/2Nb1/2)O3-PbTiO3 (PSMHYT) crystal was grown by using the flux method. XRD and Raman scattering determined pure perovskite structure of as-grown crystals. Electrical test results showed that the crystal along [100]-orientation was of high Curie temperature Tc (192 °C), large coercive field Ec (15.90 kV/cm) and remanent polarization Pr (31.94 μC/cm2), which were higher than those of most crystals reported previously. The optical absorption at UV-VIS-NIR bands related to Ho3+ and Yb3+ was observed. Irradiated by excitation sources with different wavelengths (245, 460 and 980 nm), weak downconversion (DC) and strong upconversion (UC) luminescences were achieved, and related UC emission mechanism was also analyzed. Rich luminescence was ascribed to abundant energy levels of rare earth Ho3+. Furthermore, focused on the up-conversion process, the fluorescence lifetime (τ) from 5F4/5S2→5I8 (green) transition and total quantum yield in green and red emissions were investigated, with results of 0.1/0.039 ms and 0.39% obtained. Excellent electrical and optical properties make PSMHYT crystal a promising substitute material in transducers, sensors, and optoelectronic coupling devices.