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Enhanced photoluminescence and ultrahigh temperature sensitivity from NaF flux assisted CaTiO3: Pr3+ red emitting phosphor
摘要： The Pr3+ doped CaTiO3 red emitting phosphor with enhanced PL and ultrahigh temperature sensing was prepared via NaF flux assisted solid-state reaction. All samples had the orthorhombic perovskite phase and no impurity was found. The typical sample mainly had sphere-like morphology with particle size of ~670 nm. The optical bandgap values were ~3.62-3.63eV. The Pr3+ quenching content was 0.6 mol% and the ET mechanism for quenching was the d-d interaction with the critical distance of 26.09 ?. A certain amount of NaF flux could enhance red emission attributed to 1D2→3H4 transition owing to improving the crystallinity of phosphors and reducing point defects near Pr3+ through the substitution of O2- by F- and Ca2+ by Na+. The energy storage trap (oxygen vacancy) near IVCT state played the key role for trapping electrons, accounting for the LAG emission and the average depth of trap was 0.39 eV. The CIE chromaticity coordinates were very close to that of the ideal red light and the CP was as high as 99.98%. The maximal Sa and Sr was as high as ~0.015 K-1 and~ 5.2% K-1, respectively. The thermal induced relaxation between the 3Pj levels and 1D2 level through the IVCT state was supposed to account for the excellent optical temperature sensing. Our work may provide a useful inspiration for developing ultrahigh sensitive optical temperature sensors.
关键词： Praseodymium,Calcium titanate,Optical thermometry,Intervalence charge transfer state
更新于2025-09-23 15:23:52
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CaTiO3:Er3+:Yb3+ Upconversion from 980 nm and 1550 nm Excitation and its Potential as Cells Luminescent Probes
摘要： CaTiO3:xEr3+:yYb3+ (x = 0.3mol%; y = 1.0, 1.5 and 2.0 mol%) was synthesized by the sol-gel process. Crystal phase purity, crystallite sizes and microstrain were evaluated as a function of rare earths concentration through XRD and SEM techniques. Upconversion (UC) spectra were recorded at 300 K under excitation at 980 nm and 1550 nm. The samples showed higher intensity of green emission assigned to the upconversion phenomena compared to the red one, when excited at 980 nm and the opposite was observed when excitation was performed at 1550 nm. The nanoparticles CaTiO3:Er3+:Yb3+ were successfully applied as animals cells cytoplasm staining luminescent probes, with low cytotoxic effect being observed. Er3+ emission at 1550 nm was also proposed for in vitro or in vivo optical imaging analysis in the so-called second window (1350 - 2300 nm).
关键词： ytterbium,calcium titanate,erbium,fluorescent cell dyeing,upconversion
更新于2025-09-10 09:29:36