The photoluminescence spectra and excitation spectra in the vacuum ultraviolet (VUV) and ultraviolet (UV) spectra region of GdVO 4∶Eu 3+ were reported. The excitation and emission spectra indicate that GdVO 4...The photoluminescence spectra and excitation spectra in the vacuum ultraviolet (VUV) and ultraviolet (UV) spectra region of GdVO 4∶Eu 3+ were reported. The excitation and emission spectra indicate that GdVO 4∶Eu 3+ is a highly efficient phosphor for the excitation in the VUV and UV spectrum region. The excitation band in the VUV and UV spectrum region of 60～350 nm consists mainly of the absorption of host, which has obvious absorption of 4f n-1 5d of Eu 3+ and Gd 3+ . In GdVO 4∶Eu 3+ , there is the energy transfer: VO 4 3- →Eu 3+ , Gd 3+ →Eu 3+ and Gd 3+ →VO 4 3- →Eu 3+ . Through the last two procedures, maybe the quantum cutting of Gd 3+ -Eu 3+ occurs.展开更多
Lutetium aluminum garnet （LuAG） precursors doped with different Pr^3＋ concentration （0.25at.%, 0.5at.%, 1.0at.%, 3.0at.%, 5.0at.%） were synthesized via a co-precipitation method using ammonium hydrogen carbonate ...Lutetium aluminum garnet （LuAG） precursors doped with different Pr^3＋ concentration （0.25at.%, 0.5at.%, 1.0at.%, 3.0at.%, 5.0at.%） were synthesized via a co-precipitation method using ammonium hydrogen carbonate as precipitant. The phase evolution and morphology of the precursor were characterized with X-ray diffractometer （XRD） and transmission electron microscopy （TEM）. The resultant LuAG：Pr^3＋ powder was sintered into translucent ceramic without any additives in vacuum at 1150 ℃ and then in nitrogen atmosphere at 1700 ℃. spectra of LuAG：Pr^3＋ powder and ceramic were measured at room temperature in vacuum ultraviolet （VUV） and ultraviolet （VU） region. For the 5d-4f transition of Pr^3＋ ions, dominant emission of ceramic samples peaking round 311 um had higher luminescence intensity. And the host absorption in ceramic samples was not as intensive as that in powder samples. The luminescent intensity of LuAG：Pr^3＋ varied with the Pr^3＋ contents and the quenching concentration was about 1.0at.% for ceramic and 3.0at.% for powder, which was much higher than 0.24at.% for LuAG：Pr^3＋ single crystals. This phenomenon showed that the ceramic had some superiority over single crystals.展开更多
The degradation of atrazine (ATZ),sulfamethoxazole (SMX) and metoprolol (MET) in flowthrough VUV/UV/H2O2reactors was investigated with a focus on the effects of H2O2dosage and reactor internal diameter (ID).Results sh...The degradation of atrazine (ATZ),sulfamethoxazole (SMX) and metoprolol (MET) in flowthrough VUV/UV/H2O2reactors was investigated with a focus on the effects of H2O2dosage and reactor internal diameter (ID).Results showed that the micropollutants were degraded efficiently in the flow-through VUV/UV/H2O2reactors following the pseudo first-order kinetics (R2>0.92).However,the steady-state assumption (SSA) kinetic model being vital in batch reactors was found invalid in flow-through reactors where fluid mixing was less sufficient.With the increase of H2O2dosage,the ATZ removal efficiency remained almost constant while the SMX and MET removal was enhanced to different extents,which could be explained by the different reactivities of the pollutants towards HO·.A larger reactor ID resulted in lower degradation rate constants for all the three pollutants on account of the lower average fluence rate,but the change in energy efficiency was much more complicated.In reality,the electrical energy per order (EEO) of the investigated VUV/UV/H2O2treatments ranged between 0.14–0.20,0.07–0.14 and 0.09–0.26 k Wh/m3/order for ATZ,SMX and MET,respectively,with the lowest EEOfor each pollutant obtained under varied H2O2dosages and reactor IDs.This study has demonstrated the efficiency of VUV/UV/H2O2process for micropollutant removal and the inadequacy of the SSA model in flow-through reactors,and elaborated the influential mechanisms of H2O2dosage and reactor ID on the reactor performances.展开更多
文摘The photoluminescence spectra and excitation spectra in the vacuum ultraviolet (VUV) and ultraviolet (UV) spectra region of GdVO 4∶Eu 3+ were reported. The excitation and emission spectra indicate that GdVO 4∶Eu 3+ is a highly efficient phosphor for the excitation in the VUV and UV spectrum region. The excitation band in the VUV and UV spectrum region of 60～350 nm consists mainly of the absorption of host, which has obvious absorption of 4f n-1 5d of Eu 3+ and Gd 3+ . In GdVO 4∶Eu 3+ , there is the energy transfer: VO 4 3- →Eu 3+ , Gd 3+ →Eu 3+ and Gd 3+ →VO 4 3- →Eu 3+ . Through the last two procedures, maybe the quantum cutting of Gd 3+ -Eu 3+ occurs.
基金supported by the National Natural Science Foundation of China (10774140)Funds for International Cooperation and Exchange of the National Nature Science Foundation of China (50711120504)+1 种基金Specialized Research Fund for the Doctoral Program of Higher Education (20060358054)Special Foundation for Talents of Anhui Province, China (2007Z021)
文摘Lutetium aluminum garnet （LuAG） precursors doped with different Pr^3＋ concentration （0.25at.%, 0.5at.%, 1.0at.%, 3.0at.%, 5.0at.%） were synthesized via a co-precipitation method using ammonium hydrogen carbonate as precipitant. The phase evolution and morphology of the precursor were characterized with X-ray diffractometer （XRD） and transmission electron microscopy （TEM）. The resultant LuAG：Pr^3＋ powder was sintered into translucent ceramic without any additives in vacuum at 1150 ℃ and then in nitrogen atmosphere at 1700 ℃. spectra of LuAG：Pr^3＋ powder and ceramic were measured at room temperature in vacuum ultraviolet （VUV） and ultraviolet （VU） region. For the 5d-4f transition of Pr^3＋ ions, dominant emission of ceramic samples peaking round 311 um had higher luminescence intensity. And the host absorption in ceramic samples was not as intensive as that in powder samples. The luminescent intensity of LuAG：Pr^3＋ varied with the Pr^3＋ contents and the quenching concentration was about 1.0at.% for ceramic and 3.0at.% for powder, which was much higher than 0.24at.% for LuAG：Pr^3＋ single crystals. This phenomenon showed that the ceramic had some superiority over single crystals.
基金supported by the National Natural Science Foundation of China(No.51908536)the Ministry of Science and Technology of China(No.2018YFE0204103)。
文摘The degradation of atrazine (ATZ),sulfamethoxazole (SMX) and metoprolol (MET) in flowthrough VUV/UV/H2O2reactors was investigated with a focus on the effects of H2O2dosage and reactor internal diameter (ID).Results showed that the micropollutants were degraded efficiently in the flow-through VUV/UV/H2O2reactors following the pseudo first-order kinetics (R2>0.92).However,the steady-state assumption (SSA) kinetic model being vital in batch reactors was found invalid in flow-through reactors where fluid mixing was less sufficient.With the increase of H2O2dosage,the ATZ removal efficiency remained almost constant while the SMX and MET removal was enhanced to different extents,which could be explained by the different reactivities of the pollutants towards HO·.A larger reactor ID resulted in lower degradation rate constants for all the three pollutants on account of the lower average fluence rate,but the change in energy efficiency was much more complicated.In reality,the electrical energy per order (EEO) of the investigated VUV/UV/H2O2treatments ranged between 0.14–0.20,0.07–0.14 and 0.09–0.26 k Wh/m3/order for ATZ,SMX and MET,respectively,with the lowest EEOfor each pollutant obtained under varied H2O2dosages and reactor IDs.This study has demonstrated the efficiency of VUV/UV/H2O2process for micropollutant removal and the inadequacy of the SSA model in flow-through reactors,and elaborated the influential mechanisms of H2O2dosage and reactor ID on the reactor performances.
