The phosphors of （Bi1- x Smx ） 2ZnB2O7 （ x = 0. 01, 0. 03, 0. 05, 0. 07, and 0. 09） were synthesized by conventional solid state reaction. The purity of all samples was checked by X-ray powder diffraction （XRD）....The phosphors of （Bi1- x Smx ） 2ZnB2O7 （ x = 0. 01, 0. 03, 0. 05, 0. 07, and 0. 09） were synthesized by conventional solid state reaction. The purity of all samples was checked by X-ray powder diffraction （XRD）. XRD analysis shows that all these compounds are of a single phase of Bi2ZnB2O7, indicating that the Bi^3＋ in Bi2ZnB2O7 can be partly replaced by the Sm^3＋ without the change of crystal structure. The excitation and emission spectra at room temperature show the typical 4f-4f transitions of Sm^3＋ . The dominant excitation line is around 404 nm due to ^6H5/2→^4K11/2 and the emission spectrum consists of a series of lines at 563, 599, 646, and 704 nm due to ^4G5/2→^6H5/2, ^6H7/2, ^6H9/2, and ^6H11/2, respectively. The optimal concentration of Sm^3＋ in Bi2ZnB2O7 is about 3mol% （relative to lmol Bi^3＋ ） and the critical distance Rc was calculated as 2.1 nm. The temperature dependence of the emission intensity of Bi1.94Sm0.06ZnB2O7 was examined in the temperature range between 100 and 450 K. The quenching temperature where the intensity has dropped to half of the initial intensity is 280 K. The lifetime for Sm^3＋ in Bi1.94Sm0.06ZnB2O7 is fitted as a value of 0.29 and 1.03 ms.展开更多
Oxyfluoride glasses were developed with composition 60GeO 2 ·10AlF 3 ·25BaF 2 ·（1.95-x）GdF 3 · 3YbF 3 ·0.05TmF 3 ·xErF 3 （x=0.02,0.05,0.08,0.11,0.14,0.17）in mole percent.Intense blue...Oxyfluoride glasses were developed with composition 60GeO 2 ·10AlF 3 ·25BaF 2 ·（1.95-x）GdF 3 · 3YbF 3 ·0.05TmF 3 ·xErF 3 （x=0.02,0.05,0.08,0.11,0.14,0.17）in mole percent.Intense blue（476 nm）,green（524 and 546 nm）and red（658 nm）emissions which identified from the 1G 4 →3H 6 transition of Tm3＋and the（2H 11/2 ,4S 3/2 ）→4I 15/2 ,4F 9/2 →4I 15/2 transitions of Er3＋,respectively,were simultaneously observed under 980 nm excitation at room temperature.The results show that multicolor luminescence including white light can be adjustably tuned by changing doping concentrations of Er3＋ion or the excitation power.In addition,the energy transfer processes among Tm3＋,Er3＋and Yb3＋ions,and up-conversion mechanisms are discussed.展开更多
Exploring low-cost and high-performance catalysts for oxygen evolution reaction(OER)remains to be a great challenge.Iridium-based perovskite oxide has large potential in OER because of its intrinsic activity and outst...Exploring low-cost and high-performance catalysts for oxygen evolution reaction(OER)remains to be a great challenge.Iridium-based perovskite oxide has large potential in OER because of its intrinsic activity and outstanding physicochemical properties.In this study,iridium-doped strontium titanate(Ir-STO)solution is brushed on a Ti sheet by the traditional method to obtain the Ir-STO/Ti electrodes after being calcined at a high temperature.The microstructure and electrocatalysis properties of the Ir-STO are further modified by a facile and scalable NH_(3)-plasma strategy.In addition to the doping of Ir,the NH_(3) plasma treatment further results in N-doping into Ir-STO,which enriches active species and causes oxygen vacancies near doped sites.The resulting N,Ir-STO/Ti electrode reveals excellent acidic OER activity with the lowest overpotential of 390 m V at 10 m A/cm^(2) and the smallest Tafel slope of 140 mV/dec after 10-min plasma treatment.Therefore,the great potential of activated N,Ir-STO/Ti is regarded as a catalyst for the OER,and thus making a new opportunity for developing other perovskite catalysts via NH_(3) plasma treatment.展开更多
A series of SrIn2 O4 ：Eu^3＋ phosphors are synthesized by a high temperature solid-state method, and their luminescent properties are investigated. They can be excited by 395-nm radiation, and produce red emission （...A series of SrIn2 O4 ：Eu^3＋ phosphors are synthesized by a high temperature solid-state method, and their luminescent properties are investigated. They can be excited by 395-nm radiation, and produce red emission （619 nm）; however, they have a low absorption of near-ultraviolet light with the wavelength of 400nm–405 nm. When co-doped with A^＋ （A=Li, Na, K）, the emission intensity of SrIn2O4 ：Eu^3＋ is significantly enhanced, but its emission and excitation spectral profile is unchanged. With co-doping Sm^3＋ , not only is the emission intensity of SrIn2 O4 ：Eu^3＋ enhanced, but also the absorption is broadened and strengthened in the range of 400 nm–405nm. The effect of Sm^3＋ -doped content on the emission intensity of SrIn2O4 ：Eu^3＋ , Sm^3＋ is investigated, and the optimal Sm^3＋ content is 0.02 mol.展开更多
The Sm^（3＋）-doped SrO-Al2O3-SiO2（SAS） glass-ceramics with excellent luminescence properties were prepared by batch melting and heat treatment. The crystallization behavior and luminescent properties of the glass-...The Sm^（3＋）-doped SrO-Al2O3-SiO2（SAS） glass-ceramics with excellent luminescence properties were prepared by batch melting and heat treatment. The crystallization behavior and luminescent properties of the glass-ceramics were investigated by DTA, XRD, SEM and luminescence spectroscopy. The results indicate that the crystal phase precipitated in this system is monocelsian（SrAl2Si2O） and with the increase of nucleation/crystallization temperature, the crystallite increases from 66 % to 79 %. The Sm（3＋）-doped SAS glass-ceramics emit green, orange and red lights centered at 565, 605, 650 and 715 nm under the excitation of 475 nm blue light which can be assigned to the 4 G5/2→6 Hj/2（j=5, 7, 9, 11） transitions ofSm^（3＋）, respectively. Besides, by increasing the crystallization temperature or the concentration ofSm^（3＋）, the emission lights of the samples located at 565, 605 and 650 nm are intensified significantly. The present results demonstrate that theSm^（3＋）-doped SAS glassceramics are promising luminescence materials for white LED devices by fine controlling and combining of these three green, orange and red lights in appropriate proportion.展开更多
Erbium-doped BaTiO3 films on LaNiO3/Si substrates were fabricated by sol-gel method. The crystalline structure, morphologies and upconversion （UC） luminescence properties of films were respectively investigated by X...Erbium-doped BaTiO3 films on LaNiO3/Si substrates were fabricated by sol-gel method. The crystalline structure, morphologies and upconversion （UC） luminescence properties of films were respectively investigated by X-ray diffraction （XRD）, atomic force microcopy （AFM） and photoluminescence （PL）. The results indicate that both of the microstructure and luminescence are found to be dependent on Er^3＋ substituting sites. The samples with A-site substitution have smaller lattice constants, larger grains and smoother surface than those with B-site substitution. The photoluminescence spectra show that both of the samples have two stronger green emission bands centered at 528 and 548 nm and a weak red emission band centered at 673 nm, which correspond to the relaxation of Er^3＋ from ^2H11/2, ^4S3/2, and ^4F9/2 levels to the ground level ^4I15/2, respectively. Compared with B-site doped films, A-site doped films have a stronger integrated intensity of green emissions and a weaker relative intensity of red emissions. The differences could be explained by the crystalline quality and cross relaxation （CR） process.展开更多
A series of Zr-doped CaTiO3 powders were prepared with the mild co-precipitation method and calcined at 850℃ for 3 h. The as-prepared Zr-doped CaTiO3 samples were characterized by scanning electron microscopy （SEM）...A series of Zr-doped CaTiO3 powders were prepared with the mild co-precipitation method and calcined at 850℃ for 3 h. The as-prepared Zr-doped CaTiO3 samples were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, UV-Vis diffuse reflectance spectra （DRS） and X-ray photoelectron spectra （XPS）. XRD result revealed the presence of single perovskite phase of CaTiO3. UV-Vis diffusive reflection spectra of Zr-doped CaTiO3 indicated that the absorbance obviously increased in the visible light irradiation. XPS analysis showed that two types of oxygen existed on the photocatalyst surface, including lattice oxygen and absorbed oxygen. Their photocatalytic activity in the case of the degradation of methyl orange in water and photoelectrochemical activity were also tested. The 5%Zr-doped （mole fraction） CaTiO3 sample showed the highest photocatalytic activity. The enhanced photocatalytic activity was ascribed to the change of the lattice structure, existence of oxygen vacancies and increase of the photogenerated charge separation efficiency.展开更多
Fe^3＋ -doped nanometer TiO2 photocatalysts were prepared by sol-gel technique. TiO2 powders with different Fe^3＋ / Ti^4 ＋ molar ratios ranging from 0. 05% to 25% were synthesized by calcinating the gels in the temp...Fe^3＋ -doped nanometer TiO2 photocatalysts were prepared by sol-gel technique. TiO2 powders with different Fe^3＋ / Ti^4 ＋ molar ratios ranging from 0. 05% to 25% were synthesized by calcinating the gels in the temperature range of 200-600 ℃ . The effects of the content of iron ions and calcination temperature on the physical properties of the powders and their photocatalytic activities were examined by the photodecorapositon of methyl orange in sunlight. The results show that Fe dopant can decrease the temperature of nanatase-ratile transformation. The ideal photocatalytic property was achieved when the sample with an Fe^3＋ / Ti^4＋ ratio of 20 at% was calcined at about 300 ℃ for an hour, which is superior to that of commercial Degussa P-25. The optimum microstructure of the Fe-doped TiO2 for a high photocatalytic activity in sunlight is consisted of nanatase and ratile.展开更多
基金Project supported by the National Natural Science Foundation of China (20501023) and the Guangdong Provincial NaturalScience Foundation (5300527)
文摘The phosphors of （Bi1- x Smx ） 2ZnB2O7 （ x = 0. 01, 0. 03, 0. 05, 0. 07, and 0. 09） were synthesized by conventional solid state reaction. The purity of all samples was checked by X-ray powder diffraction （XRD）. XRD analysis shows that all these compounds are of a single phase of Bi2ZnB2O7, indicating that the Bi^3＋ in Bi2ZnB2O7 can be partly replaced by the Sm^3＋ without the change of crystal structure. The excitation and emission spectra at room temperature show the typical 4f-4f transitions of Sm^3＋ . The dominant excitation line is around 404 nm due to ^6H5/2→^4K11/2 and the emission spectrum consists of a series of lines at 563, 599, 646, and 704 nm due to ^4G5/2→^6H5/2, ^6H7/2, ^6H9/2, and ^6H11/2, respectively. The optimal concentration of Sm^3＋ in Bi2ZnB2O7 is about 3mol% （relative to lmol Bi^3＋ ） and the critical distance Rc was calculated as 2.1 nm. The temperature dependence of the emission intensity of Bi1.94Sm0.06ZnB2O7 was examined in the temperature range between 100 and 450 K. The quenching temperature where the intensity has dropped to half of the initial intensity is 280 K. The lifetime for Sm^3＋ in Bi1.94Sm0.06ZnB2O7 is fitted as a value of 0.29 and 1.03 ms.
基金Funded by the National Natural Science Foundation of China (No. 50772045)the Society Development Foundation of Yunnan Province (No. 2007E036M)
文摘Oxyfluoride glasses were developed with composition 60GeO 2 ·10AlF 3 ·25BaF 2 ·（1.95-x）GdF 3 · 3YbF 3 ·0.05TmF 3 ·xErF 3 （x=0.02,0.05,0.08,0.11,0.14,0.17）in mole percent.Intense blue（476 nm）,green（524 and 546 nm）and red（658 nm）emissions which identified from the 1G 4 →3H 6 transition of Tm3＋and the（2H 11/2 ,4S 3/2 ）→4I 15/2 ,4F 9/2 →4I 15/2 transitions of Er3＋,respectively,were simultaneously observed under 980 nm excitation at room temperature.The results show that multicolor luminescence including white light can be adjustably tuned by changing doping concentrations of Er3＋ion or the excitation power.In addition,the energy transfer processes among Tm3＋,Er3＋and Yb3＋ions,and up-conversion mechanisms are discussed.
基金Project supported by the Priority Academic Program Development(PAPD)Program of Jiangsu Higher Education Institutions,Jiangsu Province,Chinathe National Natural Science Foundation of China(Grant No.11675117)。
文摘Exploring low-cost and high-performance catalysts for oxygen evolution reaction(OER)remains to be a great challenge.Iridium-based perovskite oxide has large potential in OER because of its intrinsic activity and outstanding physicochemical properties.In this study,iridium-doped strontium titanate(Ir-STO)solution is brushed on a Ti sheet by the traditional method to obtain the Ir-STO/Ti electrodes after being calcined at a high temperature.The microstructure and electrocatalysis properties of the Ir-STO are further modified by a facile and scalable NH_(3)-plasma strategy.In addition to the doping of Ir,the NH_(3) plasma treatment further results in N-doping into Ir-STO,which enriches active species and causes oxygen vacancies near doped sites.The resulting N,Ir-STO/Ti electrode reveals excellent acidic OER activity with the lowest overpotential of 390 m V at 10 m A/cm^(2) and the smallest Tafel slope of 140 mV/dec after 10-min plasma treatment.Therefore,the great potential of activated N,Ir-STO/Ti is regarded as a catalyst for the OER,and thus making a new opportunity for developing other perovskite catalysts via NH_(3) plasma treatment.
基金Project supported by the National Natural Science Foundation of China (Grant No. 50902042)the Natural Science Foundation of Hebei Province, China(Grant Nos. E2009000209 and E2010000283)+1 种基金the Education Bureau Foundation of Hebei Province, China (Grant No. 2009313)the Key Laboratory of Luminescence and Optical Information, Beijing Jiaotong University, Ministry of Education, China (Grant No. 2010LOI12)
文摘A series of SrIn2 O4 ：Eu^3＋ phosphors are synthesized by a high temperature solid-state method, and their luminescent properties are investigated. They can be excited by 395-nm radiation, and produce red emission （619 nm）; however, they have a low absorption of near-ultraviolet light with the wavelength of 400nm–405 nm. When co-doped with A^＋ （A=Li, Na, K）, the emission intensity of SrIn2O4 ：Eu^3＋ is significantly enhanced, but its emission and excitation spectral profile is unchanged. With co-doping Sm^3＋ , not only is the emission intensity of SrIn2 O4 ：Eu^3＋ enhanced, but also the absorption is broadened and strengthened in the range of 400 nm–405nm. The effect of Sm^3＋ -doped content on the emission intensity of SrIn2O4 ：Eu^3＋ , Sm^3＋ is investigated, and the optimal Sm^3＋ content is 0.02 mol.
基金Funded by the National Natural Science Foundation of China(No.5137217)Hubei Province Foreign Science and Technology Project(No.2016AHB027)Science and Technology Planning Project of Hubei Province(No.2014BAA136)
文摘The Sm^（3＋）-doped SrO-Al2O3-SiO2（SAS） glass-ceramics with excellent luminescence properties were prepared by batch melting and heat treatment. The crystallization behavior and luminescent properties of the glass-ceramics were investigated by DTA, XRD, SEM and luminescence spectroscopy. The results indicate that the crystal phase precipitated in this system is monocelsian（SrAl2Si2O） and with the increase of nucleation/crystallization temperature, the crystallite increases from 66 % to 79 %. The Sm（3＋）-doped SAS glass-ceramics emit green, orange and red lights centered at 565, 605, 650 and 715 nm under the excitation of 475 nm blue light which can be assigned to the 4 G5/2→6 Hj/2（j=5, 7, 9, 11） transitions ofSm^（3＋）, respectively. Besides, by increasing the crystallization temperature or the concentration ofSm^（3＋）, the emission lights of the samples located at 565, 605 and 650 nm are intensified significantly. The present results demonstrate that theSm^（3＋）-doped SAS glassceramics are promising luminescence materials for white LED devices by fine controlling and combining of these three green, orange and red lights in appropriate proportion.
基金Project (2009AA035002) supported by the High-tech Research and Development Program of China
文摘Erbium-doped BaTiO3 films on LaNiO3/Si substrates were fabricated by sol-gel method. The crystalline structure, morphologies and upconversion （UC） luminescence properties of films were respectively investigated by X-ray diffraction （XRD）, atomic force microcopy （AFM） and photoluminescence （PL）. The results indicate that both of the microstructure and luminescence are found to be dependent on Er^3＋ substituting sites. The samples with A-site substitution have smaller lattice constants, larger grains and smoother surface than those with B-site substitution. The photoluminescence spectra show that both of the samples have two stronger green emission bands centered at 528 and 548 nm and a weak red emission band centered at 673 nm, which correspond to the relaxation of Er^3＋ from ^2H11/2, ^4S3/2, and ^4F9/2 levels to the ground level ^4I15/2, respectively. Compared with B-site doped films, A-site doped films have a stronger integrated intensity of green emissions and a weaker relative intensity of red emissions. The differences could be explained by the crystalline quality and cross relaxation （CR） process.
基金Projects(5070202051402100+5 种基金81171461)supported by the National Natural Science Foundation of ChinaProject(11JJ4013)supported by the Natural Science Foundation of Hunan Province,ChinaProject(2013GK3155)supported by Science&Technology Project of Hunan Province,ChinaProject supported by the Youth 1000 Talent Program of ChinaProject supported by the Interdisciplinary Research Program of Hunan University,ChinaProject supported by the Young Teacher Promotion Fund by Hunan University,China
文摘A series of Zr-doped CaTiO3 powders were prepared with the mild co-precipitation method and calcined at 850℃ for 3 h. The as-prepared Zr-doped CaTiO3 samples were characterized by scanning electron microscopy （SEM）, X-ray diffraction （XRD）, UV-Vis diffuse reflectance spectra （DRS） and X-ray photoelectron spectra （XPS）. XRD result revealed the presence of single perovskite phase of CaTiO3. UV-Vis diffusive reflection spectra of Zr-doped CaTiO3 indicated that the absorbance obviously increased in the visible light irradiation. XPS analysis showed that two types of oxygen existed on the photocatalyst surface, including lattice oxygen and absorbed oxygen. Their photocatalytic activity in the case of the degradation of methyl orange in water and photoelectrochemical activity were also tested. The 5%Zr-doped （mole fraction） CaTiO3 sample showed the highest photocatalytic activity. The enhanced photocatalytic activity was ascribed to the change of the lattice structure, existence of oxygen vacancies and increase of the photogenerated charge separation efficiency.
基金Founded by the Science and Technology Foundation of AnhuiProvince (No.010301E2)
文摘Fe^3＋ -doped nanometer TiO2 photocatalysts were prepared by sol-gel technique. TiO2 powders with different Fe^3＋ / Ti^4 ＋ molar ratios ranging from 0. 05% to 25% were synthesized by calcinating the gels in the temperature range of 200-600 ℃ . The effects of the content of iron ions and calcination temperature on the physical properties of the powders and their photocatalytic activities were examined by the photodecorapositon of methyl orange in sunlight. The results show that Fe dopant can decrease the temperature of nanatase-ratile transformation. The ideal photocatalytic property was achieved when the sample with an Fe^3＋ / Ti^4＋ ratio of 20 at% was calcined at about 300 ℃ for an hour, which is superior to that of commercial Degussa P-25. The optimum microstructure of the Fe-doped TiO2 for a high photocatalytic activity in sunlight is consisted of nanatase and ratile.
