This study delves into the charge transfer mechanism of boron (B)-doped 3C-SiC through first-principles investigations. We explore the effects of B doping on the electronic properties of 3C-SiC, focusing on a 12.5% im...This study delves into the charge transfer mechanism of boron (B)-doped 3C-SiC through first-principles investigations. We explore the effects of B doping on the electronic properties of 3C-SiC, focusing on a 12.5% impurity concentration. Our comprehensive analysis encompasses structural properties, electronic band structures, and charge density distributions. The optimized lattice constant and band gap energy of 3C-SiC were found to be 4.373 Å and 1.36 eV respectively, which is in agreement with previous research (Bui, 2012;Muchiri et al., 2018). Our results show that B doping narrows the band gap, enhances electrical conductivity, and influences charge transfer interactions. The charge density analysis reveals substantial interactions between B dopants and surrounding carbon atoms. This work not only enhances our understanding of the material’s electronic properties, but also highlights the importance of charge density analysis for characterizing charge transfer mechanisms and their implications in the 3C-SiC semiconductors.展开更多
Physical vapor deposition(PVD)can be used to produce high-quality Gd_(2)O_(3)-doped CeO2(GDC)films.Among various PVD methods,reactive sputtering provides unique benefits,such as high deposition rates and easy upscalin...Physical vapor deposition(PVD)can be used to produce high-quality Gd_(2)O_(3)-doped CeO2(GDC)films.Among various PVD methods,reactive sputtering provides unique benefits,such as high deposition rates and easy upscaling for industrial applications.GDC thin films were successfully fabricated through reactive sputtering using a Gd_(0.2)Ce_(0.8)(at%)metallic target,and their application in solid oxide fuel cells,such as buffer layers between yttria-stabilized zirconia(YSZ)/La0.6Sr0.4Co0.2Fe0.8O_(3−δ)and as sublayers in the steel/coating system,was evaluated.First,the direct current(DC)reactive-sputtering behavior of the GdCe metallic target was determined.Then,the GDC films were deposited on NiO-YSZ/YSZ half-cells to investigate the influence of oxygen flow rate on the quality of annealed GDC films.The results demonstrated that reactive sputtering can be used to prepare thin and dense GDC buffer layers without high-temperature sintering.Furthermore,the cells with a sputtered GDC buffer layer showed better electrochemical performance than those with a screen-printed GDC buffer layer.In addition,the insertion of a GDC sublayer between the SUS441 interconnects and the Mn-Co spinel coatings contributed to the reduction of the oxidation rate for SUS441 at operating temperatures,according to the area-specific resistance tests.展开更多
采用溶胶-凝胶法制备出Y_(2-2 x)MgTiO_(6)∶2 x Eu^(3+)(YMT∶2 x Eu^(3+),0≤x≤0.11)新型红色荧光粉。通过X射线衍射仪(XRD)检测样品的纯度,结果显示YMT∶Eu^(3+)样品属于单斜晶系,空间群为P21/n,无其他杂相。扫描电子显微镜(SEM)照...采用溶胶-凝胶法制备出Y_(2-2 x)MgTiO_(6)∶2 x Eu^(3+)(YMT∶2 x Eu^(3+),0≤x≤0.11)新型红色荧光粉。通过X射线衍射仪(XRD)检测样品的纯度,结果显示YMT∶Eu^(3+)样品属于单斜晶系,空间群为P21/n,无其他杂相。扫描电子显微镜(SEM)照片显示荧光粉为2μm的不规则颗粒。当激发波长为264 nm时,发射光谱出现四个尖锐的发射峰,分别位于591(^(5)D_(0)→^(7)F_(1))、619(^(5)D_(0)→^(7)F_(2))、657(^(5)D_(0)→^(7)F_(3))和693 nm(^(5)D_(0)→^(7)F_(4))。Eu^(3+)离子之间能量传递为电偶极子-电偶极子(d-d)相互作用。YMT∶0.14Eu^(3+)荧光粉的CIE色度坐标为(0.645,0.332),与红光标准色坐标(0.67,0.33)非常接近。变温PL光谱及热激活能计算结果显示荧光粉具有一定的热稳定性,因此YMT∶Eu^(3+)是一种具有潜在应用价值的LED红色荧光粉。展开更多
A Eu^3+-doped CaCO3 phosphor with red emission was prepared by microwave synthesis. The scanning electron microscopy (SEM) image and laser particle size analysis show that the CaCO3:Eu^3+ particles are needle-lik...A Eu^3+-doped CaCO3 phosphor with red emission was prepared by microwave synthesis. The scanning electron microscopy (SEM) image and laser particle size analysis show that the CaCO3:Eu^3+ particles are needle-like in the length range of 5.0-10.0 μm. The results of X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy indicate that pure aragonite CaCO3:Eu^3+ is prepared using microwave irradiation and the Eu^3+ ion as a luminescence center inhabits the site of Ca^2+. The photoluminescence excitation (PLE) spectrum shows that the strong broad band at around 270 nm and weak sharp lines in 300-550 nm are assigned to the charge transfer band of Eu^3+-O^2- and intra-configurational 4f-4f transitions of Eu^3+, respectively. The photoluminescence (PL) spectrum implies that the red luminescence can be attributed to the transitions from the ^5D0 excited level to the ^7FJ (J = 0, 1, 2, 3, 4) levels of Eu^3+ ions with the mainly electric dipole transition ^5D0 → ^7F2 (614 and 620 nm), and the Eu^3+ ions prefer to occupy the low symmetric site in the crystal lattice.展开更多
Nanosized Gd2(1–x)Eu2xTi2O7:yV5+ phosphors were prepared via sol-gel method and characterized with X-ray diffraction,Raman spectroscopy,diffuse reflectance spectra and photoluminescence spectra.Their PL properties we...Nanosized Gd2(1–x)Eu2xTi2O7:yV5+ phosphors were prepared via sol-gel method and characterized with X-ray diffraction,Raman spectroscopy,diffuse reflectance spectra and photoluminescence spectra.Their PL properties were investigated as functions of the Eu3+ doping concentration and annealing temperature.The results indicated that the as-prepared samples showed a strong emission of Eu3+ under the irradiation of 303 nm.For Eu3+-doped Gd2Ti2O7,the orange emission at 586 nm was the strongest,which was correspond...展开更多
Y2O3:Eu3+ phosphors co-doped with different metal cations (Li+, Na+, K+, Mg2+, Ca2+) are prepared by the gel- combustion method with Y2O3:Eu3+, and R(NO3)x (R = Li, Na, K, Mg, Ca) serving as raw materi...Y2O3:Eu3+ phosphors co-doped with different metal cations (Li+, Na+, K+, Mg2+, Ca2+) are prepared by the gel- combustion method with Y2O3:Eu3+, and R(NO3)x (R = Li, Na, K, Mg, Ca) serving as raw materials and glycine as fuel, calcined at 1000 ℃ for 2 h. The synthesized Y203 :Eu3+ phosphors doped with different metal cations and doping ratios are characterized by x-ray diffractometry (XRD), fluorescence and phosphorescent spectrophotometer. The co-doping metal cations are advantageous to the development of Y203:Eu3+ lattice. All the samples can emit red light peaked at 611 nm under 254-nm excited. The luminescence intensities of co-doping samples are increased because the cations increase the electron transition probability of Eu3+ from 5D0 level to 7F level. The fluorescence lifetime of Eu3+ (SD0 --+7F2) is increased by doping metal cations.展开更多
Long lasting phosphorescence (LLP) was observed in Eu2+, Ce3+ co-doped strontium borate glasses prepared under the reducing atmosphere due to the emission of both Eu2 + and Ce3+ . The methods of photoluminescence, the...Long lasting phosphorescence (LLP) was observed in Eu2+, Ce3+ co-doped strontium borate glasses prepared under the reducing atmosphere due to the emission of both Eu2 + and Ce3+ . The methods of photoluminescence, thermolu-minescence and phosphorescence were used to study the samples, and possible mechanism was suggested. The co-doping of Ce3 + ions poisoned the phosphorescence emission of Eu2 + because of the competition to obtain the trapped electron . The phosphorescence of Ce3 + in the sample decays more quickly than that of Eu2 + , which is suggested for the reason that the emission energy of Ce3 + is higher or the distance between Ce3 + and electron traps of the glasses is longer.展开更多
The photoluminescence (PL) characteristics of Eu^3+ and Li^+ co-doped ZnO PL materials against heat-treatment temperature were discussed. The PL xerogel and powder samples were prepared by solgel process. The emis...The photoluminescence (PL) characteristics of Eu^3+ and Li^+ co-doped ZnO PL materials against heat-treatment temperature were discussed. The PL xerogel and powder samples were prepared by solgel process. The emission spectra of all samples showed two broad bands peaking at 590 nm and 620 nm under UV-Vis excitation. But the relative intensity of red PL (620 nm) was much greater than that of green PL (590 nm) of the same sample, that s to say, the red color was the main luminescence. With heat-treatment temperature increase, the two kinds of colors PL intensity decreased, and both the red and green PL intensity of the xerogel samples was much greater than those of powder samples respectively. The XRD patterns revealed that Eu^3+ ions were successfully incorporated in ZnO crystals in xerogel samples. When heat-treatment temperature reached 350 ℃, the Eu^3+ began to separate out of the ZnO crystals and Eu2O3 crystals came into being. When the powder sample was subjected to UV-Vis excitation, the energy transfered from the host ZnO emission to Eu^3+ became weaker than the xerogel sample.展开更多
文摘This study delves into the charge transfer mechanism of boron (B)-doped 3C-SiC through first-principles investigations. We explore the effects of B doping on the electronic properties of 3C-SiC, focusing on a 12.5% impurity concentration. Our comprehensive analysis encompasses structural properties, electronic band structures, and charge density distributions. The optimized lattice constant and band gap energy of 3C-SiC were found to be 4.373 Å and 1.36 eV respectively, which is in agreement with previous research (Bui, 2012;Muchiri et al., 2018). Our results show that B doping narrows the band gap, enhances electrical conductivity, and influences charge transfer interactions. The charge density analysis reveals substantial interactions between B dopants and surrounding carbon atoms. This work not only enhances our understanding of the material’s electronic properties, but also highlights the importance of charge density analysis for characterizing charge transfer mechanisms and their implications in the 3C-SiC semiconductors.
基金financially supported by the National Key R&D Program of China (No. 2018YFB1502203-1)the Guangdong Basic and Applied Basic Research Foundation (No. 2021B1515120087)the Stable Supporting Fund of Shenzhen, China (No. GXWD20201230155427003-202007 28114835006)
文摘Physical vapor deposition(PVD)can be used to produce high-quality Gd_(2)O_(3)-doped CeO2(GDC)films.Among various PVD methods,reactive sputtering provides unique benefits,such as high deposition rates and easy upscaling for industrial applications.GDC thin films were successfully fabricated through reactive sputtering using a Gd_(0.2)Ce_(0.8)(at%)metallic target,and their application in solid oxide fuel cells,such as buffer layers between yttria-stabilized zirconia(YSZ)/La0.6Sr0.4Co0.2Fe0.8O_(3−δ)and as sublayers in the steel/coating system,was evaluated.First,the direct current(DC)reactive-sputtering behavior of the GdCe metallic target was determined.Then,the GDC films were deposited on NiO-YSZ/YSZ half-cells to investigate the influence of oxygen flow rate on the quality of annealed GDC films.The results demonstrated that reactive sputtering can be used to prepare thin and dense GDC buffer layers without high-temperature sintering.Furthermore,the cells with a sputtered GDC buffer layer showed better electrochemical performance than those with a screen-printed GDC buffer layer.In addition,the insertion of a GDC sublayer between the SUS441 interconnects and the Mn-Co spinel coatings contributed to the reduction of the oxidation rate for SUS441 at operating temperatures,according to the area-specific resistance tests.
文摘采用溶胶-凝胶法制备出Y_(2-2 x)MgTiO_(6)∶2 x Eu^(3+)(YMT∶2 x Eu^(3+),0≤x≤0.11)新型红色荧光粉。通过X射线衍射仪(XRD)检测样品的纯度,结果显示YMT∶Eu^(3+)样品属于单斜晶系,空间群为P21/n,无其他杂相。扫描电子显微镜(SEM)照片显示荧光粉为2μm的不规则颗粒。当激发波长为264 nm时,发射光谱出现四个尖锐的发射峰,分别位于591(^(5)D_(0)→^(7)F_(1))、619(^(5)D_(0)→^(7)F_(2))、657(^(5)D_(0)→^(7)F_(3))和693 nm(^(5)D_(0)→^(7)F_(4))。Eu^(3+)离子之间能量传递为电偶极子-电偶极子(d-d)相互作用。YMT∶0.14Eu^(3+)荧光粉的CIE色度坐标为(0.645,0.332),与红光标准色坐标(0.67,0.33)非常接近。变温PL光谱及热激活能计算结果显示荧光粉具有一定的热稳定性,因此YMT∶Eu^(3+)是一种具有潜在应用价值的LED红色荧光粉。
基金supported by the National Natural Science Foundation of China (No. 10476024) the Science and Technology Bureau of Sichuan Province, China (No. 2006J13-059)
文摘A Eu^3+-doped CaCO3 phosphor with red emission was prepared by microwave synthesis. The scanning electron microscopy (SEM) image and laser particle size analysis show that the CaCO3:Eu^3+ particles are needle-like in the length range of 5.0-10.0 μm. The results of X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FT-IR), and Raman spectroscopy indicate that pure aragonite CaCO3:Eu^3+ is prepared using microwave irradiation and the Eu^3+ ion as a luminescence center inhabits the site of Ca^2+. The photoluminescence excitation (PLE) spectrum shows that the strong broad band at around 270 nm and weak sharp lines in 300-550 nm are assigned to the charge transfer band of Eu^3+-O^2- and intra-configurational 4f-4f transitions of Eu^3+, respectively. The photoluminescence (PL) spectrum implies that the red luminescence can be attributed to the transitions from the ^5D0 excited level to the ^7FJ (J = 0, 1, 2, 3, 4) levels of Eu^3+ ions with the mainly electric dipole transition ^5D0 → ^7F2 (614 and 620 nm), and the Eu^3+ ions prefer to occupy the low symmetric site in the crystal lattice.
基金supported by Cultivating Innovative Talents for Colleges & Universities of Henan Province (2002006)Open Research Foundation of Henan University
文摘Nanosized Gd2(1–x)Eu2xTi2O7:yV5+ phosphors were prepared via sol-gel method and characterized with X-ray diffraction,Raman spectroscopy,diffuse reflectance spectra and photoluminescence spectra.Their PL properties were investigated as functions of the Eu3+ doping concentration and annealing temperature.The results indicated that the as-prepared samples showed a strong emission of Eu3+ under the irradiation of 303 nm.For Eu3+-doped Gd2Ti2O7,the orange emission at 586 nm was the strongest,which was correspond...
文摘Y2O3:Eu3+ phosphors co-doped with different metal cations (Li+, Na+, K+, Mg2+, Ca2+) are prepared by the gel- combustion method with Y2O3:Eu3+, and R(NO3)x (R = Li, Na, K, Mg, Ca) serving as raw materials and glycine as fuel, calcined at 1000 ℃ for 2 h. The synthesized Y203 :Eu3+ phosphors doped with different metal cations and doping ratios are characterized by x-ray diffractometry (XRD), fluorescence and phosphorescent spectrophotometer. The co-doping metal cations are advantageous to the development of Y203:Eu3+ lattice. All the samples can emit red light peaked at 611 nm under 254-nm excited. The luminescence intensities of co-doping samples are increased because the cations increase the electron transition probability of Eu3+ from 5D0 level to 7F level. The fluorescence lifetime of Eu3+ (SD0 --+7F2) is increased by doping metal cations.
基金Project supported by Technological Key Project of Basic Research of Jilin Province (20020601)
文摘Long lasting phosphorescence (LLP) was observed in Eu2+, Ce3+ co-doped strontium borate glasses prepared under the reducing atmosphere due to the emission of both Eu2 + and Ce3+ . The methods of photoluminescence, thermolu-minescence and phosphorescence were used to study the samples, and possible mechanism was suggested. The co-doping of Ce3 + ions poisoned the phosphorescence emission of Eu2 + because of the competition to obtain the trapped electron . The phosphorescence of Ce3 + in the sample decays more quickly than that of Eu2 + , which is suggested for the reason that the emission energy of Ce3 + is higher or the distance between Ce3 + and electron traps of the glasses is longer.
基金the National Defense Foundation Research Item of China(No.K 1203061109)
文摘The photoluminescence (PL) characteristics of Eu^3+ and Li^+ co-doped ZnO PL materials against heat-treatment temperature were discussed. The PL xerogel and powder samples were prepared by solgel process. The emission spectra of all samples showed two broad bands peaking at 590 nm and 620 nm under UV-Vis excitation. But the relative intensity of red PL (620 nm) was much greater than that of green PL (590 nm) of the same sample, that s to say, the red color was the main luminescence. With heat-treatment temperature increase, the two kinds of colors PL intensity decreased, and both the red and green PL intensity of the xerogel samples was much greater than those of powder samples respectively. The XRD patterns revealed that Eu^3+ ions were successfully incorporated in ZnO crystals in xerogel samples. When heat-treatment temperature reached 350 ℃, the Eu^3+ began to separate out of the ZnO crystals and Eu2O3 crystals came into being. When the powder sample was subjected to UV-Vis excitation, the energy transfered from the host ZnO emission to Eu^3+ became weaker than the xerogel sample.