An investigation was made into the effect of doping with the elemental crystal Ge or/and GeO2 on the TiO2-V2O5-Y2O3 varistor ceramics. The result shows that as the doping contents of V2O5 and Y2O3 are 0.5 tool%, respe...An investigation was made into the effect of doping with the elemental crystal Ge or/and GeO2 on the TiO2-V2O5-Y2O3 varistor ceramics. The result shows that as the doping contents of V2O5 and Y2O3 are 0.5 tool%, respectively, co-doping with 0.3 mol% Ge and 0.9 mol% GeO2 makes the highest α value （α = 12.8）, the lowest breakdown voltage Vlmg （VlmA = 15.8 V/ram） and the highest grain boundary barrier ФB （ФB = 1.48 eV）, which is remarkably superior to the TiO2-V2Os-Y203 varistor ceramics undoped with Ge and GeO2 and mono-doped with Ge or GeO2. The TiO2-V2Os-YEO3-Ge-GeO2 ceramic has the prospect of becoming a novel varistor ceramic with excellent electrical properties.展开更多
GeO2–C fibers were successfully synthesized using electrospinning homogeneous sol and subsequent calcination in an inert atmosphere. The spinnable sol was prepared by adding polyacrylonitrile（PAN）and polyvinylpyrro...GeO2–C fibers were successfully synthesized using electrospinning homogeneous sol and subsequent calcination in an inert atmosphere. The spinnable sol was prepared by adding polyacrylonitrile（PAN）and polyvinylpyrrolidone（PVP） in a weight ratio of 1：1 into a mixture with white precipitate produced by dropping GeCl4 into DMF. X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）,thermogravimetric analysis（TGA）, scanning electron microscopy（SEM） and transmission electron microscopy（TEM） were employed to characterize the as-obtained fibers, and electrochemical tests were conducted to measure electrochemical performance of the electrode. The electrospun fibers have uniform diameters of 300 nm. After being calcined at 600 8C for 2 h in Ar, they transform to amorphous GeO2–C fibers with the same morphologies. The Ge O2–C fibers exhibit excellent cycling stability with a high reversible capacity of 838.93 m A h g^-1after 100 cycles at a current density of 50 m A g^-1, indicating the composite fibers could be promising anode candidates for lithium-ion batteries.展开更多
In this paper, oxidation of Ge surface by N2O plasma is presented and experimentally demonstrated. Results show that 1.0-nm GeO2 is achieved after 120-s N20 plasma oxidation at 300 ℃. The GeO2/Ge interface is atomica...In this paper, oxidation of Ge surface by N2O plasma is presented and experimentally demonstrated. Results show that 1.0-nm GeO2 is achieved after 120-s N20 plasma oxidation at 300 ℃. The GeO2/Ge interface is atomically smooth. The interface state density of Ge surface after N20 plasma passivation is about - 3 × 1011 cm-2.eV-1. With GeO2 passivation, the hysteresis of metal-oxide-semiconductor （MOS） capacitor with A1203 serving as gate dielectric is reduced to - 50 mV, compared with - 130 mV of the untreated one. The Fermi-level at GeO2/Ge interface is unpinned, and the surface potential is effectively modulated by the gate voltage.展开更多
The （60 - x）Bi2O3 - xGeO2-30B2O3-10ZnO （x = 5, 10, 20, 30 molar percent） glasses doped with Er^3＋ and Er^3＋/Yb^3＋ were fabricated using the melting method. The thermal stability of the glasses was studied with ...The （60 - x）Bi2O3 - xGeO2-30B2O3-10ZnO （x = 5, 10, 20, 30 molar percent） glasses doped with Er^3＋ and Er^3＋/Yb^3＋ were fabricated using the melting method. The thermal stability of the glasses was studied with their DTA curves. The results show that the difference between the glass transition temperature and the crystallization onset temperature increases with the increase of GeO2 content, indicating that the thermal stability of the glass has become better. The absorption spectra were recorded and the stimulated emission cross sections were calculated using the McCumber theory. The Ω2, O4, and Ω6 parameters,the transition probability, the radiative lifetime, and the fluorescence branch ratio of Er^3＋ for optical transition were calculated from their absorption spectra in terms of reduced matrix U^（t）（λ = 2, 4, 6） character for optical transitions. The infrared emission of Er^3＋ was measured upon excitation with 970 nm light and the full width at half-maximum （FWHM） was estimated from the emission spectra. The pumping efficiency and the intensity of the emission at the 1.54 μm band of Er^3＋ were enhanced considerably by co-doping Yb^3＋ .展开更多
基金Project supported by the National Natural Science Foundation of China(Nos.51262017,51362017)
文摘An investigation was made into the effect of doping with the elemental crystal Ge or/and GeO2 on the TiO2-V2O5-Y2O3 varistor ceramics. The result shows that as the doping contents of V2O5 and Y2O3 are 0.5 tool%, respectively, co-doping with 0.3 mol% Ge and 0.9 mol% GeO2 makes the highest α value （α = 12.8）, the lowest breakdown voltage Vlmg （VlmA = 15.8 V/ram） and the highest grain boundary barrier ФB （ФB = 1.48 eV）, which is remarkably superior to the TiO2-V2Os-Y203 varistor ceramics undoped with Ge and GeO2 and mono-doped with Ge or GeO2. The TiO2-V2Os-YEO3-Ge-GeO2 ceramic has the prospect of becoming a novel varistor ceramic with excellent electrical properties.
基金supported by Shanghai Municipal Education Commission(High-energy Beam Intelligent Processing and Green Manufacturing)and Graduate Students Innovation Program of Shanghai University of Engineering Science(No.E1-0903-15-01040)
文摘GeO2–C fibers were successfully synthesized using electrospinning homogeneous sol and subsequent calcination in an inert atmosphere. The spinnable sol was prepared by adding polyacrylonitrile（PAN）and polyvinylpyrrolidone（PVP） in a weight ratio of 1：1 into a mixture with white precipitate produced by dropping GeCl4 into DMF. X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）,thermogravimetric analysis（TGA）, scanning electron microscopy（SEM） and transmission electron microscopy（TEM） were employed to characterize the as-obtained fibers, and electrochemical tests were conducted to measure electrochemical performance of the electrode. The electrospun fibers have uniform diameters of 300 nm. After being calcined at 600 8C for 2 h in Ar, they transform to amorphous GeO2–C fibers with the same morphologies. The Ge O2–C fibers exhibit excellent cycling stability with a high reversible capacity of 838.93 m A h g^-1after 100 cycles at a current density of 50 m A g^-1, indicating the composite fibers could be promising anode candidates for lithium-ion batteries.
基金supported by the National Basic Research Program of China(Grant No.2011CBA00601)the National Natural Science Foundation of China(Grant Nos.60625403,60806033,and 60925015)
文摘In this paper, oxidation of Ge surface by N2O plasma is presented and experimentally demonstrated. Results show that 1.0-nm GeO2 is achieved after 120-s N20 plasma oxidation at 300 ℃. The GeO2/Ge interface is atomically smooth. The interface state density of Ge surface after N20 plasma passivation is about - 3 × 1011 cm-2.eV-1. With GeO2 passivation, the hysteresis of metal-oxide-semiconductor （MOS） capacitor with A1203 serving as gate dielectric is reduced to - 50 mV, compared with - 130 mV of the untreated one. The Fermi-level at GeO2/Ge interface is unpinned, and the surface potential is effectively modulated by the gate voltage.
文摘The （60 - x）Bi2O3 - xGeO2-30B2O3-10ZnO （x = 5, 10, 20, 30 molar percent） glasses doped with Er^3＋ and Er^3＋/Yb^3＋ were fabricated using the melting method. The thermal stability of the glasses was studied with their DTA curves. The results show that the difference between the glass transition temperature and the crystallization onset temperature increases with the increase of GeO2 content, indicating that the thermal stability of the glass has become better. The absorption spectra were recorded and the stimulated emission cross sections were calculated using the McCumber theory. The Ω2, O4, and Ω6 parameters,the transition probability, the radiative lifetime, and the fluorescence branch ratio of Er^3＋ for optical transition were calculated from their absorption spectra in terms of reduced matrix U^（t）（λ = 2, 4, 6） character for optical transitions. The infrared emission of Er^3＋ was measured upon excitation with 970 nm light and the full width at half-maximum （FWHM） was estimated from the emission spectra. The pumping efficiency and the intensity of the emission at the 1.54 μm band of Er^3＋ were enhanced considerably by co-doping Yb^3＋ .
