Based on the factorization theorem for lepton induced hard diffractive scattering and color octet heavy quarkonium production mechanism, ηc diffractive production in the direct photon process is studied. The results ...Based on the factorization theorem for lepton induced hard diffractive scattering and color octet heavy quarkonium production mechanism, ηc diffractive production in the direct photon process is studied. The results show that this process can be measured at DESY HERA, and ηc production has different features from J/Ψ production, which is weakly affected by the initial and final state gluon radiation. Therefore, ηc photoproduction can be viewed as reliable estimate. The experimental study of this process can give valuable insight in the co/or octet heavy quarkonium production mechanism.展开更多
D+2 ions of 70 and 90 keV were separately implanted into two thick samples of sintered alumina ceramic and the distribution of deuterium has been measured for three runs at an interval of 5 months using high energy pr...D+2 ions of 70 and 90 keV were separately implanted into two thick samples of sintered alumina ceramic and the distribution of deuterium has been measured for three runs at an interval of 5 months using high energy proton backscattering and elastic recoil detection (ERD). The measured data show that there is little diffusion of deuterium in A12O3 and the diffusion coefficient is deduced to be 1.1 ×10-17 cm2/s. The measured total concentration of implanted deuterium is 4.5×1018 at./cm2. The profile of hydrogen adsorbed on the surface of Al2O3 samples was also observed by ERD and 1H(19F, αγ)16O analysis. The distribution range of 1H in Al2O3 after deuterium implantation is much larger than that before one.展开更多
High-speed steel W18Cr4V is commonly used in industries such as blade and mould manufacturers because of its high level of hardness and toughness, M-hardness and resistance, Ion implantation is an effective method to ...High-speed steel W18Cr4V is commonly used in industries such as blade and mould manufacturers because of its high level of hardness and toughness, M-hardness and resistance, Ion implantation is an effective method to improve the wear resistance of W18Cr4V. In our investigation, Ta and Ta＋N ion implantation was performed on W18Cr4V high-speed steel. The surface properties after implantation were evaluated by measuring friction coefficients while the cabonyl phase of the surface was analyzed by X-ray diffraction analysis. It was found that the friction coefficients of the treated samples were much lower. Samples implanted with Ta＋N had a lower friction coefficients than samples implanted only with Ta. This can be attributed to the formation of a new chemical compound, Fe7Ta3, on both surfaces. An even harder chemical compound, FerN, was formed on both surfaces of Ta＋N implanted samples.展开更多
(K0.47Na0.47Li0.06)NbO3 (KNLN) lead-free ceramics were prepared by molten salt synthesis (MSS) method using k2CO3-Na2CO3 eutectic mixtures as the flux. The microstructure and piezoelectric properties when sintered at ...(K0.47Na0.47Li0.06)NbO3 (KNLN) lead-free ceramics were prepared by molten salt synthesis (MSS) method using k2CO3-Na2CO3 eutectic mixtures as the flux. The microstructure and piezoelectric properties when sintered at 980-1 030 ℃ were investigated. The calcined powders were examined by X-ray diffraction. The microstructure of the calcined powders and sintered bodies was observed using a scanning electron microscope (SEM).The piezoelectric constant d33 was measured using a quasi-static piezoelectric d33 meter. The planar coupling coefficient Kp was calculated by resonance-antiresonance method. The experimental data for each sample's performance indicators were the average values of 8 specimens. The relative densities of sintered specimens are above 97%, and the dielectric loss is below 0.03. It was found that (K0.47Na0.47Li0.06)NbO3 prepared by MSS is compact and lead-free. The piezoelectric constant d33 is 216 pC·N-1 and the planar electromechanical coupling factor Kp is 0.352.展开更多
The scattering theory in periodic structures has many applications in modern microoptics and industry. Periodic structures are often referred to as diffraction gratings. In this paper we consider a planar dielectric-l...The scattering theory in periodic structures has many applications in modern microoptics and industry. Periodic structures are often referred to as diffraction gratings. In this paper we consider a planar dielectric-layer modulated grating problem. The diffraction problem may be modeled by a Helmholtz equation with periodic coefficients. Results on existence and uniqueness of the solution for the diffraction problem are obtained by variational method and integral equation method, respectively. At the end of the paper, we also discuss the Born approximation to the solution of an equivalent integral equation.展开更多
Crystals of CdSxSe1-x alloys have been grown from the vapour phase. Some of the physical properties, such as lattice parameters, crystal structure and x-rays data of CdSxSe1-x alloys were determined using x-ray diffra...Crystals of CdSxSe1-x alloys have been grown from the vapour phase. Some of the physical properties, such as lattice parameters, crystal structure and x-rays data of CdSxSe1-x alloys were determined using x-ray diffractometry. X-ray diffractometry has shown that CdS-CdSe mixed crystals had the wurtzite structure for all compositions between CdS and CdSe. The lattice parameters （both a and c） were found to show a linear dependence with composition. The dependence of the lattice parameters of a and c on composition can be expressed as： a（x） = 4.165 ＋ 0.16x; c（x） = 6.713 ＋ 0.27x. The variation of band gap with composition was determined for these samples from optical absorption measurements, which showed that the band gap varied smoothly and monotonically, but not linearly over the composition range typical results were found between 2.42-1.74 eV at room temperature.展开更多
文摘Based on the factorization theorem for lepton induced hard diffractive scattering and color octet heavy quarkonium production mechanism, ηc diffractive production in the direct photon process is studied. The results show that this process can be measured at DESY HERA, and ηc production has different features from J/Ψ production, which is weakly affected by the initial and final state gluon radiation. Therefore, ηc photoproduction can be viewed as reliable estimate. The experimental study of this process can give valuable insight in the co/or octet heavy quarkonium production mechanism.
文摘D+2 ions of 70 and 90 keV were separately implanted into two thick samples of sintered alumina ceramic and the distribution of deuterium has been measured for three runs at an interval of 5 months using high energy proton backscattering and elastic recoil detection (ERD). The measured data show that there is little diffusion of deuterium in A12O3 and the diffusion coefficient is deduced to be 1.1 ×10-17 cm2/s. The measured total concentration of implanted deuterium is 4.5×1018 at./cm2. The profile of hydrogen adsorbed on the surface of Al2O3 samples was also observed by ERD and 1H(19F, αγ)16O analysis. The distribution range of 1H in Al2O3 after deuterium implantation is much larger than that before one.
文摘High-speed steel W18Cr4V is commonly used in industries such as blade and mould manufacturers because of its high level of hardness and toughness, M-hardness and resistance, Ion implantation is an effective method to improve the wear resistance of W18Cr4V. In our investigation, Ta and Ta＋N ion implantation was performed on W18Cr4V high-speed steel. The surface properties after implantation were evaluated by measuring friction coefficients while the cabonyl phase of the surface was analyzed by X-ray diffraction analysis. It was found that the friction coefficients of the treated samples were much lower. Samples implanted with Ta＋N had a lower friction coefficients than samples implanted only with Ta. This can be attributed to the formation of a new chemical compound, Fe7Ta3, on both surfaces. An even harder chemical compound, FerN, was formed on both surfaces of Ta＋N implanted samples.
基金Supported by National Natural Science Foundation of China (No.10232030)Key Laboratory for Advanced Ceramics and Machining Technology,Ministry of Education,Tianjin University (No. x06050)
文摘(K0.47Na0.47Li0.06)NbO3 (KNLN) lead-free ceramics were prepared by molten salt synthesis (MSS) method using k2CO3-Na2CO3 eutectic mixtures as the flux. The microstructure and piezoelectric properties when sintered at 980-1 030 ℃ were investigated. The calcined powders were examined by X-ray diffraction. The microstructure of the calcined powders and sintered bodies was observed using a scanning electron microscope (SEM).The piezoelectric constant d33 was measured using a quasi-static piezoelectric d33 meter. The planar coupling coefficient Kp was calculated by resonance-antiresonance method. The experimental data for each sample's performance indicators were the average values of 8 specimens. The relative densities of sintered specimens are above 97%, and the dielectric loss is below 0.03. It was found that (K0.47Na0.47Li0.06)NbO3 prepared by MSS is compact and lead-free. The piezoelectric constant d33 is 216 pC·N-1 and the planar electromechanical coupling factor Kp is 0.352.
文摘The scattering theory in periodic structures has many applications in modern microoptics and industry. Periodic structures are often referred to as diffraction gratings. In this paper we consider a planar dielectric-layer modulated grating problem. The diffraction problem may be modeled by a Helmholtz equation with periodic coefficients. Results on existence and uniqueness of the solution for the diffraction problem are obtained by variational method and integral equation method, respectively. At the end of the paper, we also discuss the Born approximation to the solution of an equivalent integral equation.
文摘Crystals of CdSxSe1-x alloys have been grown from the vapour phase. Some of the physical properties, such as lattice parameters, crystal structure and x-rays data of CdSxSe1-x alloys were determined using x-ray diffractometry. X-ray diffractometry has shown that CdS-CdSe mixed crystals had the wurtzite structure for all compositions between CdS and CdSe. The lattice parameters （both a and c） were found to show a linear dependence with composition. The dependence of the lattice parameters of a and c on composition can be expressed as： a（x） = 4.165 ＋ 0.16x; c（x） = 6.713 ＋ 0.27x. The variation of band gap with composition was determined for these samples from optical absorption measurements, which showed that the band gap varied smoothly and monotonically, but not linearly over the composition range typical results were found between 2.42-1.74 eV at room temperature.
