The studies of the influence of pico-second (4 × 10<sup>-13</sup> sec.) pulse electron irradiation with energy of 3.5 MeV on the electrical-physical properties of silicon crystals (n-Si) are presented...The studies of the influence of pico-second (4 × 10<sup>-13</sup> sec.) pulse electron irradiation with energy of 3.5 MeV on the electrical-physical properties of silicon crystals (n-Si) are presented. It is shown that in spite of relatively low electron irradiation energy, induced radiation defects are of cluster type. The behavior of main carrier mobility depending on temperature and irradiation dose is analyzed and charge carriers’ scattering mechanisms are clarified: on ionized impurities, on point radiation defects with transition into cluster formation. Dose dependencies of electrical conductivity and carrier mobility for samples of various specific resistivities are given.展开更多
The addition of electrons to form gas-phase multiply charged anions(MCAs)normally requires sophisticated experiments or calculations.In this work,the factors stabilizing the MCAs,the maximum electron uptake of gas-pha...The addition of electrons to form gas-phase multiply charged anions(MCAs)normally requires sophisticated experiments or calculations.In this work,the factors stabilizing the MCAs,the maximum electron uptake of gas-phase molecules,X,and the electronic stability of MCAs X^(Q-),are discussed.The drawbacks encountered when applying computational and/or conceptual density functional theory(DFT)to MCAs are highlighted.We develop and test a different model based on the valence-state concept.As in DFT,the electronic energy,E(N,v_(ex)),is a continuous function of the average electron number,N,and the external potential,v_(ex),of the nuclei.The valence-state-parabola is a second-order polynomial that allows extending E(N,v_(ex))to dianions and higher MCAs.The model expresses the maximum electron acceptance,Q_(max),and the higher electron affinities,A_Q,as simple functions of the firstelectron affinity,A_1,and the ionization energy,I,of the"ancestor"system.Thus,the maximum electron acceptance is Q_(max,calc)=1+12A_1/7(I-A_1).The ground-state parabola model of the conceptual DFT yields approximately half of this value,and it is termed Q_(max,GS)=?+A_1/(I-A_1).A large variety of molecules are evaluated including fullerenes,metal clusters,super-pnictogens,super-halogens(OF_3),super-alkali species(OLi_3),and neutral or charged transition-metal complexes,AB_(m )L_n^(0/+/-).The calculated second electron affinity A_(2,calc)=A_1-(7/12)(I-A_1)is linearly correlated to the literature references A_(2,lit) with a correlation coefficient R=0.998.A_2 or A_3 values are predicted for further 24 species.The appearance sizes,n_(ap)^(3-),of triply charged anionic clusters and fullerenes are calculated in agreement with the literature.展开更多
奥氏体不锈钢是不锈钢中产量和用量最大的一种,在石化、核电、食品等众多领域发挥着重要作用,但较低的屈服强度限制了其进一步应用。近年来,高强奥氏体不锈钢的研发已成为不锈钢领域研究热点之一。通过真空冶炼、低温轧制、退火和时效...奥氏体不锈钢是不锈钢中产量和用量最大的一种,在石化、核电、食品等众多领域发挥着重要作用,但较低的屈服强度限制了其进一步应用。近年来,高强奥氏体不锈钢的研发已成为不锈钢领域研究热点之一。通过真空冶炼、低温轧制、退火和时效热处理等工艺制备了屈服强度为676 MPa、抗拉强度为1011 MPa且塑性良好(断后伸长率大于50%)的新型高强高塑性奥氏体不锈钢。时效处理能提高钢的强度,但对耐蚀性的影响及其机理目前尚不明晰。为此,利用SEM(scanning electron microscope)/EBSD(electron back scatter diffraction)、XRD(X-ray diffraction)、XPS(X-ray photoelectron spectroscopy)、TEM(transmission electron microscope)、电化学等方法研究了550℃时效处理对新型奥氏体不锈钢点蚀性能的影响,并探讨了影响机理。结果表明,时效试样的点蚀电位(E_(p))低于未时效试样的,并且随着时效时间的延长,E_(p)逐渐降低,极化电阻(R_(p))逐渐减小,耐点蚀性能缓慢下降;但E_(p)最小也在0.15 V以上,且时效处理对自腐蚀电位和自腐蚀电流密度的影响不明显。此外,时效处理使试样钝化膜中的Cr_(2)O_(3)相对含量低,而NiO、MoO_(3)的相对含量变化不大。这主要是因为,时效处理过程中试样中Cr_(23)C_(6)和NbN等析出相的析出和长大造成了样品中Cr、N元素分布的局部不均匀而导致微区电化学的不均匀,从而使试样的点蚀电位降低以及再钝化能力减弱,而时效处理对影响试样点蚀性能的平均晶粒尺寸、基体相组成等因素无影响。这为开发综合性能更加优异的先进奥氏体不锈钢提供了可能的途径。展开更多
文摘The studies of the influence of pico-second (4 × 10<sup>-13</sup> sec.) pulse electron irradiation with energy of 3.5 MeV on the electrical-physical properties of silicon crystals (n-Si) are presented. It is shown that in spite of relatively low electron irradiation energy, induced radiation defects are of cluster type. The behavior of main carrier mobility depending on temperature and irradiation dose is analyzed and charge carriers’ scattering mechanisms are clarified: on ionized impurities, on point radiation defects with transition into cluster formation. Dose dependencies of electrical conductivity and carrier mobility for samples of various specific resistivities are given.
文摘The addition of electrons to form gas-phase multiply charged anions(MCAs)normally requires sophisticated experiments or calculations.In this work,the factors stabilizing the MCAs,the maximum electron uptake of gas-phase molecules,X,and the electronic stability of MCAs X^(Q-),are discussed.The drawbacks encountered when applying computational and/or conceptual density functional theory(DFT)to MCAs are highlighted.We develop and test a different model based on the valence-state concept.As in DFT,the electronic energy,E(N,v_(ex)),is a continuous function of the average electron number,N,and the external potential,v_(ex),of the nuclei.The valence-state-parabola is a second-order polynomial that allows extending E(N,v_(ex))to dianions and higher MCAs.The model expresses the maximum electron acceptance,Q_(max),and the higher electron affinities,A_Q,as simple functions of the firstelectron affinity,A_1,and the ionization energy,I,of the"ancestor"system.Thus,the maximum electron acceptance is Q_(max,calc)=1+12A_1/7(I-A_1).The ground-state parabola model of the conceptual DFT yields approximately half of this value,and it is termed Q_(max,GS)=?+A_1/(I-A_1).A large variety of molecules are evaluated including fullerenes,metal clusters,super-pnictogens,super-halogens(OF_3),super-alkali species(OLi_3),and neutral or charged transition-metal complexes,AB_(m )L_n^(0/+/-).The calculated second electron affinity A_(2,calc)=A_1-(7/12)(I-A_1)is linearly correlated to the literature references A_(2,lit) with a correlation coefficient R=0.998.A_2 or A_3 values are predicted for further 24 species.The appearance sizes,n_(ap)^(3-),of triply charged anionic clusters and fullerenes are calculated in agreement with the literature.
文摘奥氏体不锈钢是不锈钢中产量和用量最大的一种,在石化、核电、食品等众多领域发挥着重要作用,但较低的屈服强度限制了其进一步应用。近年来,高强奥氏体不锈钢的研发已成为不锈钢领域研究热点之一。通过真空冶炼、低温轧制、退火和时效热处理等工艺制备了屈服强度为676 MPa、抗拉强度为1011 MPa且塑性良好(断后伸长率大于50%)的新型高强高塑性奥氏体不锈钢。时效处理能提高钢的强度,但对耐蚀性的影响及其机理目前尚不明晰。为此,利用SEM(scanning electron microscope)/EBSD(electron back scatter diffraction)、XRD(X-ray diffraction)、XPS(X-ray photoelectron spectroscopy)、TEM(transmission electron microscope)、电化学等方法研究了550℃时效处理对新型奥氏体不锈钢点蚀性能的影响,并探讨了影响机理。结果表明,时效试样的点蚀电位(E_(p))低于未时效试样的,并且随着时效时间的延长,E_(p)逐渐降低,极化电阻(R_(p))逐渐减小,耐点蚀性能缓慢下降;但E_(p)最小也在0.15 V以上,且时效处理对自腐蚀电位和自腐蚀电流密度的影响不明显。此外,时效处理使试样钝化膜中的Cr_(2)O_(3)相对含量低,而NiO、MoO_(3)的相对含量变化不大。这主要是因为,时效处理过程中试样中Cr_(23)C_(6)和NbN等析出相的析出和长大造成了样品中Cr、N元素分布的局部不均匀而导致微区电化学的不均匀,从而使试样的点蚀电位降低以及再钝化能力减弱,而时效处理对影响试样点蚀性能的平均晶粒尺寸、基体相组成等因素无影响。这为开发综合性能更加优异的先进奥氏体不锈钢提供了可能的途径。
基金Exploration Project of Knowledge Innovation Programof Chinese Academy of SciencesShanghai Science and Technology Commission under Grant No.02QF14059.
