共查询到20条相似文献,搜索用时 15 毫秒
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通过Al取代B在B12N12中掺杂,基于密度泛函理论对B6Al6N12的稳定性进行了系统研究.表明在B6Al6N12中,Al和B倾向于相对分开.在最稳定结构中,B原子和Al原子分别处在笼的两半.我们还分析了B12-nAlnN12 (n=0, 6, 12)的电子结构,B12N12的能隙为6.84eV,掺Al后其能隙明显变窄,Al12N12和B6Al6N12的能隙分别为3.91eV和4.08eV.NBO分析表明,B12N12中B/N原子的电荷分别为±1.17,Al12N12中Al/N 原子的电荷分别为±1.85.在B6Al6N12中,B/Al原子上的电荷分别为1.06~1.12和1.86~1.91,N原子上的电荷为-1.18~-1.83. 相似文献
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通过Al取代B在B12N12中掺杂,基于密度泛函理论对B6Al6N12的稳定性进行了系统研究.表明在B6Al6N12中,Al和B倾向于相对分开.在最稳定结构中,B原子和Al原子分别处在笼的两半.我们还分析了B12-nAlnN12 (n=0, 6, 12)的电子结构,B12N12的能隙为6.84eV,掺Al后其能隙明显变窄,Al12N12和B6Al6N12的能隙分别为3.91eV和4.08eV.NBO分析表明,B12N12中B/N原子的电荷分别为±1.17,Al12N12中Al/N 原子的电荷分别为±1.85.在B6Al6N12中,B/Al原子上的电荷分别为1.06~1.12和1.86~1.91,N原子上的电荷为-1.18~-1.83. 相似文献
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Olgierd Dumbrajs 《Zeitschrift für Physik A Hadrons and Nuclei》1980,298(1):61-63
Theπ 12B12C coupling constant is extracted from the data on theM1 form factor of12C using the PCAC and CVC hypotheses. The extrapolation of the form factor to the pion pole using analyticity arguments leads to the value \(f_{\pi ^{12} B^{12} C}^2 = 0.052\) . Our present knowledge of this coupling constant is discussed. 相似文献
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基于对能区70—160MeV 12C+12C散射角分布的分析,建立起一个能量相关的光学势.这个势能很好地再现同一能量区域内的激发函数. 相似文献
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基于密度泛函第一性原理计算,系统研究了Mg12O12笼状团簇组装一维纳米线及其掺杂3d族元素体系的几何结构与电子结构。结果表明:Mg12O12团簇组装一维纳米线为非磁性半导体,带隙值为3.16 eV;掺杂Sc和V后,体系由半导体转变为金属;掺杂Ti、Cr、Mn、Fe、Co、Ni、Cu后体系仍然保持半导体特性、但带隙值明显减小,而掺杂Zn时带隙值变化不大;掺杂V、Cr、Mn、Fe、Co、Ni、Cu后纳米线具有磁性。 相似文献
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12C离子束的剂量学研究 总被引:1,自引:0,他引:1
研究了L-α-丙氨酸剂量计测量^12C离子辐射的剂量学特性,实验证明丙氨酸剂量计适用于^12C离子辐射的剂量学测量。另外,还研究了^12C离子照射人外周血诱发的染色体畸变(双着丝粒+着丝粒环)的剂量效应,在0-8.0Gy范围内拟合的最佳回归方程为Y=0.858503D+0.3615×10^-2D^2。Dosimetric characteristics of L-α-alanine dosemeter used for dosimetry of ^12C ion radiation have been studied. The experimental results indicate that the alanine dosemeter can be used to measure the ^12C ion radiation. In addition, dose effects of chromosome aberration dicentrics and cenric rings were studied after human peripheral blood being irradiated by ^12C ions; the best regression equation, Y = 0. 858 503D + 0. 361 5 ×10^-2D^2, was obtained within 8.0 Gy. 相似文献
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本文主要介绍碳-12为原子量的标准及碳-12标准的国际原子量较之原来的国际原子量的变动情况如何。为了说明这些问题,本文拟就下列几点作简要讨论和介绍:(1)两种原子量标准的共存;(2)统一两种原子量标准的必要性;(3)在什么基础上将两种原子量标准统一起来;(4)采用碳-12=12为统一的原子量标准。 相似文献
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《Journal of Physics and Chemistry of Solids》2002,63(6-8):1207-1210
We derive all symmetry allowed couplings between Fe/Ru or P ion displacements and the Pr ion 4f2 ground state doublet in PrFe4P12 and PrRu4P12. A (1,1,−2)-type distortion of the Fe/Ru positions splits the 4f2 doublet into non-magnetic eigenstates with opposite quadrupole moments. The sign of both the distortion and the quadrupole moment alternate from site to site, resulting in anti-quadrupolar ordering. A (1,1,1)-type distortion does not lift the degeneracy of the 4f2 doublet. Either distortion may also open a gap at the Fermi surface, causing a metal–insulator transition in PrRu4P12 and a partial metal–insulator transition in PrFe4P12. 相似文献
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Astrid Döppenschmidt 《Czechoslovak Journal of Physics》1995,45(7-8):657-661
0-production in the system12C+12C was studied with the two-arm photon spectrometer TAPS at projectile energies of 800 and 1000 MeV/u. The experiments focus on the determination of the cross sections and the correspondingp
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-distributions. The results will extend the existing systematics of
0-production in heavy-ion collisions to a system with small mass.Presented at the International School-Workshop Relativistic Heavy-Ion Physics, Prague (Czech Republic), 19–23 September 1994. 相似文献