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91.
Mitsumoto K Oshiro E Nishikawa H Shiga T Yamamura Y Saito K Oshio H 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(35):9612-9618
Cyanide‐bridged metal complexes of [Fe8M6(μ‐CN)14(CN)10 (tp)8(HL)10(CH3CN)2][PF6]4?n CH3CN?m H2O (HL=3‐(2‐pyridyl)‐5‐[4‐(diphenylamino)phenyl]‐1H‐pyrazole), tp?=hydrotris(pyrazolylborate), 1 : M=Ni with n=11 and m=7, and 2 : M=Co with n=14 and m=5) were prepared. Complexes 1 and 2 are isomorphous, and crystallized in the monoclinic space group P21/n. They have tetradecanuclear cores composed of eight low‐spin (LS) FeIII and six high‐spin (HS) MII ions (M=Ni and Co), all of which are bridged by cyanide ions, to form a crown‐like core structure. Magnetic susceptibility measurements revealed that intramolecular ferro‐ and antiferromagnetic interactions are operative in 1 and in a fresh sample of 2 , respectively. Ac magnetic susceptibility measurements of 1 showed frequency‐dependent in‐ and out‐of‐phase signals, characteristic of single‐molecule magnetism (SMM), while desolvated samples of 2 showed thermal‐ and photoinduced intramolecular electron‐transfer‐coupled spin transition (ETCST) between the [(LS‐FeII)3(LS‐FeIII)5(HS‐CoII)3(LS‐CoIII)3] and the [(LS‐FeIII)8(HS‐CoII)6] states. 相似文献
92.
Bi Y Guo YN Zhao L Guo Y Lin SY Jiang SD Tang J Wang BW Gao S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(44):12476-12481
Single-ion magnets 1 and 2 and their diamagnetic analogues 3 and 4 for magnetic-site dilution were obtained through substitution of the coordinated water molecules of [Ln(TTA)(3)(H(2)O)(2)] (Ln=Dy (1, 2), Y (3, 4); TTA=4,4,4-trifluoro-1-(2-thienyl)-1,3-butanedionate) by 2,2'-bipyridine (1, 3) and 1,10-phenanthroline (2, 4) capping ligands. Their structures and magnetic properties were investigated with the goal of identifying features relevant to modulating relaxation dynamics of single-ion magnets. The metal ions in all complexes adopt an approximately square-antiprismatic (SAP) O(6)N(2) coordination environment. The SAP polyhedrons for both 1 and 2 show slight longitudinal compression, while the coordination sphere of 1 deviates more from an ideal SAP than that of 2, as indicated by the skew angles of the SAP environment. The similar values of U(eff) for the two magnetically diluted samples imply nearly the same distribution of low-lying states for their Dy(III) centers, which is consistent with the slight axial contraction observed for 1 and 2 and further corroborated by ligand-field analysis. The fast quantum tunneling rate τ(QTM) of 1, which is about ten times faster than that of 2, can presumably be associated with the larger rotation of the SAP surroundings. This distortion may result in a significant transverse anisotropy terms, and thus strongly affect the dynamic behavior of the system. 相似文献
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采用制冷机直接冷却的低温超导磁体系统与传统液氮冷却方式相比,具有轻便紧凑、运行简单、维护方便、可长时间连续运行等优点;而脉管制冷由于冷端无运动部件,与传统的G-M制冷机相比,具有结构简单、运行可靠、振动小等优点.本文结合我们在液氮温区脉管制冷方面的技术,从漏热和经济性两方面探讨了将脉管制冷直接用于冷却一个5特斯拉NbTi低温超导磁体的可行性,为后期系统的搭建奠定基础. 相似文献
96.
J.L. Sánchez Ll J.T. Elizalde-GalindoJ.A. Matutes-Aquino 《Solid State Communications》2003,127(7):527-530
High coercivity nanostructured YCo5 powders were successfully prepared by mechanical milling of as-cast alloys and subsequent vacuum annealing. Almost single phase YCo5 alloys, obtained by arc melting, were processed by high energy mechanical milling using a SPEX 8000 mill. After 4 h of milling, powders become nearly amorphous. DSC scans revealed the existence of an irreversible broad exothermic transition with a maximum at 516 °C associated with the crystallization process. Annealing in high vacuum at 800 °C during 2.5 min led to the formation of YCo5 nanoparticles with an average particle size of 12 nm. A high intrinsic coercivity of 7.23 kOe together with a σr/σs ratio of 0.75 were obtained. 相似文献
97.
毕延芳 《核聚变与等离子体物理》1985,(2)
聚变堆的纵场线圈通常采用无弯矩的恒张力线圈,即D形线圈,这是种尺寸巨大且场强高的纵场线圈,其受电磁力的作用机械支撑问題甚突出。 恒张力线圈的概念最初由File等人提出。最初的D形轮廓线(通常称为PrincetonD)是根据纵场场强与半径成反比(即B_θ∝1/R)的简化条件求解的,也就是假定整个环形纵场线圈沿环向连续均匀地分布。但实际上,纵场线圈总是做成分立的。因为诸如各种注入、加热和抽真空等通道需在线圈之间插入,目前的趋势是在满足等离子体外缘磁场纹波要 相似文献
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