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521.
Using first-principles density functional theory calculations within the generalised gradient approximation (GGA) as well as GGA+U method we study Ca-doped α-Cr2O3 crystal. Structural, electronic and magnetic properties due to the singular impurity incorporation have been investigated and discussed in detail. Atomic shifts as well as computed Bader charges on atoms imply the importance of ionic nature in the atomic interactions in chromium oxide. The study improves our knowledge on how the crystalline lattice reacts on the presence of a Ca dopant. According to our research it is found that Ca impurity incorporation produces some local changes upon the electronic band structure of the material without occurrence of local states within the band-gap. It is found that Ca incorporation produces change in magnetic behaviour of the crystal: it becomes ferromagnetic. 相似文献
522.
O8h结构磁空间群C-G系数的计算 总被引:6,自引:0,他引:6
磁空间群相对于以往的空间群,在对物理图像的描述上更准确、更深刻。如它可在考虑晶体对称性的同时,也考虑到自旋磁矩的作用,因而它的C-G系数更加重要。本文利用本征函数法,计算了面心立方结构Oh^8磁空间群的C-G系数,以及波矢选择规则和C-G序列。 相似文献
523.
The hydrothermal reaction of 3,5-pyridinedicarboxylic acid (pydcH2) and Co(NO3)2 or Ni(NO3)2 in the presence of 4,4′-bipyridine results in two novel compounds Co(pydc)(H2O)2 (1) and Ni(pydc)(H2O) (2). Crystal data: 1, monoclinic, C2/c, a=9.900(2), b=11.984(2), c=7.3748(15) Å, β=105.37(3)°, V=843.7(3) Å3, Z=4; 2, monoclinic, P21/c, a=7.7496(6), b=15.0496(11), c=6.4224(5) Å, β=108.437(1)°, V=710.59(9) Å3, Z=4. The structure of 1 is composed of honeycomb layers built up from {CoO4N} trigonal bipyramids and 3,5-pyridinedicarboxylate bridges. The structure of 2 adopts a three-dimensional framework structure in which the Ni atoms are coordinated by the pydc bridges both within the honeycomb layer and between the layers. The magnetic properties of 1 and 2 have been investigated. 相似文献
524.
运用第一性原理计算方法系统研究了二维单层β-GeS中取代掺杂不同3d过渡金属原子时体系磁性、能带结构和光学性质的变化.结果表明:相比于本征非磁性β-GeS,取代掺杂Ti~Cu导致β-GeS具有磁性,且磁矩呈现出先增加后减小的变化趋势;掺杂后体系能带结构发生明显变化,分别表现出金属,半金属和半导体性质,而且导带底的位置明显向Fermi能级方向移动.相比于本征体系,非本征体系的光学性质表明:其在一定波段范围内出现蓝移现象以及光响应强度发生变化,且掺杂前后体系均表现出高的各向异性. 相似文献
525.
It is shown that magnetic surface mode frequencies in the amorphous ferromagnet Fe40Ni40B20 measured using Brillouin light scattering depend upon the incident laser light intensity: presumably due to local heating of the specimen due to the concentration of the light flux into a focal spot only a few microns in diameter. Surface mode frequencies extrapolated to zero light intensity are shown to be consistent with magnetic parameters measured using ferromagnetic resonance at 35.731 GHz to within ±0.5 GHz for specimens of amorphous Fe40Ni40B20. 0.5 GHz corresponds to a change of 0.17 kG in the saturation magnetization, 4πMs. 相似文献
526.
En-Qing Gao Guang-Ming Yang Jin-Kui Tang Dai-Zheng Liao Zong-Hui Jiang Shi-Ping Yan 《Polyhedron》1999,18(27):648-3646
Four novel tetranuclear macrocyclic complexes of the formula [(CuLi)3Fe](ClO4)3·3H2O (i=1–4, Li are the dianions of the [14]N4 and [15]N4 macrocyclic oxamides, namely 2,3-dioxo-5,6:13,14-dibenzo-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene, 2,3-dioxo-5,6:13,14-dibenzo-9-methyl-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene and 2,3-dioxo-5,6:14,15-dibenzo-7,13-bis(ethoxycarbonyl)-1,4,8,12-tetraazacyclotetradeca-7,12-diene] have been prepared and characterized. These complexes are the first examples of oxamido-bridged Cu(II)–Fe(III) heterometallic species. Cryomagnetic studies on [(CuL1)3Fe](ClO4)3·3H2O (1) and [(CuL3)3Fe](ClO4)3·3H2O (3) (77–300 K) revealed that the Cu(II) and Fe(III) ions interact antiferromagnetically through the oxamido bridge, with the exchange integral J=−30.8 cm−1 for 1 and J=−28.7 cm−1 for 3 based on
. The interaction parameters have been compared with that of the related [Cu3Mn] compound. 相似文献
527.
Co(C2(COO)2)(H2O)4 · 2 H2O and Co(C2(COO)2)(H2O)2: Two Co‐ordination Polymers of the Acetylenedicarboxylate Dianion By reaction of CoCO3 with an aqueous solution of acetylenedicarboxylic acid and subsequent crystallisation single‐crystals of Co(C2(COO)2)(H2O)4 · 2 H2O were obtained (P21/a, Z = 2). In the solid state structure cobalt is octahedrally surrounded by four water molecules and two oxygen atoms of the carboxylate anions. These octahedra are connected to chains by the dicarboxylates. Already at ambient conditions Co(C2(COO)2)(H2O)4 · 2 H2O looses four water molecules to give Co(C2(COO)2)(H2O)2 (isotypic to Mn[C2(COO)2] · 2 H2O, C2/c, Z = 4). The cobalt cation is now octahedrally co‐ordinated by two water molecules and four oxygen atoms of the dicarboxylate ligands, which connect the Co octahedra to a three dimensional network. Thermoanalytical investigations show another mass loss at about 200 °C, which leads to non‐crystalline products. Measurements of the magnetic susceptibilities result in the expected behaviour for Co2+ in an octahedral co‐ordination (high spin, 4T1 ground state). The effective magnetic moment at room temperature is neff = 5.51 μB. 相似文献
528.
H. G. von Schnering R. Türck W. Hnle K. Peters E.‐M. Peters R. Kremer J.‐H. Chang 《无机化学与普通化学杂志》2002,628(12):2772-2777
CsMn2P2, a Manganese(II, III) Phosphide with BaZn2P2 Structure. With a Contribution to the BaAl4 Structure Type CsMn2P22is formed by the reaction of Cs4P6 with Mn and red phosphorus (Nb ampoule; 1073 K) as black platelets. The compound is paramagnetic following the Curie‐Weiss law above 110 K (μ = 4.81 B.M. / CsMn2P2; θ = —79 K) and orders antiferromagnetically below 110 K. The magnetic moment corresponds with the ratio MnII : MnIII = 1:1. CsMn2P2 is isotypic with BaZn2P2 (tI10; I4/mmm; a = 4.098(1) Å, c = 14.215(4) Å, d(Mn—P) = 2.387(1) Å (4×), d(Cs—P) = 3.718(2) Å (8×)), and shows, therefore, no P—P‐bonds. The different regions of the BaAl4 (ThCr2Si2) structure type are analysed and parameterized once more. 相似文献
529.
530.
Structure and Magnetism of Fluorides Cs2MCu3F10 (M = Mg, Mn, Co, Ni), Variants of the CsCu2F5 Type X‐ray structure determinations of single crystals showed that compounds Cs2MCu3F10 crystallize with Z = 2 in space group P21/n (No.14) (M = Mn) of the CsCu2F5 type resp. in its supergroup I2/m (No.12) (M = Mg, Co, Ni). Cs2MgCu3F10: a = 714.9(1), b = 736.8(1), c = 940.4(1) pm, b = 96.29(1)°, (Mg‐F: 199.2 pm); Cs2MnCu3F10: a = 725.1(1), b = 742.7(1), c = 951.0(2) pm, b = 97.28(3)°, (Mn‐F: 209.1 pm); Cs2CoCu3F10: a = 717.8(3), b = 739.1(2), c = 939.4(4) pm, b = 97.49(2)°, (Co‐F: 203.1 pm); Cs2NiCu3F10: a = 716.3(1), b = 737.7(1), c = 938.2(2) pm, b = 97.09(1)°, (Ni‐F: 201.0 pm). As determined directly for the Mg compound and generally concluded from the average distances M‐F noted, M substitution concerns mainly the octahedrally coordinated position of the CsCu2F5 structure, the distortion of which is very much reduced thereby. Within the remaining [CuF4] and [CuF5] coordinations, in contrast to CsCu2F5, one F ligand is disordered, in case of the Mn compound the pyramidally coordinated Cu atom, too. The magnetic properties are complex and point to frustration and spin glass effects. Only at the diamagnetically substituted variants with M = Mg, Zn no Néel point appears, which is reached at 27, 23, 36 and 55 K for M = Mn, Co, Ni and Cu, resp. At lower temperatures ferri‐ resp. weak ferromagnetism and hysteresis is observed. 相似文献