Structure and magnetic properties of Ca14MnP11

The compound Ca₁₄MnP₁₁ crystallizes in the Ca₁₄AlSb₁₁ structure type with the tetragonal space group I4₁/acd (Z=8) and lattice parameters of , c=20.7565(9) at 90 K. The structure consists of MnP₄⁹⁻ tetrahedron, P₃⁷⁻ trimer, 4 P³⁻ isolated anions and 14 Ca²⁺ cations. Similar to other compounds of this structure type containing phosphorous, the P₃⁷⁻ trimer has a central P atom that is best modeled in the structure as being equally split between two sites. In addition, there is no additional distortion of the manganese-containing tetrahedron compared with the main group analog, Ca₁₄GaP₁₁, suggesting that the Mn oxidation state is Mn²⁺. Temperature-dependent magnetic susceptibility shows that the compound is paramagnetic over the entire temperature range measured (2-300 K). The data can be fit with a modified Curie-Weiss law and provide an effective magnetic moment of 5.80 (2) B.M. with a Weiss constant of −2.13(2) K and . This moment is significantly higher than those measured for any of the Mn-containing analogs and is consistent with Mn²⁺. This result will be discussed in light of the electron counting scheme for Mn compounds of the Ca₁₄AlSb₁₁ structure-type.     

CAHN－2000磁天平的调试与数据处理系统的研制

叙述了ＣＡＨＮ－２０００磁天平（美国）调试过程中如何解决液氮温区的测试，自制了磁天平与计算机的接口，编写了数据采集、处理和控制等高原 软件，节省了几万美元，部分指标超过原配套水平，三年来仪器在对国同外开放过程中，液氮温区的工作一直正常，实测了上千个样品，提供的数据已撰写数十篇文章在国内外刊物上发表。由此说明，要充分发挥进口仪器的使用效率，必须对仪器的工作原理、结构特点有透乇的了解，同时要有相当的自     

细乳液聚合法制备磁性复合微球及其表征

在制备超细Fe3O4 磁性粒子的基础上 ,以 3种低分子量聚合物Disperbyk 1 0 6、Disperbyk 1 0 8和Disperbyk 1 1 1为Fe3O4 微粒在单体相中的分散稳定剂 ,采用细乳液聚合法制备了平均粒径为 3 40nm的PS Fe3O4 磁性复合微球 .详细研究了分散剂种类对细乳液聚合制备磁性复合微球的影响 ,并采用XRD、TGA和TEM等手段对磁性复合微球的形态、结构及磁响应性等进行了表征 .实验结果证明分散剂的选择对磁性复合微球的成功制备起着至关重要的作用 ,兼具酸性和碱性功能基的分散剂Disperbyk 1 0 6具有更好的分散和稳定效果 .TEM结果表明 ,所制备的复合微球具有一些缺陷 ,而缺陷处往往是Fe3O4 磁性粒子聚集的地方     

[H2en]2{La2M(SO4)6(H2O)2} (M=Co, Ni): First organically templated 3d-4f mixed metal sulfates

The first organically templated 3d-4f mixed metal sulfates, [H₂en]₂{La₂M(SO₄)₆(H₂O)₂} (M=Co 1, Ni 2) have been synthesized and structurally determined from non-merohedrally twinned crystals. The two compounds are isostructural and their structures feature a three-dimensional anionic network formed by the lanthanum(III) and nickel(II) ions bridged by sulfate anions. The La(III) ions in both compounds are 10-coordinated by four sulfate anions in bidentate chelating fashion, and two sulfate anions in a unidentate fashion. The transition metal(II) ion is octahedrally coordinated by six oxygens from four sulfate anions and two aqua ligands. The doubly protonated enthylenediamine cations are located at the tunnels formed by 8-membered rings (four La and four sulfate anions).     

Building three-dimensional metal phosphites from the corner-shared four-membered rings chain

Three new compounds, a one-dimensional (1D) zinc phosphite, (C₄H₈N₂H₄)[Zn(HPO₃)₂] (I), two three-dimensional (3D) metal phosphites (C₄H₈N₂H₄)[Zn₃(HPO₃)₄] (II) and (C₄H₈N₂H₄)[Zn_(3−x)Co_x(HPO₃)₄(H₂O)₂] (x≈0.83) (III) have been synthesized under hydrothermal conditions templated by piperazine and characterized by single-crystal X-ray diffraction, XRD, IR, UV-vis spectra and SQUID magnetometer. Compound I displays 1D chain-like structure, containing corner-shared (cs) four-membered rings. Interestingly, the structures of II and III show 1D chains similar to those observed in I. It is noteworthy that III represents the first cobalt-substituted zinc-phosphite. Crystal data: I, monoclinic, C2/c, a=17.748(2) Å, b=7.428(9) Å, c=8.8071(11) Å, β=105.345(3)°, V=1091.9 Å³, Z=4. II, Monoclinic P2₁/c, a=9.9435(4) Å, b=10.1438(3) Å, c=17.8164(5) Å, β=95.665(2)°, V=1788.27 Å³, Z=4, and III, Monoclinic P2₁/c, a=7.2338(2) Å, b=15.0238(5) Å, c=9.2153(3) Å, β=107.741(2)°, V=953.88(5) Å³, Z=2.     

表面引发原子转移自由基聚合方法合成Fe3O4/PMMA复合纳米微粒

采用表面引发原子转移自由基聚合方法合成了核壳结构的磁性高分子纳米微粒. 作为聚合反应引发剂的3-氯丙酸, 首先与油酸修饰的Fe3O4纳米微粒表面的部分油酸置换, 然后在Fe3O4纳米微粒表面引发甲基丙烯酸甲酯聚合, 合成的纳米复合材料用TEM, FTIR, XRD和DSC表征. 磁性测试结果表明, 所制备的磁性高分子纳米微粒仍具有超顺磁性, 但由于聚合物的存在, 其饱和磁化强度降低.     

Inverse Perovskites (Eu3O)E with E = Sn,In – Preparation,Crystal Structures and Physical Properties

The cubic inverse Perovskites (Eu₃O)In and (Eu₃O)Sn were prepared from the metals and Eu₂O₃ or SnO₂, respectively. For (Eu₃O)In the crystal structure analysis was performed on single crystal X‐ray diffraction data (space group , a = 512.79(3) pm, Z = 1, R_gt(F) = 0.022, wR(F²) = 0.044). The data indicated full occupancy on all sites and a fully ordered structure. According to magnetic susceptibility measurements and X‐ray absorption spectroscopic data at the Eu L_III edge both compounds contain europium in the 4f⁷ (Eu²⁺) electronic state. (Eu₃O)In orders ferromagnetically at 185(5) K, (Eu₃O)Sn shows antiferromagnetic order at 31.4(2) K. Both compounds behave as metallic conductors in electrical resistivity measurements. However, (Eu₃O)In may be classified a metal, while (Eu₃O)Sn is more likely a heavily doped degenerated semiconductor or semimetal according to the absolute values of the resistivity.     

Synthesis, characterization and biological activity of some transition metals with Schiff base derived from 2-thiophene carboxaldehyde and aminobenzoic acid

Metal complexes of Schiff base derived from 2-thiophene carboxaldehyde and 2-aminobenzoic acid (HL) are reported and characterized based on elemental analyses, IR, 1H NMR, solid reflectance, magnetic moment, molar conductance and thermal analysis (TGA). The ligand dissociation as well as the metal-ligand stability constants were calculated pH metrically at 25 degrees C and ionic strength mu=0.1 (1M NaCl). The complexes are found to have the formulae [M(HL)2](X)n.yH2O (where M=Fe(III) (X=Cl, n=3, y=3), Co(II) (X=Cl, n=2, y=1.5), Ni(II) (X=Cl, n=2, y=1) and UO2(II) (X=NO3, n=2, y=0)) and [M(L)2] (where M=Cu(II) (X=Cl) and Zn(II) (X=AcO)). The molar conductance data reveal that Fe(III) and Co(II), Ni(II) and UO2(II) chelates are ionic in nature and are of the type 3:1 and 2:1 electrolytes, respectively, while Cu(II) and Zn(II) complexes are non-electrolytes. IR spectra show that HL is coordinated to the metal ions in a terdentate manner with ONS donor sites of the carboxylate O, azomethine N and thiophene S. From the magnetic and solid reflectance spectra, it is found that the geometrical structure of these complexes are octahedral. The thermal behaviour of these chelates shows that the hydrated complexes losses water molecules of hydration in the first step followed immediately by decomposition of the anions and ligand molecules in the subsequent steps. The activation thermodynamic parameters, such as, E*, DeltaH*, DeltaS* and DeltaG* are calculated from the DrTG curves using Coats-Redfern method. The synthesized ligands, in comparison to their metal complexes also were screened for their antibacterial activity against bacterial species, Escherichia coli, Pseudomonas aeruginosa, Staphylococcus pyogones and Fungi (Candida). The activity data show that the metal complexes to be more potent/antibacterial than the parent Schiff base ligand against one or more bacterial species.     

Cyanidverbrückte Koordinationspolymere aus cis‐ oder trans‐[Ru(tBuNC)4(CN)2] und MnCl2: Zum Einfluß unterschiedlicher Topologien auf die magnetischen Eigenschaften von Materialien

Cyanide Bridged Coordination Polymers from cis‐ or trans‐[Ru(^tBuNC)₄(CN)₂] and MnCl₂: About the Influence of Different Topologies on the Magnetic Properties of Materials The reaction of cis‐ or trans‐[Ru(^tBuNC)₄(CN)₂] with MnCl₂ as an additional transition metal fragment yields the one dimensional coordination polymers {cis‐[Ru(CN)₂(^tBuNC)₄] MnCl₂}_n, ( 1 ), and {trans‐[Ru(CN)₂(^tBuNC)₄]MnCl₂}_n, ( 2 ), with a different arrangement of the metal centers caused by the different stereochemistry of the starting compounds. The variation of the Ru‐C‐N‐Mn geometry nevertheless leads to significant differences in the magnetic properties of 1 and 2 . The coordination polymer derived from trans‐[Ru(^tBuNC)₄(CN)₂] shows a more efficient antiferromagnetic intrachain interaction between the manganese centers compared to the cis‐derivative.     

One-dimensional α-MnO2: Trapping chemistry of tunnel structures, structural stability, and magnetic transitions

Highly crystalline one-dimensional (1D) α-MnO₂ nanostructures were synthesized by a hydrothermal method. All samples were characterized by X-ray diffraction, transmission electron microscope, thermogravimetric and differential scanning calorimeter, and infrared spectroscopy. During the formation reactions, the tunnel structure of 1D α-MnO₂ was simultaneously modified by NH₄⁺ species and water molecules. The amount of NH₄⁺ species that were trapped in the tunnels is almost independent on the reaction temperature, while the total water content increased with the reaction temperature. The average diameter of α-MnO₂ nanorods increased from 9.2 to 16.5 nm when the reaction temperature increased from 140 to 220 °C. 1D α-MnO₂ was destabilized by a subsequent high-temperature treatment in air, which is accompanied by a structural transformation to 1D Mn₂O₃ of a cubic structure. At low temperatures, all 1D α-MnO₂ nanorods showed two magnetic transitions that were characterized by a decreased Néel temperature with rod diameter reduction. According to the effective magnetic moments experimentally measured, Mn ions presented in the nanorods were determined to be in a mixed valency of high spin state Mn⁴⁺/Mn³⁺.