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A heteronuclear metal organic framework containing erbium(III) and cobalt(II) ion based on a rigid ligand of substituted imidazoledicarboxylic acid has been synthesized and characterized by single-crystal X-ray diffraction analysis (CIF file CCDC no. 1019455). It's formula is [ErCo(μ-HMimda)(μ-Mimda) · 4HO] · 2 nHO, (HMimda = 1- H-2-methyl-4,5-imidazole-dicarboxylic acid). The complex crystallizes in the monoclinic system. It possesses an extended grid-like porous structure constructed from corrugated shaped 2D layer. Direct current magnetic susceptibility measurements for indicated the depopulation of the Stark components at low temperature and possible very weak antiferromagnetic interactions within heteronuclear MOF. [ABSTRACT FROM AUTHOR]

A novel binuclear iron(III) Schiff base complex [Fe(NO-Salpn)(μ-OH)] · HO ( I) (NO-Salpn = 5-nitrosalicylaldehyde-1,3-propanediamine) has been obtained through one-pot refluxing and condensation. Complex I was established by single-crystal X-ray diffraction analysis (CIF file CCDC no. 1005239) and further characterized by elemental analysis, IR spectroscopy, electrochemical and magnetochemical measurements. Complex I consists of two pseudooctahedral high-spin iron(III) units doubly bridged by two hydroxyl groups. The inter hydrogen bonding interactions connect the adjacent binuclear units into one dimensional (1D) infinite chain, and these 1D chains are further propagated into the two dimensional (2D) supramolecular network by weak intermolecular interactions. Variable temperature magnetic measurements indicate the presence of strong antiferromagnetic interactions between the two adjacent iron(III) ions. [ABSTRACT FROM AUTHOR]

A new cadmium(II) complex [Cd(NO-Salen)] containing Schiff base ligand (NO-Salen = N-mono-5-nitro-salicylideneamino ethanato) has been prepared through facile condensation reaction of sub-stituted salicylaldehyde with ethylene-diamine and has been structurally characterized by elemental analysis, IR spectra and X-ray diffraction. It is formulated as CHCdNO crystallizes in the orthorhombic system, space group of Pccn. The ligand of 5-nitrosalicylaldehyde-ethylene-diamine exhibits unusual mono asymmetry tridentate mode. The Cd ion has a coordination number of six and assumes a distorted octahedral geometry. It exhibits an offset π-π stacking interaction between the substituted benzene ligands of adjacent mononuclear complexes. The neutral monomeric units of [Cd(NO-Salen)] are linked into a one-dimensional (1D) array via the intermolecular hydrogen bonds and π-π stacking interactions. The complex exhibits strong emission in visible region with the maximum wavelength of 428 nm, which is tentatively assigned to the π → π* intraligand fluorescence. [ABSTRACT FROM AUTHOR]

Abstract: Li-rich layered oxide is prepared and coated with an AlF3 layer by a chemical deposition method. The as-prepared and AlF3-coated Li-rich materials are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The as-prepared Li-rich oxide has a typical layered structure with the chemical formula of Li(Li0.17Ni0.25Mn0.58)O2, and the AlF3 layer with a thickness of about 5–7nm is coated on the surface of the Li(Li0.17Ni0.25Mn0.58)O2 grains. Galvanostatic charge–discharge tests at various rates show that the AlF3-coated Li(Li0.17Ni0.25Mn0.58)O2 has an obviously enhanced electrochemical performance compared with the as-prepared sample. At 0.2C rate, the AlF3-coated sample provides a large capacity of more than 250mAhg−1. The coulombic efficiency in the initial cycle is improved to 89.5% from 76.4%. At 5C rate, the reversible capacity of the AlF3-coated sample is stable at above 104mAhg−1 after 200 cycles, much higher than that of the as-prepared sample. According to the analysis from electrochemical impedance spectra (EIS), the improvements of the electrochemical performance are mainly attributed to the pre-activation of the Li-rich layered oxide induced by the AlF3 coating and the maintenance of more active sites for the lithium ion intercalation/extraction in the AlF3-coated sample. [Copyright &y& Elsevier]

The reaction of 2,6-pyridinedicarboxylic acid (HPydc) and ammonium oxalate with neodymium(III) nitrate affords the one-dimensional (1D) neodymium coordination polymer formulated as {[Nd(Pydc)(μ-CO) · 6HO] · 2HO} ( I), and characterized by elemental analysis, IR spectroscopy, and X-ray single-crystal diffraction. The complex presents 1D stair-like chain array bridged through oxalate, and these 1D chains are further linked into 3D supramolecular architecture by extensive intra- and intermolecular hydrogen-bonding interactions. Preliminary magnetic studies reveal the presence of weak antiferromagnetic couplings with the two adjacent magnetic centers bridged through the pyridine dicarboxylate oxygen atom in the complex. [ABSTRACT FROM AUTHOR]

Abstract: In the current study, in order to elucidate the mechanisms for the favorable effects of lithium nitrate in controlling alkali silica reaction (ASR), vycor glass disk immersion specimens and glass disk–cement paste sandwich specimens were prepared and examined by XRD, SEM and Laser Ablation Induction Coupled Plasma Mass Spectrometry (LA-ICP-MS). Results showed that when glass disk was immersed in only NaOH solution, the glass was attacked by hydroxyl ions but no solid reaction product was found, thus the presence of calcium was essential for the formation of ASR gel. In the presence of lithium, the glass surface was covered by a thick layer of Li–Si crystal. With the addition of Ca(OH)2, the glass surface was completely covered by Li–Si crystal and a lithium-bearing low Ca–Na–(K)–Si gel. These two phases either form a dense matrix with Li–Si crystal serving as the framework, and the gel filling in the void space, or the Li–Si crystal serving as the foundation to completely cover the entire reactive SiO2 surface, and the gel sitting on top of these crystal particles. Hence, the suppressive effects of LiNO3 were attributed to the formation of a layer of Li–Si crystals intimately at the reactive SiO2 particle surface and the formation of Li-bearing low-Ca ASR gel products. The Li-bearing low-Ca ASR gels may have a dense and rigid structure, thus having low capacity to absorb moisture from the surrounding paste, and exhibiting a non-swelling property. [Copyright &y& Elsevier]

A new device that enables the application of controlled mechanical loads to devitalized cortical bone blocks in liquid media mimicking physiological environment is described. In the setup, it is possible to evaluate elimination of calcium from a bone during the exposure to slightly acidic media in the presence or absence of periodic controlled mechanical load. In the test experiments with the fragments of cortical bone, the level of calcium elimination from a bone during the experiment has shown the visible dissimilarity for the loaded bone and the unloaded one. The structural alterations in the apatite of the bone after the experiments in the setup have been studied by X-ray diffraction (XRD), which has shown that the lattice microstrain parameter of the bone mineral noticeably increases in the loaded bone compared with unloaded, while the crystallite size shows only a trend to slight increasing. This simple and easy to reproduce bone-loading setup could be used for in vitro studies of the bone material stability under mechanical loading. [ABSTRACT FROM AUTHOR]

A new 2D Mn(II) complex named as [Mn3(HL)2(H2O)6]n (I) (H4L = 3-(2,4-dicarboxyphenyl)-2,6-dicarboxypyridine) was synthesized and characterized by IR, elemental analysis, and single-crystal X-ray diffraction method (CIF file CCDC no. 1915189). The complex crystallizes in the monoclinic space group C2/c with Z = 4, a = 20.6597(11), b = 9.0949(5), c = 20.6041(12) Å, β = 110.056(6)°. The crystal consists of trinuclear Mn(II) ion clusters {Mn3} which are linked by four independent HL3– ligands and these trimeric units are connected into 2D structure by pentadentate HL3– ligand in alternate bis(bridging) and chelated coordination modes. Thermogravimetry, powder X-ray diffraction, and magnetic measurement experiments are also carried out to determinethe thermal stability, phase purity and magnetism. The results show that weak antiferromagnetic interactions occur between the Mn(II) centers within bridging trinuclear {Mn3} cluster. [ABSTRACT FROM AUTHOR]

The crystal structure and superconducting properties of RuSr[sub 2-x]Ba[sub x]GdCu[sub 2]O[sub 8] (0<=x<=0.1) have been investigated. X-ray powder diffraction (XRD) patterns show that the solid solution range is 0<=x<=0.1. The superconducting transition temperature was raised up to 35 K (zero) and 62 K (onset) for x=0.07, from 16 K (zero) and 45 K (onset) for x=0.0, and then T[sub C] decreases with x when x>0.07. Rietveld refinement for XRD data of RuSr[sub 2-x]Ba[sub x]GdCu[sub 2]O[sub 8] show that the apical Cu–O(1) bond length increases with an increase of x, while the Ru–O(1) bond length decreases, This may account for the enhancement of the superconducting transition temperature. © 2004 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Abstract: We investigate thin blend films of phenyl-substituted hexa-peri-hexabenzocoronenes (HBC) with various alkyl side chain lengths ((CH2)n, n=6, 8, 12 and 16)/perylenediimide (PDI). These blends constitute the active layers in bulk-hetero junction organic solar cells we studied recently [1]. Their structural properties are studied by both scanning electron microscopy and X-ray diffraction measurements. The results support the evidence for the formation of HBC donor–PDI acceptor complexes in all blends regardless of the side chain length of the HBC molecule. These complexes are packed into a layered structure parallel to the substrate for short side chain HBC molecules (n=6 and 8). The layered structure is disrupted by increasing the side chain length of the HBC molecule and eventually a disordered structure is formed for long side chains (n>12). We attribute this behavior to the size difference between the aromatic parts of the HBC and PDI molecules. For short side chains, the size difference results in a room for the side chains of the two molecules to fill in the space around the aromatic cores. For long side chains (n>12), the empty space will not be enough to accommodate this increase, leading to the disruption of the layered structure and a rather disordered structure is formed. Our results highlight the importance of the donor–acceptor interaction in a bulk heterojunction active layer as well as the geometry of the two molecules and their role in determining the structure of the active layer and thus their photovoltaic performance. [Copyright &y& Elsevier]

Abstract: Bi3.25Eu0.75Ti3O12 (BET) thin films were deposited on Pt/Ti/SiO2/Si(111) substrates by a metal-organic decomposition method. The effects of annealing temperatures 600–800°C on microstructure, ferroelectric, dielectric and piezoelectric properties of BET thin films were studied in detail. The spontaneous polarization (87.4×10−6 C/cm2 under 300kV/cm), remnant polarization (65.7×10−6 C/cm2 under 300kV/cm), the dielectric constant (992.9 at 100kHz) and the effective piezoelectric coefficient d 33 (67.3pm/V under 260kV/cm) of BET thin film annealed at 700°C are better than those of the others. The mechanisms concerning the dependence of the enhancement d 33 are discussed according to the phenomenological equation, and the improved piezoelectric performance could make the BET thin film a promising candidate for piezoelectric thin film devices. [Copyright &y& Elsevier]