Electrical properties of inorganic nanowire-polymer composites

Composites of nanowires of ZnO, RuO2 and Ag with polyaniline (PANI) as well as polypyrrole (PPy) have been prepared, for the first time, by an in-situ process, in order to investigate their electrical properties. Characterization by electron microscopy and IR spectroscopy indicates that there is considerable interaction between the oxide nanowires and the polymer. The room-temperature resistivity of the composites prepared in-situ varies in the 0.01-400 Ω cm range depending on the composition. While the resistivities of the PANI-ZnONW and PPy-ZnONW composites prepared by the in-situ process are generally higher than that of PANI/PPy, those of PANI-RuO2NW and PANI-AgNW are lower. Composites of ZnONW with polyaniline prepared by an ex-situ process exhibit a resistivity close to that of polyaniline

Aliovalent titanium substitution in layered mixed Li Ni–Mn–Co oxides for lithium battery applications

Improved electrochemical characteristics are observed for Li[Ni1/3Co1/3-yMyMn1/3]O2 cathode materials when M=Ti and y<0.07, compared to the baseline material, with up to 15percent increased discharge capacity

Inorganic-organic hybrid structures: synthesis, structure and magnetic properties of a new iron oxalatoarsenate,[NH<SUB>3</SUB>(CH<SUB>2</SUB>)CH(NH<SUB>3</SUB>)CH<SUB>3</SUB>]<SUB>3</SUB>[Fe<SUB>6</SUB>(AsO<SUB>4</SUB>)<SUB>2</SUB>(HAsO<SUB>4</SUB>)<SUB>6</SUB>(C<SUB>2</SUB>O<SUB>4</SUB>)<SUB>3</SUB>]

A hydrothermal reaction of a mixture of iron oxalate, arsenic acid, 1,2-diaminopropane and water at 150&#176;C gave rise to a new three-dimensional iron oxalatoarsenate, [NH3(CH2)CH(NH3)CH3]3[Fe6(AsO4)2(HAsO4)6(C2O4)3], I. Crystal data: hexagonal, space group = P-3c1, a=13.9899(12), c=14.936(3) &#197;, V=2531.6(5) &#197;3. The structure consists of layers of vertex-sharing FeO6 octahedral and AsO4 tetrahedral units that form 12-membered apertures. The layers are connected together by the oxalate units, forming a uniform one-dimensional channel that is occupied by protonated amine molecules. Variable temperature powder XRD studies indicates that I loses crystallinity at ~300&#176;C forming an amorphous phase that gives way to crystalline FeAsO4 at ~650&#176;C. Magnetic studies reveal that I is antiferromagnetic with TN=31 K

Inorganic–organic hybrid structures: Synthesis, structure and magnetic properties of a new iron oxalatoarsenate, [NH3(CH2)CH(NH3)CH3]3[Fe6(AsO4)2(HAsO4)6(C2O4)3]

A hydrothermal reaction of a mixture of iron oxalate, arsenic acid, 1,2-diaminopropane and water at 150 degrees C gave rise to a new three-dimensional iron oxalatoarsenate, [NH3(CH2)CH(NH3)CH3](3)[Fe-6(AsO4)(2)(HAsO4)(6)(C2O4)3], I. Crystal data: hexagonal, space group = P-3cl, a = 13.9899(12), c = 14.936(3) angstrom, V,= 2531.6(5) angstrom(3). The structure consists of layers of vertex-sharing FeO6 octahedral and AsO4 tetrahedral units that form 12-membered apertures. The layers are connected together by the oxalate units, forming a uniform one-dimensional channel that is occupied by protonated amine molecules. Variable temperature powder XRD studies indicates that I loses crystallinity at similar to 300 degrees C forming an amorphous phase that gives way to crystalline FeAsO4 at similar to 650 degrees C. Magnetic studies reveal that I is antiferromagnetic with T-N = 31 K

Properties of nanostructured GaN prepared by different methods

Various methods have been employed to prepare nanostructured GaN exhibiting reasonable surface areas. The methods include ammonolysis of &#947;-Ga2O3 or Ga2O3 prepared in the presence of a surfactant, and the reaction of a mixture of Ga2O3 and Ga(acac)3 with NH3. The latter reaction was also carried out in the presence of H3BO3. All the methods yield good GaN samples as characterized by X-ray diffraction, electron microscopy and photoluminescence measurements. Relatively high surface areas were obtained with the GaN samples prepared by the ammonolysis of &#947;-Ga2O3 (53 m2 g&#8722;1), and of Ga2O3 prepared in the presence of a surfactant (66 m2 g&#8722;1). GaN obtained by the reaction of NH3 with a mixture of Ga2O3, Ga(acac)3 and boric acid gave a surface area of 59 m2 g&#8722;1. GaN nanoparticles prepared by the nitridation of mesoporous Ga2O3 samples generally retain some porosity

Computational and Experimental Investigation of Ti Substitution in Li₁(Ni_<i>x</i>Mn_<i>x</i>Co_{1–2<i>x</i>–<i>y</i>}Ti_<i>y</i>)O₂ for Lithium Ion Batteries

Aliovalent substitutions in layered transition-metal cathode materials has been demonstrated to improve the energy densities of lithium ion batteries, with the mechanisms underlying such effects incompletely understood. Performance enhancement associated with Ti substitution of Co in the cathode material Li₁(Ni_<i>x</i>Mn_<i>x</i>Co_{1–2<i>x</i>})­O₂ were investigated using density functional theory calculations, including Hubbard-U corrections. An examination of the structural and electronic modifications revealed that Ti substitution reduces the structural distortions occurring during delithiation due to the larger cation radius of Ti⁴⁺ relative to Co³⁺ and the presence of an electron polaron on Mn cations induced by aliovalent Ti substitution. The structural differences were found to correlate with a decrease in the lithium intercalation voltage at lower lithium concentrations, which is consistent with quasi-equilibrium voltages obtained by integrating data from stepped potential experiments. Further, Ti is found to suppress the formation of a secondary rock salt phase at high voltage. Our results provide insights into how selective substitutions can enhance the performance of cathodes, maximizing the energy density and lifetime of current Li ion batteries