2,089 publications from this institution
Hopping conduction in Ln1 – xSrxCoO3 is discussed in terms of localization due to disorder and in the light of Mössbauer measurements. The hopping times deduced from conductivity and Mössbauer effect differ widely, and an explanation is suggested.
In2O3 nanowires have been prepared by carbon-assisted synthesis starting from In2O3 or In metal. The nanowires have been characterized by X-ray diffraction, electron microscopy and photoluminescence spectroscopy. The nanowires are single crystalline growing in the 〈100〉 direction, as established by high resolution electron microscopy. When a mixture of In2O3 and carbon was used as the starting material, nanowires were obtained along with nanotrees and nanobouquets. The observation of these nanostructures indicates that the growth of the nanowires occurs by the vapor–liquid–solid mechanism. Starting with In metal, only the oxide nanowires were obtained.
Graphyne represents a family of layered artificial carbon allotropes wherein both sp and sp2 hybridized carbon atoms coexist in the lattice with γ-graphyne being the most stable member of the group. Theoretical studies predict γ-graphyne has high carrier mobility (104–105 cm2V−1s−1), exceptional flexibility, low thermal conductance, and charge transport comparable to graphene with a monolayer bandgap of ∼2.23eV. At present experimental exploration of γ-graphyne is still impeded due to the lack of suitable synthesis techniques. We report a simple one-pot Sonogashira cross-linking strategy for the synthesis of pristine γ-graphyne under mild conditions with high yields. As synthesized product was of high purity and exhibited a bandgap of 2.3eV. We believe this synthetic strategy will be helpful in designing similar strategies for the experimental realization of other members of this family. Charge transfer is a fundamental process for understanding a material's properties and tailoring them for various electronic and optoelectronic applications. In this work, UV–visible absorption studies were carried out to understand the charge transfer behavior and defect density of γ-graphyne with donor/acceptor molecules wherein few-layered γ-graphyne showed a comparable/better charge transfer behavior with organic acceptor molecules (TCNQ) than few-layered graphene.
La2CoO4+δ (δ ⋍ 0.1) possessing the K2NiF4 structure has been prepared by skull melting as well as the ceramic method. Evidence for antiferromagnetic ordering has been found in these samples. Stoichiometric La2CoO4 prepared by the reduction of the oxygen excess samples was partially characterized.
No abstract is provided for this article.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Electrical conductivity measurements show that Ln 1−x Sr x CoO 3 , (Ln = Pr or Nd) undergoes a non-metal-metal transition when x≈0 3. The d.c. conductivity of compositions with 0<x<0.l obeys the T −1/4 law up to 400 K and the a.c. conductivity data follow the ω δ law with δ in the range 0.6-0.8. Surprisingly, however, δ seems to increase with increasing temperature. Thermopower measurements show clear evidence for a change in the mechanism of conduction (around 350 K) from variable range hopping to transport at E c . All these transport properties suggest that Co 4+ ions in Ln 1-x Sr x CoO 3 (0<x<0.1), considered as moving in a lattice of Co 3+ , form a degenerate gas and that the states at the Fermi energy are Anderson localized.
No abstract is provided for this article.
An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Magnetic susceptibilities of several members of the series of oxides of the general formula LaNi1−x M x O3 (M = Cr, Fe, or Co) are reported. The oxides show evidence for interesting ferrimagnetic (Cr and Co) and antiferromagnetic (Fe) interactions.
Electronic and magnetic properties of Ln 1−x Sr x CoO3 (Ln = Pr, Nd, Sm, Eu, and Gd) systems show that above a critical value of x, the d electrons become itinerant while the materials become ferromagnetic at low temperatures. The ferromagnetic component increases with increase in x and decrease in temperature. The Curie temperature increases with x and decreases with decrease in the size of the rare-earth ion. Incorporation of Ba2+ in LaCoO3 favors itinerant electron ferromagnetism relative to Sr2+ while Ca2+ is less favorable than Sr2+.
BiCoO3 and BiCo1−xFexO3 (x ≤ 0.7) prepared at atmospheric pressure are found to possess a cubic structure probably involving the Bi12O36 network. BiCoO3 is paramagnetic above 100 K, with a negative paramagnetic Curie temperature. BiCo1−xFexO3 (x = 0.5 or 0.7) is ferromagnetic with Tc ≈ 600K.
