Materials Literature
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First-principles calculations of the mayenite-based oxide, [Ca12Al14O32]2+(2e−), reveal the mechanism responsible for its high conductivity. A detailed comparison of the electronic and optical properties of this material with those of the recently discovered transparent conducting oxide, H-doped UV-activated Ca12Al14O…
Mechanical and transport properties were assessed on wheat gluten films with a glycerol content of 25-40%, prepared by compression molding for 5-15 min at temperatures between 90 and 130 degrees C. Effects of storing the films up to 24 days, in 0 and 50% relative humidity (RH), were assessed by tensile measurements. T…
Here we report synthesis and characterization of Mg_{1-x}Sc_{x}B_{2} (0.12T_{c}>6 K. We find that the Sc doping moves the chemical potential through the 2D/3D electronic topological transition (ETT) in the sigma band where the ``shape resonance" of interband pairing occurs. In the 3D regime beyond the ETT we observe a…
Array growth of small-diameter (10–15 nm) zinc oxide (ZnO) nanowires by patterning and template-directed growth methods is reported. The ZnO nanowire arrays (see Figure) were patterned over large areas (∼1 cm2), and exhibited photoluminescence—a characteristic of highly crystalline materials.
We report an ab initio study of the electric-field gradient tensor (EFG) at Cd impurities located at both inequivalent cationic sites in the semiconductor In2O3. Calculations were performed with the FLAPW method, that allows us to treat the electronic structure of the doped system and the atomic relaxations introduced…
Room temperature powder x-ray diffraction measurements have been carried out on polycrystalline samples of CuxV2O5 with x = 0.33, 0.40, 0.50, 0.55 and 0.60, prepared by solid state reaction in evacuated quartz tubes. All the samples were found to be in single-phase monoclinic structure. Rietveld full profile refinemen…
The coexistence of two phases within a particle requires an interface with a significant capillary energy. We show that this entails changes in the nature of alloy phase equilibria at small size. Most notably, the eutectic points in alloy phase diagrams degenerate into intervals of composition where the alloy melts di…
Three-terminal nanorelay structures were fabricated with multiwall carbon nanotubes (MWNTs). The nanotube relays were deflected by applying a gate voltage until contact (mechanical and/or electrical) was made with a drain electrode, thus closing the circuit. It was possible to achieve multiple switching cycles, showin…
Abstract Nature produces a wide variety of exquisite, highly functional mineralized tissues using simple inorganic salts. Biomineralization occurs within specific microenvironments, and is finely tuned by cells and specialized biomacromolecules. This article surveys bio‐inspired approaches to artificial crystallizatio…
Epitaxial assembly of block-copolymer films (see Figure) onto chemically nanopatterned substrates results in arrays of nanoscopic domains that are defect-free, oriented, and registered with the underlying substrate. The range of dimensions of features (or periodicity of structures) that can be patterned with perfectio…
We have investigated the dispersion of single-walled carbon nanotubes (SWNTs) in heavy water with the surfactant octyl-phenol-ethoxylate (Triton X-100) using small angle neutron scattering. The results indicate an optimal surfactant concentration for dispersion, which we suggest results from competition between maximi…
Abstract New frontiers in materials and polymer science include the development of assembly processes that are flexible, allow the access and implementation of nanoscale structure and order, can provide access to a broad range of materials systems, and yet can be implemented at relatively low cost. The ability to fine…
Abstract A new crystalline complex zinc nickel sulfate heptahydrate (ZNSH) has been prepared. The crystal structure was investigated by x‐ray single crystal diffraction method and the empirical formula is Zn 0.24 Ni 0.76 (SO 4 )·7H 2 O. The ZNSH crystal belongs to the orthorhombic space group P2 1 2 1 2 1 with cell pa…
Inelastic neutron scattering spectra from polycrystalline NaH, KH, RbH and CsH, measured at low temperature in the energy transfer range 3 meV< E < 500 meV, are reported. From the medium-energy regions, coinciding with the optical phonon bands, accurate hydrogen-projected densities of phonon states are extracted and c…
Abstract d‐ or f‐mononuclear and d,f‐heterodinuclear complexes with the [1+1] asymmetric compartmental macrocycles H 2 L A , H 2 L B , H 2 L C or H 2 L D , derived from the condensation of 1,2‐diaminoethane or 1,3‐diaminopropane with 3,3′‐(3‐oxapentane‐1,5‐diyldioxy)bis(2‐hydroxybenzaldehyde) or 3,3′‐(3,6dioxaoctane‐1…
There are two growth modes, tip- and base-growth modes, in carbon nanotube (CNT) synthesis. We have shown that the determining factor for the growth mode is the adhesion force of the catalytic metal particles to the substrate through a systematic study of the synthesis in the plasma-enhanced chemical vapour deposition…
Abstract The work is devoted to investigation of stable color centers (CC) that are created in Gd 3 Ga 5 O 12 (GGG) crystals under irradiation with γ‐quanta ( E = 1.25 MeV, D = 10 5 Gy ) as well as transient CC created in the crystals under irradiation with pulsed electron beam ( E = 0.25 MeV, pulse duration 10 ns, fl…
The crystal and magnetic structures of the manganite Pr 0.75 Na 0.25 MnO 3 with non-integer mean valence (Mn 3+ /Mn 4+ ) have been studied by means of powder neutron diffraction at high pressures up to 8 GPa in the temperature range 1.5–295 K. At ambient pressure, the system undergoes a charge ordering at T CO = 220 K…
Abstract Summary: The stability of nanoporous materials as a result of surface interaction forces has been considered in this paper. We show that cylindrical pores in linear elastic materials will collapse if α = γ / μ A > 2. As one would expect physically, smaller cavities tend to be more unstable for the same sur…
The structures of orthorhombic GdAlO3 and GdFeO3 perovskites have been refined at room temperature and pressure using single-crystal x-ray diffraction and their equations of state have been measured to pressures of 7.95 and 7.58 GPa, respectively. Both structures are distorted through the tilting and distortion of the…