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Author(s): Wenyu Zhao [1]; Zhiyuan Liu [1]; Zhigang Sun [1]; Qingjie Zhang (corresponding author) [1]; Ping Wei [1]; Xin Mu [1]; Hongyu Zhou [1]; Cuncheng Li [1]; Shifang Ma [1]; [...]

The effect of Ni-Nb co-doping on the structural, electromechanical, and dielectric properties of lead titanate (PT) ceramics is examined. The studies have shown that Ni-Nb co-doping has both softening and hardening effects as a function of donor or acceptor behavior of different amounts of Ni-Nb and the segregation of a small amount of a secondary phase has occurred, lattice constants and tetragonality has decreased and the resulting ceramic has become very hard.

Ternary cobalt-nickel silicide/n-Si Schottky diodes are fabricated by sputtering using an equiatomic cobalt-nickel alloy target. The variations found in barrier height are attributed to the inhomogeneity in Schottky junction.

The phase, the microstructure and the temperature dependent thermoelectric properties of the hot-pressed skutterudite Co[Sb.sub.3] are characterized. The results have shown larger electrical conductivity due to existence of metallic Sb and smaller thermal conductivity due to fine-grained structure and a moderate improvement is found on figure of merit (ZT) for pure Co[Sb.sub.3].

The study of the perpendicular transport properties as a function of both dc electric currents and applied magnetic fields is carried out with the help of a nanoscale pillar consisting of a Co/Cu/Co layered structure that was fabricated by means of electron-beam lithography. Details of the nanopillar that exhibits sharp transitions in magnetoresistance are discussed.

The linear increase of the current perpendicular to plane (CPP) resistance with the number of bilayers in both normal and superconducting Nb/Co multilayers is presented. The unit area resistance of one pair of Co/Nb interfaces were found to be 3.5 plusmn 0.7 and 6.3 plusmn 0.9 f omega m(super 2) for normal and superconducting Nb, respectively.

The influence of the granular microstructure in the electrical resistivity of RF-sputtered Ti(sub 100-x)Co(sub x) thin films is investigated. The magnetic Kondo scattering is responsible for the observed minimum in the resistivity of Ti(sub 93)Co(sub 7) samples grown at 30 W.

The measurement of the infrared reflectance of (Co50Fe50)(sub x) - (Al2O3)(sub 1-x) granular films exhibiting tunneling magnetoresistance in the wavelength range of 2 - 25 mu m for compositions above and below the critical percolation volume fraction is discussed. Around 9 mu m distinctive magnetic signatures are observed below and above the percolation threshold at x = 0.17 at the longitudinal optic reflection edge.

The magnetic and electrical properties of amorphous Co-Fe-Zr-B alloy films with Al and O additions are examined. The annealing of alloy films at 200 degree C for 2 h and in an applied field of ~150 Oe results in a strong uniaxial anisotropy in the film plane.

In situ resistance measurements and scanning tunneling microscopy (STM) were used for examining the origin of diffuse electron scattering at Co/Cu interfaces on a model system of epitaxial (111)-oriented Co on Cu and Cu on Co. The resistance for Co on Cu increased initially by 10 percent at submonolayer coverage and declined after 1-1.5 ML coverage.

Magnetic properties of electrodeposited CoNiFeS films were studied to seek their feasibility for applications in microelectromagnetic devices such as high areal density recording heads. From a processing standpoint, it was able to control the film thickness uniformity by adjusting current distributions between the auxiliary electrode and cathode across 100 mm wafers.

The significance of micelles in the enhancement of coercivity of the single domain cobalt-ferrite nanoparticles is analyzed. The coercivity is shown to also increase with an increase in the particle size and annealing temperature of the system.

A new method is described for preparing layered double hydroxides and its ultrathin nanosheets in de-ionized water by pulsed laser ablation. The laser ablation method has played a critical role in the formation of nanosheets, suggesting that the contamination of the as-synthesized layered double hydroxide colloidal solutions by carbonate is insignificant.

The optical and magneto-optical properties of bulk [L2.sub.1] ordered [Co.sub.2]CrGa Heusler alloy (HA) are examined below and above the Curie temperature and are explained in terms of the band structure. The studies have shown that unlike bulk [L2.sub.1]-type ordered [Co.sub.2]CrGa HA sample, B2 structure order of [Co.sub.2]CrGa HA films have displayed negative temperature coefficient of resistivity.

The mechanism of the oxygen evolution reaction (OER) by catalysts prepared by electrodepositions from [Co.sup.2+] solutions in phosphate electrolytes (Co-Pi) is analyzed at neutral pH by using electrokinetic and [super 18]O isotope experiments. The electrokinetic studies have shown a mechanism involving a rapid, one electron, one proton equilibrium between [Co.sup.III]-OH and [Co.sup.IV]-O in which a phosphate species is the proton acceptor, which is followed by a chemical turnover-limiting process involving oxygen-oxygen bond coupling.

In situ fabrication of [Co.sub.3][O.sub.4] or Pt nanocrystals incorporated into one-dimensional (1D) nanoporous carbons (NPCs) by an organometallic precursor-controlled thermolysis approach is described. The unique 1D metal-carbon hybrids have displayed a promising potential in electrochemical energy storage and NPCs/Pt is applied as an electrocatalyst showing catalytic efficiency toward methanol oxidation in comparison to commercial E-TEK (Pt/C) catalyst.

The optical properties of dissociative luminescent sensors based on a complex consisting of highly luminescent hydrophobic core/shell CdSe/ZnS quantum dots (QDs) and 1-(2-pyridilazo)-2-naphtol (PAN) molecules in organic solutions and a polymer film are studied. [Ni.sup.2+] and [Co.sup.2+] ions are used to show that the QD/PAN sensor can be used in the quantitative luminescent sensing of metal ions in aqueous solutions.

The dependence of the interlayer coupling strength on the MgO spacer thickness is fitted by the theory of free-electron model, which has provided an experimental proof for interlayer exchange coupling theory. The thermal behavior of interlayer coupling in [[Pt/Co].sub.4]/MgO/[[Co/Pt].sub.2] perpendicular magnetic tunnel junctions has shown a translation from antiferromagnetic to ferromagnetic coupling at 145 K, which is attributed to the temperature-dependent enhancement of the magnetization of the ferromagnetic layers.

Single crystalline FeMn/Co bilayers are grown epitaxially on Cu(001) and examined by magneto-optic Kerr effect (MOKE). A thickness dependent study of the magnetic anisotropy constant has shown that this induced magnetic anisotropy has originated from the FeMn/Co interfacial spin frustration.

Several studies are conducted for measuring the magnetofluctuation conductivity of the various doped Ba[Fe.sub.1.8][Co.sub.0.2][As.sub.2] single crystals functioning in the critical region. The superconductivity of the material is shown to exhibit a three-dimensional scaling.