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ABSTRACT: Microscopic environments and dynamics in LiCoO2 systems were probed by i nuclear magnetic relaxation measurements with regard to the structural defects as revealed by x-ray diffraction and electron spin resonance measurements. Thus, the structural defects of differing degrees, associated with Li vacancies, were well accounted for in the temperature-dependent spin-lattice relaxation rate analysis, and in the structural and dynamical inhomogeneity as derived from the relaxation patterns.
Applied Physics Letters 02/2010; 96(6):062504-062504-3. · 3.84 Impact Factor
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ABSTRACT: Nonradiative energy transfer from the ZnO nanorods (donor) to fluorescent dye-doped polymer (acceptor) was investigated in heterostructures of ZnO nanorods/dye-doped polymer films, with the fluorescent dye, 4-(dicyanomethylene)-2-methyl-6-(4-dimethylaminostyryl)-4H-pyran, being doped into the host material, poly(9-vinylcarbazole). Introduction of the ZnO nanorods layer to the dye-doped polymer film devices turned out to give much enhanced and blueshifted photoluminescence.
Applied Physics Letters 06/2009; 94(23):233301-233301-3. · 3.84 Impact Factor
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ABSTRACT: The benzene ring vibrational motion in poly(phenylenevinylene) has been studied by <sup>1</sup> H nuclear magnetic resonance (NMR) measurements. By employing a simple model of the out-of-plane phenylene oscillation giving rise to a change in the dipolar splitting of the <sup>1</sup> H NMR line shape, the oscillation angle of the benzene ring was obtained as a function of temperature.
Journal of Applied Physics 01/2008; · 2.17 Impact Factor
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ABSTRACT: The structural and magnetic properties in vanadium dioxide ( V O <sub>2</sub>) nanorods prepared by the hydrothermal treatment are shown to be markedly different from the case of the bulk system. A peculiar mixed phase of an insulating monoclinic structure (M<sub>2</sub>) that is observed in the bulk systems under doping or stress and a rutile (R) structure was revealed and confirmed by transmission electron microscopy, x-ray diffraction, and electron spin resonance measurements. Besides, a broad transition from a high-temperature magnetic phase to a low-temperature one, with quite distinct magnetic correlation strengths, was observed.
Applied Physics Letters 11/2007; · 3.84 Impact Factor
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ABSTRACT: Comprehensive measurements of electron spin resonance were carried out on a La0.7Ca0.3MnO3 single crystal over a wide temperature range covering the ferromagnetic as well as the paramagnetic phases. Our analysis of the asymmetric lineshapes indicates that the phase segregation of good and poor conducting regions persists far above the ferromagnetic–paramagnetic phase transition temperature.
Journal of Physics Condensed Matter 06/2003; 15(24):4161. · 2.55 Impact Factor
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ABSTRACT: A La <sub> 0.7 </sub> Ca <sub> 0.3 </sub> MnO <sub>3-δ</sub> single crystal was oxygen-plasma treated at 200 ° C . Our electrical and magnetic measurements indicate that the oxygen-plasma treatment can be an effective low temperature method of oxygen stoichiometry modification of colossal magnetoresistance manganites. The oxygen plasma is also shown to introduce structural defects, whose effects are prominent near the Curie temperature (T<sub>c</sub>), giving rise to anomalies in the resistivity and magnetic behaviors. © 2001 American Institute of Physics.
Applied Physics Letters 01/2002; · 3.84 Impact Factor
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ABSTRACT: Oxygen and hydrogen plasma effects on the superconductivity in MgB2 were investigated. As a result, the critical current density was found to increase by the plasma treatments by an order of magnitude at zero applied magnetic field. The electrical resistivity showed a decrease in the superconducting transition temperature after the plasma treatments, whereas the magnetic susceptibility did not show a change in the transition temperature, indicating percolation of the supercurrent among the superconducting islands in the plasma-treated samples.
Current Applied Physics 11(3):555-558. · 1.90 Impact Factor
