Search

We report strongly enhanced thermoelectric characteristics for a misfit-layered oxide, [Bi2Ba2O4±ω]0.5CoO2, in a wide temperature range, as achieved through substituting up to 20% of Bi by Pb. The Pb substitution kept the thermal conductivity (κ) unchanged but decreased the electrical resistivity (ρ) and increased the Seebeck coefficient (S) simultaneously, such that a three-fold enhancement in the thermoelectric figure of merit, Z (≡S2/ρκ), was realized. At the same time x-ray absorption near-edge structure data indicated that the valence and spin states of Co are not affected by the Pb-for-Bi substitution. [ABSTRACT FROM AUTHOR]

We report strongly enhanced thermoelectric characteristics for a misfit-layered oxide, [Bi2Ba2O4±ω]0.5CoO2, in a wide temperature range, as achieved through substituting up to 20% of Bi by Pb. The Pb substitution kept the thermal conductivity (κ) unchanged but decreased the electrical resistivity (ρ) and increased the Seebeck coefficient (S) simultaneously, such that a three-fold enhancement in the thermoelectric figure of merit, Z (≡S2/ρκ), was realized. At the same time x-ray absorption near-edge structure data indicated that the valence and spin states of Co are not affected by the Pb-for-Bi substitution. [ABSTRACT FROM AUTHOR]

Makes observations on the supercurrent distribution in YBa[sub 2]Cu[sub 3]O[sub 7-delta] thin films using terahertz radiation excited with femtosecond laser pulses. Characteristics of the transport current distribution; Comparison of current density calculated and measured values; Transition temperature; Film thickness.

Reproducible memory switching has been observed in metal/ Langmuir–Blodgett (LB) film/metal sandwich structures: LB films consist of organic molecules such as dyes having a number of conjugated bonds. The device switches from a nonconducting off state to a conducting on state via an intermediate state, and it switches directly from the on to the off state within less than 10 ns upon the application of a voltage. Both off-state and on-state resistances of the device depend linearly on the number of monolayers, the conduction being predominantly through the LB films. [ABSTRACT FROM AUTHOR]

Ultrashort electromagnetic waves (600 fs width) from superconducting YBCO thin films have been observed by irradiating current-biased samples with femtosecond optical laser pulses (80 fs width). The Fourier component of the pulse extends up to ∼2 THz. The characteristics of the radiation are studied and the radiation mechanism is ascribed to the ultrafast supercurrent modulation by the laser pulses, which induce the nonequilibrium superconductivity. © 1996 American Institute of Physics. [ABSTRACT FROM AUTHOR]