Teruki Motohashi

Simultaneously enhanced thermoelectric power and reduced resistivity of NaxCo2O4 by controlling Na nonstoichiometry

Electrical resistivity (ρ) and thermoelectric power (S) were measured for NaxCo2O4 samples with various Na contents (x). A highly precise control of Na nonstoichiometry was facilitated by optimizing the synthesis procedure. With increasing x, the absolute value of ρ monotonically decreased, while the value of S increased. For the x=1.5 sample, S reached a value as high as ∼120 μV/K (at 300 K).

Electrochemical synthesis and properties of CoO2, the x=0 phase of the AxCoO2 systems (A=Li,Na)

Single-phase bulk samples of the “exotic” CoO2, the x=0 phase of the AxCoO2 systems (A=Li,Na), were successfully synthesized through electrochemical deintercalation of Li from pristine LiCoO2 samples. The samples of pure CoO2 were found to be essentially oxygen stoichiometric and possess a hexagonal structure consisting of stacked triangular-lattice CoO2 layers only. The magnetism of CoO2 is featured with a temperature-independent susceptibility of the magnitude of 10−3emu∕molOe, being essentially identical to that of a Li-doped phase, Li0.12CoO2. It is most likely that the CoO2 phase is a Pauli-paramagnetic metal with itinerant electrons.

Static magnetic order in Na 0.75 CoO 2 detected by muon spin rotation and relaxation

The nature of the magnetic transition of the Na-rich thermoelectric

Electronic phase diagram of the layered cobalt oxide system LixCoO2(0.0<x<1.0)

{\mathrm{Na}}_{0.75}{\mathrm{CoO}}_{2}

Positive and negative magnetodielectric effects in A-site ordered (BiMn3)Mn4O12 perovskite

at 22 K was studied by positive muon-spin-rotation and relaxation

Enhanced thermoelectric properties of NaxCoO2 whisker crystals

({\ensuremath{\mu}}^{+}\mathrm{SR})

Competition between ferromagnetism and spin glass : The key for large magnetoresistance in oxygen-deficient perovskites SrCo1-xMxO3-δ (M=Nb,Ru)

spectroscopy, using a polycrystalline sample in the temperature range between 300 and 2.5 K. Zero-field

Impact of lithium composition on the thermoelectric properties of the layered cobalt oxide system LixCoO2

\ensuremath{\mu}\mathrm{SR}

Fabrication and thermoelectric characteristics of [(Bi,Pb)2Ba2O4±w]0.5CoO2 bulks with highly aligned grain structure

measurements indicated the existence of a static internal magnetic field at temperatures below 22 K

Measurement of electron correlations in LixCoO2 (x=0.0–0.35) using 59Co nuclear magnetic resonance and nuclear quadrupole resonance techniques

{(=T}_{\mathrm{m}}).