9,418 research outputs found
Method of preventing oxidation of graphite fireproof material
A method of preventing oxidation of graphite fireproof material is given. A blend of 1 to 33 weight parts alumina and 3 to 19 parts of K2O + Na2O in 100 parts of SiO2 is pulverized followed by addition of 5 to 160 parts of silicon carbide powder in 100 parts of the mixture. This is thoroughly blended and coated on the surface of graphite fireproof material
Enhanced thermoelectric properties of NaxCoO2 whisker crystals
Single-crystalline whiskers of thermoelectric cobalt oxide, NaxCoO2, have
been grown by an unconventional method from potassium-containing compositions,
and their transport properties, and chemical compositions were determined. The
growth mechanism was analyzed and interpreted by means of thermogravimetric
analysis. At 300 K, electrical resistivity r and thermoelectric power S of the
whisker are 102 u ohm cm and 83 uV/K, respectively. The power-factor, S2/r,
thus is enhanced up to ~ 68 uW/K2 cm.Comment: 8 pages, 4 figures, to appear in Appl. Phys. Let
Local spin and charge properties of beta-Ag0.33V2O5 studied by 51V NMR
Local spin and charge properties were studied on beta-Ag0.33V2O5, a
pressure-induced superconductor, at ambient pressure using 51V-NMR and
zero-field-resonance (ZFR) techniques. Three inequivalent Vi sites (i=1, 2, and
3) were identified from 51V-NMR spectra and the principal axes of the
electric-field-gradient (EFG) tensor were determined in a metallic phase and
the following charge-ordering phase. We found from the EFG analysis that the V1
sites are in a similar local environment to the V3 sites. This was also
observed in ZFR spectra as pairs of signals closely located with each other.
These results are well explained by a charge-sharing model where a 3d1 electron
is shared within a rung in both V1-V3 and V2-V2 two-leg ladders.Comment: 12pages, 16figure
- …