130 resultados para Electrical dipoles


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BiSrMn2O6 is prepared by solid state reaction at 850 degrees C. It is tetragonal with a= 0.7821nm c= 0.3790 nm. It is a black n-type semiconductor below 820K. Its resistivity is 3 Omega-CM at room temperature. A semiconductor -metal transition is observed around 820K, Bi1+xSr1-xMn2O6-y is a solid solution for -0.2 less than or equal to x less than or equal to 0.2. Its unit cell dimensions increase but resistivity decreases when the Bi contents increase.

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All the members of the solid solution of YSr2-xCaxV3O9-y have the orthorhombic symmetry. Their electrical and magnetic properties have been studied. The magnetic susceptibility and electrical resistivity increase gradually with x. The system shows paramagnetic behavior both at 300 K and at 77 K. It is shown that a change of valence state of vanadium obviously affects the electrical and magnetic properties of the solid solution.

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Dysprosium and ytterbium monophosphides have been prepared by the solid state reaction. The optical and electrical properties have been studied. Evidence that DyP and YbP are semiconductors has been obtained from the study of the absorption spectrum, the negative temperature coefficient of resistance and the rectifying effect. Their energy gaps are determined as 1.15 eV for DyP and 1.30 eV for YbP, electric conduction type is n-type, resistivities are about 10(-2) ohm cm and Hall mobility is 8.5-80 cm2/Vs. The p-n junction is formed on the LnP/Si.

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The electrical and magnetical properties of LaSr(2-x)Ca(x)V3O9 +/- y have been investigated. The compounds are antiferromagnetic. They show a metallic conduction other than semiconductivity. The trivalent and tetravalent vanadium ions coexist in the system. The magnetic susceptibility increases and the resistivity decreases at room temperature with the increase of x value. It is shown that the change of the valency state of vanadium obviously influences the electrical and magnetical properties of the system.

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The chloride extraction rule of iron artifacts was studied by electrical methods. The effect of the current and potential value on the desalination result of simulated iron artifacts was studied through the galvanostatic and potentiostatic experiments the ingredients of the rust before and after treatments were also analyzed by the X-ray diffraction (XRD). It has been found that the optimal current density was between -0.50 and -0.75 mA/cm(2) and the optimal potential was between -1.175 and -1.200 V. The phase of the samples rusts transformed after treatment, as well as the anti-corrosion performance improved.

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National Science Foundation of China (No. 10032040 and No. 49874013) and Joint Earthquake Science Foundation of China (No. 101119).