Measurement of Complex Electrical Conductivity of Metallic Powders in a Sealed Tube

Abstract

We studied the method of complex-electrical-conductivity measurement for powders placed in a sealed tube at microwave and millimeter-wave frequencies, using a cavity perturbation technique. We applied this technique to a molecular superconductor K3C60, whose electrical conduction is well known in single crystals, and reproduced the metallic conductivity with the magnitude of 0.5–1.2 mΩcm at 20 K which is in good agreement with the data for single crystals. From this result, it was found that the cavity perturbation technique works well for the conductivity measurement of anaerobic powders, with respect to metallic materials.

Evidence for Insulating Behavior in the Electric Conduction of(NH3)K3C60Kitano1, Matsuo2, Miwa3 et al. 2002Phys. Rev. Lett.382331View full textAdd to dashboardCite

“…By comparing these results with our previous results from K 3 C 60 and ͑NH 3 ͒ x NaRb 2 C 60 (x 0.8, 0.9) [15], and also with the results from other reference powders such as Pb, V 2 O 3 , and C 60 , we concluded that the electric conduction of ͑NH 3 ͒K 32x Rb x C 60 is insulating between 4.5 and 250 K, without any MIT below 250 K. These results are in sharp contrast to the metallic nature of superconducting ͑NH 3 ͒ x NaRb 2 C 60 [15]. The striking difference between both materials strongly indicates that the Mott-Hubbard transition (MHT) in the ammoniated alkali fullerides is driven by a reduction of lattice symmetry from fcc to fco, rather than by the magnetic ordering.…”

“…All sample powders were sealed in glass tubes under He. The average diameter of sample powders were estimated as 10 6 7 mm by the observation of the microscope image [15]. To measure the response 096401-1 0031-9007͞02͞ 88(9)͞096401(4)$20.00…”

“…All sample powders were sealed in glass tubes under He. The average diameter of sample powders were estimated as 10 6 7 mm by the observation of the microscope image [15]. To measure the response for microwave magnetic (H v ) and electric (E v ) fields, we prepared a copper cylindrical cavity resonator operating at 10.7 GHz in the TE 011 mode, so one can choose the sample position between the antinode of the H v field and that of the E v field.…”

“…A set of careful measurements confirmed that the contribution of the glass tube to D͑1͞2Q͒ was very small, although the magnitude of Df͞f was difficult to determine precisely. More details were described elsewhere [15].…”

Microwave electrical resistivity of moderately high Tc superconductor, Y2C3

“…The purpose of this paper is to clarify the electrical properties of Y 2 C 3 by using a microwave cavity perturbation technique. This technique was found to be a very powerful probe to investigate the electrical properties for materials for which a conventional dc resistivity measurement is impossible [3][4][5], because this technique is a contactless technique. Polycrystalline sample of Y 2 C 3 was prepared by using a high pressure equipment.…”