We report on the temperature (20-300 K) dependence of the resistivity, thermopower and thermal conductivity measurements of HgBaCaCuO(1223) polycrystalline superconductors with nominal composition . We present some discussion of the precision and the originality of the measurement methods which are especially used to measure the electrical resistivity and simultaneously the thermopower and the thermal conductivity as a function of temperature. The superconductivity fluctuation contributions to the transport properties of the materials are calculated and compared. The results are related to the 2D anisotropy of the crystallographic structure.
Tungsten oxychloride alone and in combination with Ph4Sn were found to induce a polymerization of phenylacetylene (PhA) totrans-rich poly(phenylacetylene) (PPhA). The binary catalyst has a narrow maximum of the activity at the molar ratio [Ph4Sn]o =y = 2, so that two molecules of Ph4Sn are necessary for a conversion of one molecule of WOCl4 to the most active precursor specie. An identical excess of Ph4Sn acts as a noncompetitive inhibitor (retarder) of the overall polymerization. The order of reaction with respect to catalyst (for y = 2) varies with a concentration of the catalyst. It has value 1 for [WOCl4]o from 0.1 to ca 4 mmol.dm-3 and gradually increases over this concentration limit. Mutual interactions of partially associated growing species, eliminating inhibitive effects of monomer and organotin compounds, are supposed as a reason of this uncommon behaviour. The self inhibitive effect of polymerizing PhA was deduced from the dependence of the initial rate of polymerization on the concentration of PhA. This inhibition takes part most probably in both, the initiation and the propagation. The attempts to determine molecular weights of PPhA by VPO method failed because of a rapid degradation of polymer in diluted solution exposed to atmospheric oxygen.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.