Enhancement of flux pinning and critical currents in YBa 2 Cu 3 O 7 − δ films by nanoscale iridium pretreatment of substrate surfacesThis paper shows that the combination of self-assembled structures in the form of "whiskers" and nanoparticles, which appear as a result of the joint sintering powders YBa 2 Cu 3 O 7Àx and arc nanopowders CuO, leads to a significant increase in the current density and the appearance of the peak effect in strong magnetic fields range. Very high critical current density appears from a complex vortex pinning, where the defects in the form of "whiskers" provides more energy of pinning, and nanoparticles inhibit the flux creep. Regulation of the morphology of such structures can be achieved by simple change of the concentration of nanodispersed additives. It is shown that the optimal additive is CuO equal to 20 wt. %. V C 2015 AIP Publishing LLC.

Abstract. The influence of a pressure of gas mixture (10 vol% O 2 + 90% N 2 ) on an average size of copper oxide nanoparticles, produced in the plasma of low pressure arc discharge, has been studied as a basic process variable. A correlation between the dependence of average particle size on gas mixture pressure and the dependence of discharge gap voltage on product of interelectrode distance by a gas mixture pressure, has been found. The estimation was carried out by means of X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HRTEM). A mathematical model of the cathode region, which shows the applicability of the similarity theory to the low pressure arc discharge, has been represented.

Al films were grown by chemical vapor deposition at 400, 550, and 700 °C on GaAs(100) substrates using the molecular precursor dimethylethylamine alane. The film morphology and composition were studied in situ by reflection high-energy electron diffraction and Auger electron spectroscopy, and ex situ by atomic force microscopy and scanning electron microscopy. Chlorine (at 400 °C) and C and N (at 550 and 700 °C) at or below the percent level were found to be the major contaminants of the deposited films. Systematic studies for deposition at 400 °C established that the film microstructure evolves via the growth and coalescence of three-dimensional faceted islands with (100)Al∥(100)GaAs or (110)Al∥(100)GaAs preferential orientation. Coalescence of such crystallites was observed only for equivalent coverages of Al above 150 nm. Comparison with the microstructure of Al films obtained by evaporation suggests that in the temperature range examined the evolution of film morphology during chemical vapor deposition from dimethylethylamine alane was mainly determined by surface diffusion of isolated adsorbed Al atoms.