A. N. Baranov

Direct Synthesis of Bi-2212 by Thermal Decomposition of Salt Precursors

Thermal decomposition of freeze-dried nitrate precursors with cation ratio Bi:Pb:Sr:Ca:Cu=1.8:0.4:2:2:3 resulted in formation of the Bi-2212 phase within 10 min of thermal treatment at 860°C. The key features of the process are fast heating rate during decomposition, high chemical homogeneity of precursor, and prevention of melting of the copper nitrate by additional thermal dehydration at 100–120°C. The reactivity of the (Bi,Pb)-2223 precursor obtained this way can be further enhanced by heat treatment at reduced P(O2). Analysis of the processes occurring during this treatment shows that the redistribution of Pb between eutectic mixtures of cuprates and (Bi,Pb)-2212 is a possible reason for reactivity enhancement.

Processes in oxide systems under ultrasonic treatment at high temperatures

Joint action of heating and ultrasonic treatment on the real structure of a-Fe O , and the kinetics of the interaction

Fractal surfaces of ZrO2, WO3, and CeO2 powders

The surface fractal properties of ZrO2u2009, WO3u2009, and CeO2 powders prepared by the thermal decomposition of ZrO(NO3)2u2009, (NH4)4W5O17u2009, and (NH4)2Ce(NO3)6u2009, respectively, were studied by mercury porosimetry. The results demonstrate that these oxides may, in principle, have fractal surfaces owing to topochemical processes of the type A(s) → B(s) + C(g). The surface fractal dimension of individual crystallites and their aggregates are determined.

Behaviour of Y2BaCuO5 particles in YBaCuO peritectic melts obtained from different chemical precursors

Abstract The Y2BaCuO5 (211) phase plays a very important role in the formation of Y-based superconducting materials. In this paper, we present the results of studies of 211 phase growth and morphology in peritectic liquid formed upon melt-processing of Y-superconductors. The influence of both the chemical nature and composition of the starting precursors is analysed. Some different ways of obtaining smaller inclusions of 211 in melt are shown. The influence of ultrasonic treatment of samples upon melting is also discussed.