The kinetics of the formation process of the superconducting phase YBa,Cu,O,, synthesized by the solid state reaction method with the initial mixture of barium carbonate (BaCO,), yttrium oxide (Y,O,) and copper oxide (CuO) has not been studied in full detail up to now. T o gain an insight into the kinetics of the process one has to know its real reaction mechanism. I n this note we attempt to propose a reaction model which seems to be quite adequate in explaining our own experimental results. For this purpose, X-ray powder diffraction, the differential thermal analysis, and the gravimetric methods have been used. Figure 1 represents the time and temperature dependences of the relative weight changes of the phase being formed. The strong temperature dependences (seen from Fig. 1) predict rather high activation energy. Concerning time dependences, the process occurs rapidly at first, but then it is gradually slowed down. Furthermore, the time dependence always undergoes a maximum, and we might assume that the process of weight changes would consist of two main concurrent processes. In this respect let us conventionally distinguish two different regions, one (I) before the maximum and the other (11) after it. To analyse the mechanism of the process consider the general reaction producing the superconducting phase YBaBCu30, as below:
Thermodynamic Analysis and Technology of Preparation ofHigh-T, Superconducting System YBa,Cu,O, -By modeling the equilibrium state of the phase formation reaction of High-T, superconducting phase 1 : 2 : 3 (YBa2Cu30, -J and using the results of P-T-x correlation investigation of some authors, the variation of Gibbs free energy (dGm) versus temperature has been calculated. On the basis of the variation of AGm, the technology procedure of preparation of phase 1 : 2: 3 with desired x has been established to meet requirement of basic investigation and application of High-T, superconductors YBa2Cu,07-,.
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.