Heterogeneous equilibrium between YBa2Cu3O7-δ and oxygen gas studied by a kinetic approach

• Published in: Journal of materials chemistry Vol. 3; no. 4; pp. 421 - 426
• Main Authors: CELLUCCI, F, CIGNINI, P. L, GOZZI, D, TOMELLINI, M
• Format: Journal Article
• Language: English
• Published: Cambridge Royal Society of Chemistry 1993
• Subjects: Chemistry; Exact sciences and technology; Inorganic chemistry and origins of life; Kinetics and mechanism of reactions; Chemical equilibrium; Superconducting materials; Oxygen; Non stoichiometric compound; Transition metal Compounds; Arrhenius equation; Activation parameter; Lanthanide Compounds; Rate constant; Thermodynamic properties; Alkaline earth metal Compounds; Barium Copper Yttrium Oxides Mixed
• ISSN: 0959-9428; 1364-5501
• DOI: 10.1039/JM9930300421

The kinetic behaviour of the YBa2Cu3O7-delta system was investigated using a 'T-jump' experiment, involving a displacement of the thermodynamic system from equilibrium by a temperature jump. The subsequent relaxation process was followed by means of resistivity measurements. Kinetic models were formulated by assuming the formation of singly and doubly charged oxygen vacancies and according to the kinetic law of mass action. Good agreement between the theoretical model and the experimental data was achieved in the case of singly charged oxygen vacancies in the temperature range 400-800 C. At equilibrium the YBa2Cu3O7-delta conductivity was found to be a function of the oxygen partial pressure P, i.e. sigma proportional to P exp(n) with n between 1/4 and 1/2. 21 refs.