Stability estimation in YBCO by stepwise XRD and kinetic studies through TGA

The stability of the high-temperature superconductor YBa 2 Cu 3 O 7- δ on treatment with water has been examined and quantitatively determined by XRD, AC magnetic susceptibility measurements and TGA, and by calculating the lattice parameters through Cohen's method. The kinetic parameters, viz. activation energy and order of reaction, have been determined from the TGA data. Progressively longer treatment results in the degradation of the material, as evidenced by corresponding changes in the values of lattice parameters, changes in orthorhombicity, and a continuous increase in the value of the activation energy. The reaction leading to the decomposition of the material is found to be of first order.