The twin boundary energy of superconducting YBa2Cu3O7-x was measured as a function of oxygenation temperature, from 450 to 680C, using both the twin spacing method and a twin tip method. By comparing the twin energies obtained using the two methods, the geometrical factor used in the twin spacing method was determined. This factor was directly related to the sharpness of the twin tips. From the temperature dependence of the twin boundary energy per unit area, the twin boundary entropy and enthalpy for twin boundaries were deduced to be 0.24mJK/m2 and 246mJ/m2, respectively.

Enthalpy and Entropy of Twin Boundaries in Superconducting YBa2Cu3O7-x. L.Mei, S.W.Chan: Journal of Applied Physics, 2005, 98[3], 033908