The internal friction and shear modulus of a series of NdxY1−xBa2Cu3Oy (x = 0.0 to 1.0) superconductors were measured over 300 to 700K at frequencies of 0.032 to 10.0Hz using a forced torsional vibration method. Anelastic relaxation peaks due to O migration were observed at 410 to 520K. The Arrhenius plots of logarithmic relaxation time versus inverse peak temperature for the internal friction peaks showed an unsystematic shift with an increase in the Nd composition, while changes of the average cell structure exhibited a linear relationship when plotted versus the average ionic radius for trivalent rare earth ions with a coordination number of 8.

Internal Friction and Oxygen Migration in NdxY1−xBa2CuOy (x = 0.0–1.0) Superconductors at Low Frequencies. M.Inagaki, M.Ozawa: Journal of Alloys and Compounds, 2006, 408-412, 223-5