Double perovskite YBaCuFeO5+δ samples were prepared using two different sintering procedures. The interstitial oxygen contents of two samples were different which were estimated from thermogravimetric analysis. The mechanical spectrum below room temperature was measured using the vibrating reed method at kilohertz frequencies. Two internal friction peaks could be discerned in two samples above 200K whose intensities show a correlation with the interstitial oxygen concentration. The lower temperature peak was attributed to the freezing transition of the interstitial oxygen. Another internal friction peak observed around 150K can be explained by the stress induced hopping of electrons in the Fe ion sites.

Mechanical Spectrum and Interstitial Oxygen in YBaCuFeO5+δ. Y.H.Yuan, X.N.Ying: Solid State Sciences, 2012, 14[1], 84–8