Mechanical spectrum and interstitial oxygen in YBaCuFeO5+δ

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

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