A mechanical spectrum study of double perovskite Y 1−xCaxBaCuFeO5+δ

The mechanical spectrum of double perovskite Y BaCuFeO5+δ was measured using the vibrating reed method from 100 K to room temperature at kilohertz frequency. A sharp internal friction peak around 203 K and a broad one around 260 K were observed in Y BaCuFeO5+δ. A deviation of the temperature dependent reduced modulus from linear behavior above 203 K is observed which is concurrent with the sharp internal friction peak. This suggests a phase transition mechanism of the sharp internal friction peak. The intensities of the two internal friction peaks were both depressed upon partial Ca substitution of Y. By comparison of the mechanical spectrum with the bilayer superconductor Y Ba2Cu3O7+δ, one kind of transition in double perovskite oxide is proposed for the sharp internal friction peak.