Abstract
The YBaCuFeO5 is the superconductor YBaCu5O5 doped with Fe3+,where Fe3+ replaces Cu2+ in an ordered or disordered manner,depending on the crystal structural arrangement. This makes the space group of YBaCuFeO5 is either P4/mmm or P4mm.The work of this thesis is divided into two parts. First,using multi-beam resonant X-ray diffraction analyzes the structure of YBaCuFeO5 at room temperature when the photon energies are on Cu and Fe K-edges.Second,the magnetic phase transition and the electrical polarization of YBaCuFeO5 occur when the temperature is dropped to 175K or less. At we use multi-beam resonant or non-resonant X-ray diffraction to analyze the structure of YBaCuFeO5.The experiments were carried out at 100K and 250K,using beam-line 07A of NSRRC and 12B of spring8 . We have shown that the space group of YBaCuFeO5 is P4/mmm based on the comparison of the experimental results and the calculations with the dynamical diffraction theory. Also it is proved that Cu and Fe do not share the same site positions and the magnetic phase transition cannot influence the structure of YBaCuFeO5.