Effect of oxygen content and oxygen vacancy ordering on the properties of TbBaCo2O6-delta perovskites

Using IR-spectroscopy, heat capacity experiments, neutron and X-ray diffrac tion, as well as magnetization and resistivity measurements, TbBaCo2O6-delt a samples with different oxygen content and different thermal history are s tudied. It is shown that the structural, magnetic and electrical properties are strongly sensitive to oxygen content and oxygen vacancy ordering. We s ubmit that the first order semiconductor-to-metal phase transition at 340 t o 345 K in this compound is accompanied by oxygen vacancy ordering and shor t-range magnetic ordering, and only at 285 K spontaneous long-range ferrima gnetic ordering occurs.