| The first part of this dissertation discusses the structural and physical property changes by the isomorphous substitution for the cations and the anion in the YBa{dollar}sb2{dollar}Cu{dollar}sb3{dollar}O{dollar}sb{lcub}rm 7-x{rcub}{dollar} type superconductors. The low temperatures ({dollar}<{dollar}300{dollar}spcirc{dollar}C) synthesis approach using ZnF{dollar}sb2{dollar} as a source of F{dollar}sp{lcub}-{rcub}{dollar} successfully displaces O{dollar}sp{lcub}2-{rcub}{dollar} in YBa{dollar}sb2{dollar}Cu{dollar}sb3{dollar}O{dollar}sb{lcub}rm 7-x{rcub}{dollar}. The fluorinated 123-materials are semiconducting. The grainboundary area in a 123-pellet is doped more heavily by F than the inside of the grainboundary area that remains superconducting with T{dollar}sb{lcub}rm c{rcub}{dollar} of 90 K. The ordering phenomena are studied in LnBaCaCu{dollar}sb3{dollar}O{dollar}sb{lcub}rm 7-x{rcub}{dollar} (Ln = La, Nd, and Pr). Regardless of their electrical properties, supercell reflections that double all the axes of the basic 123 type unit cell are observed in the electron diffraction patterns. From the single-crystal X-ray diffraction and electron diffraction patterns twinning is deduced due to an interchange between the a-axis and c-axis. Substitution of Cu by the transition metal elements having various valence states and ionic sizes (Ti, V, Zr, Nb, Mo, Hf, W) are studied in LaBa{dollar}sb2{dollar}Cu{dollar}sb3{dollar}O{dollar}sb{lcub}rm 7-x{rcub}{dollar}.; In the second part of the work are discussed the synthesis and characterization of some superconducting and non-superconducting compounds in Tl-Ba/Ca-Cu-O, Tl-Sr/Ca-Cu-O, Pb-Sr/Ca-Cu-O, and Pb-Sr-Cu-Co-O systems. The two compounds TlSr{dollar}sb2{dollar}CuO{dollar}sb5{dollar} and (Pb{dollar}sb{lcub}0.63{rcub}{dollar}Cu{dollar}sb{lcub}0.37{rcub}{dollar})Sr{dollar}sb2{dollar}CoO{dollar}sb5{dollar} are isostructural, space group P4/mmm, a = {dollar}sim{dollar}3.7A, b = {dollar}sim{dollar}9A. The thermal displacements of the atoms in the plane at z = 0 are discussed. The tetragonal compound (Pb{dollar}sb{lcub}0.63{rcub}{dollar}Cu{dollar}sb{lcub}0.37{rcub}{dollar})Sr{dollar}sb2{dollar}CoO{dollar}sb5{dollar} is stable at a temperature above 960{dollar}spcirc{dollar}C, and can be formed only when the transition element (Fe or Co) is added to the system Pb-Sr-Cu-O. This tetragonal phase decomposes to a hexagonal phase Sr{dollar}sb5{dollar}Pb{dollar}sb3{dollar}(Cu,Co){dollar}sb{lcub}rm x{rcub}{dollar}O{dollar}sb{lcub}11+delta{rcub}{dollar}, space group P{dollar}bar 6{dollar}2m, a = 10.07A, c = 3.54A, and to other unidentified impurity phases below 960{dollar}spcirc{dollar}C.; In the last part of the dissertation the crystal structure and physical properties of a layer structure compound Y{dollar}sb2{dollar}SrCuFeO{dollar}sb{lcub}6.5{rcub}{dollar}, space group Ibam, Z = 4, a = 5.40A, b = 10.69A, and c = 20.22A are determined. Y{dollar}sb2{dollar}SrCuFeO{dollar}sb{lcub}6.5{rcub}{dollar} is semiconducting and shows a 3-dimensional antiferromagnetic ordering transition at about 287 K. The Cu and Fe cations randomly occupy slightly distorted pyramids, which share the apical oxygen atoms and form a two-dimensional slab perpendicular to the c-axis. Double Y{dollar}sp{lcub}3+{rcub}{dollar} layers separate the double-pyramidal layers; they are in 7-fold coordination to oxygen ions that form a deficient fluorite type cubic environment. |
