ELECTRICAL-PROPERTIES AND CRYSTAL-STRUCTURES OF THE HOMOLOGOUS SERIESOF OXIDES ND2BA2CAMCENTI2-DELTA-CU2-O11+M+2N (M, N=0 OR 1)(DELTA)

Four oxides belonging to the homologous series with the general formul a Nd2Ba2CamCenTi2-deltaCu2+deltaO11+m+2n were prepared for m, n = 0 or 1. Although all of these oxides have two-dimensional CuO2 planes, the y do not show any superconductivity, only a normal paramagnetic behavi or. Their crystal structures were analyzed by TOF neutron powder diffr action. Nd2Ba2Ti1.908Cu2.092O11 (m = 0, n = 0 and delta = 0.09) is iso morphous with Gd2Ba2Ti2Cu2O11. The structures of the other three oxide s can be derived from that of Nd2Ba2Ti1.908Cu2.092O11. The structure o f Nd2Ba2Ti1.92Cu2.08O12 (m = 1, n = 0 and delta = 0.08) is obtained by the substitution of rock-salt-type (Ca,Nd,Ba)O-(Ca,Nd,Ba)O layers for the (Nd,Ba)O layer. The structure of Nd2Ba2CeTi2Cu2O13 (m = 0, n = 1 and delta = 0) is characterized by the insertion of fluorite-type (Nd, Ce)-O-2-(Nd,Ce) layers in place of the Nd layer, Nd2Ba2CaCeTi2Cu2O14 ( m = 1, n = 1 and delta = 0) results from the alternate substitutions o f rock-salt-type and fluorite-type layers for the (Nd,Ba)O and Nd laye rs, respectively.