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The 110K single phase sample (Bi,Pb)2Sr2Ca2Cu3Oy was prepared by solid state reaction method. The samples were characterized using X-ray powder diffraction, the measurements of resistivity and dc. susceptibility, and the X-ray photoemission spectrum and specific heat measurement and the electron diffraction analysis. The results show that the superconductivity of (Bi,Pb)SrCaCuO system is sensitive to oxygen content like the 1-2-3 phase material. We suppose that different oxygen content leads to the changes of modulated structure and electronic structure and the ratio of Cu3+, and so to great difference in the superconductivity.

In this paper the effect of constituent content on superconductivity and phase in BiPbSbSrCaCuO system is reported. The zero resistance temperature Tce reaches as high as 132K when Sb = 0.1 and Tce is decreased dramatically with increasing either Sb-content or Cu-content in BiPbSbSrCaCuO system while the corresponding phase is changed fundamentally. A orthorhombic cell with a =23.16 A , b =9.48 A , c =6.20 A is proposed for a predominant phase in nominal composition Bi1.6Pb0.4SbxSr2Ca2Cu3Oy (x=0.3–1.0) of non-superconducting system.

A series of samples with different nominal composition have been prepared and their structure, resistivity and a.c. magnetic susceptibility have been investigated. Zero resistance temperature T ce as high as 110.5K and 101K have been reached in the nominal composition Bi 3 Sr 2 Ca 2 Cu 3 O y and Bi 2 Sr 2 Ca 2 Cu 3 O y samples, respectively. A basically single high-T c phase with the nominal composition Bi 2 Sr 2 Ca 6 Cu 7 O y has been obtained. It is suggested that the samples' T ce is chiefly depended upon the grains boundaries.

Results of resistivity, a.c. magnetic susceptibility, Hall effect and superconductivity for single phase Ba 2 YCu 3 O 7− δ are reported. The positive value of Hall constant above T c indicates that the carriers of the sample are hole-like in normal state and its concentration is about 1.1×10 21 cm -3 at room temperature. A large anomaly of R H near T c is observed which may be indicative of granular superconductivity or be related to the intrinsic quality of this class of oxides.

The Raman spectra of a set of samples with nominal composition Ba x Y 1−x CuO 3 (0.005 ⩽ x ⩽ 0.8) which are synthesized under the same condition have been measured. It is observed that the main characters of Raman spectrum are quite different for the two groups of samples with Ba concentration being 0.3 ⩽ x ⩽ 0.8 and 0.005 ⩽ x ⩽ 0.075 respectively. It just coincides with the results two types of phase structures and the difference in superconductivity related to the two ranges of composition. Based on a comprehensive analysis of the results above, the authors suggest that the Raman peak near 605cm -1 likely corresponds to the vibration of CuO 6 octahedra breathing-mode, which play an important role in this system for achieving high transition temperature.

Raman and infrared spectra of YBa 2 Cu 3− x Co x O 7− δ (0.025 ⩽ x ⩽ 0.5) compounds were measured at room temperature. The charateristic Raman band at 636 cm −1 and the characteristic IR band at 1670 cm −1 of the high T c superconductor were found. The Raman band at 636 cm −1 reflects the relation between superconductivity and the strong electron-phonon coupling in CuO chains or CuO planes; and IR band at 1670 cm −1 is interpreted as charge-transfer or exciton band.

Superconductivity transition has been observed by electrical resistance and a.c. magnetic susceptibility measurements in ErBaCuO and YbBaCuO systems. The highest T c ( ϱ =0) is 90.3K for ErBaCuO and 91K for YbBaCuO.

We report the structure and superconductivity of single crystal YBa2Cu3O7−δ. The maximum dimensions of single crystal are 2.5×2.5×1.5 mm3. It is orthorhombic structure with space group Pmmm, cell parameters are a =3.88 A , b =3.82 A , c =11.68 A . The superconducting critical temperature is Tc=91 K. And a resistance anomalous phenomenon is also observed at 280 K.

In this paper, two main phases are found in the Bi2-xPbxCa2Sr2Cu3Oy system One is 4334 phase, another is a new one with cell parameters a =5.09 A , b =5.18 A , and c =36.98 A . The results of ac susceptibility measurements in the Bi2-xPbxCa2Sr2Cu3Oy system there are three superconducting transition at 110K, 95–100K and 65K respectively. As the x is increased from 0.1 to 1.2, the zero resistance temperature (Tce) is raised to 107K (x=0.3-0.5) at first, then is reduced to 64K gradually.

The structure and compositions of phases in the superconducting Y(Yb)-Ba-Cu-O systems with three nominal compositions have been investigated in a transmission microscope (TEM). Based on our improved quantitative microanalysis method, more accurate contents of Y, Yb, Ba and Cu in phases have been obtained simultaneously with the structure determination by electron diffraction. There is no Ba in Y 2 Cu 2 O 5 phase and a little amount of Ba in (Y, Yb) 2 Cu 2 O 5 phase. The more Y 1 Ba 2 Cu 3 O 7 , the better the superconducting property.

Single phase Ba2CeCu3O7.4 was prepared. EXAFS, X-ray diffraction and plasma spectroscopy measurements were performed. A structure model with the cell parameter: a=6.208 A , b=6.232 A and c=8.759 A is proposed based on these experiments. The lack of superconductivity in this system may be caused by the entrance of Ce+4 in Cu-site and the formation of asymmetric [CuO2] plane.