Magnetic Properties of Pb 2 Sr 2 Eu 1-x Ca x Cu 3 0 8+z Superconductors

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MAGNETIC PROPERTIES OFPb Sr 2Eu1, Ca xCu308+z SUPERCONDUCTORS C.D. NELSON,

V.P. PRATT, JR.

AND P.P VAISHNAVA

Work supported by Center for Fundamental Materials Research of Michigan State University ** Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824-1116 ***GMI Engineering and Mangement Institute, Flint, MI 48504 *

ABSTRACT X-ray diffraction and magnetic measurements using a SQUID magnetometer have been performed on the title compounds for 0 < x < 0.9. For 0 < x < 0.5, we have single phase materials. However, a small percentage of an impurity phase is noticed in the x - 0.7 sample, and the x - 0.9 sample is clearly not a single phase material. The transition temperature, the diamagnetic-shielding effect, and the Meissner-effect increase as x becomes larger. We have obtained, approximately, Hcl < 700 Oe and Hc2 > 800 kOe.

INTRODUCTION Cava et al. [1-3] and Subramanian et al.[4] recently discovered independently a new family of planar copper-oxide superconductors with transition temperatures near 70 K and general formula: Pb2Sr 2ACu3 08+z, where A is a lanthanide, or a mixture of Ln+Sr or Ca. This new many-layered perovskite exhibits the rich substitutional chemistry of the other copper-oxide superconductors and has the usual double CuO 5 pyramidal layers that are separated by SrO-PbO-CuO -PbO-SrO layers. z

In this paper, we report X-ray diffraction studies and magnetic susceptibility measurements on Pb 2Sr2 Eu xCaxCu308+z for 0

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