Preparation, Superconducting and Normal State Transport Properties of Granular, n-Doped Ln2-xCexCuO4-δ, Ln=Nd, Sm

Abstract
We report on superconducting and normal state transport properties of the electron-doped cuprates Ln2-x Ce x CuO4-δ with Ln=Nd, P Sm. Irreversible behaviour of bulk samples after applying a magnetic field at low temperatures is observed. This feature as well as the two step transition in R(T) and the `semiconducting' behaviour of the polycrystalline samples above T c is explained in terms of granularity. Phase-diagrams for both Nd2-x Ce x CuO4-δ and Sm2-x Ce x CuO4-δ are presented. There is evidence for a solubility limit of Ce-ions in Sm2CuO4 within the superconducting concentration range. We show results for the Hall-coefficient, which is negative all over the investigated temperature range. The preparation process has been monitored by means of X-ray analysis and TGA/DTA.