Oxygen content influence in the superconducting and electronic properties of Nd Ce Cu O ceramics

E. NAVARRO; D. JAQUE; J.E. VILLEGAS; J.I. MARTIN; A. SERQUIS; F. PRADO; A. CANEIRO; J. L. VICENT

JOURNAL OF ALLOYS AND COMPOUNDS

ELSEVIER SCIENCE SA

Lugar: Amsterdam; Año: 2001 vol. 323 p. 580 - 583

0925-8388

Superconducting and electronic properties of Nd Ce Cu O ceramic samples have been studied as a function of the oxygen 1.85 0.15 1.01 ycontent. It has been observed that values of oxygen content ‘y’ above those corresponding to the CuO–Cu O equilibrium partial oxygen 2pressure destroy superconductivity. On the other hand, for lower oxygen contents, resistivity and magnetic superconducting transitions arepresent with critical temperature values up to 20 K. The normal state Hall effect has also been measured presenting a negative RHcoefficient in all the samples. For superconducting samples, R is not significantly dependent on the oxygen content value. In addition, the HHall coefficient is almost temperature independent in these samples. It is in contrast with some of the non-superconducting samples wherethe absolute value of R increases as T decreases. These results reveal that, for samples obtained by annealing below the CuO–Cu O H 2equilibrium partial oxygen pressure, the enhancement of superconducting properties as oxygen is reduced is not produced by a change inthe carrier density, pointing then to a structural ordering effect as an explanation.