Superconducting composition based on lanthanum, copper, oxygen, a halogen and, possibly, an alkaline earth and its preparation

摘要

The invention relates to superconducting compositions based on lanthanum, copper, oxygen, a halogen and, possibly, an alkaline earth; these compositions are characterised in that the halogen is present in the crystallographic unit cell of the said composition, in that they have a superconducting volume of at least 20% measured at 1 Oe and at 6 K, as well as metallic behaviour at a temperature above the transition temperature of the said composition. The halogen is more particularly fluorine. These compositions are obtained following a halogenation treatment at a temperature below 350 DEG C. <IMAGE>