MAGNETIC PHASE-TRANSITIONS AND STRUCTURAL DEFICIENCIES IN SUPERCONDUCTING Y-NI-B-C

Samples of the composition YNi2BxC with 1 less than or equal to x less than or equal to 2 are prepared on a powder-metallurgical route at 13 00 degrees C. This procedure yields specimens with magnetic transition s between 11 K and 24 K and boron deficiencies as compared to the idea l stoichiometry YNi2B2C. Measurements of the magnetization in combinat ion with chemical analysis and electron microprobe analyzer measuremen ts indicate a correlation between the onset transition temperatures T- c and the boron deficiencies in the phase YNi2BxC. Two transitions at 12K less than or equal to T less than or equal to 15.6K and 16K less t han or equal to T less than or equal to 24K are clearly distinguished. (C) 1997 Elsevier Science B.V.