SOME CHEMICAL AND PHYSICAL PROPERTIES OF QUATERNARY BOROCARBIDES

摘要

The recent discovery of superconductivity (SC) in the quaternary borocarbide system Y-Ni-B-C has opened up a new area of research in SC. SC mainly occurs only for the end members of rare earths (R) and magnetism and SC coexist when R is a magnetic ion (Ho, Er, Tm, and later in Dy). We will discuss and give some new results on the effects of annealing on the impurity phases and on low Fe doping rates on the coexistence between SC and magnetism in materials with R = Ho. Superconductivity has been reported in Y-Pd-B-C system with a T-c (22 to 23 K) higher than the record for bulk intermetallics. The composition and structure of the SC phase(s) is still a topic of controversy that we will briefly discuss, giving new results. (C) 1997 Academic Press. [References: 56]