  The oxide perovskites are a large family of materials with many important
physical properties. Of particular interest has been the fact that this
structure type provides an excellent structural framework for the existence of
superconductivity. The high Tc copper oxides are the most famous examples of
superconducting perovskites, but there are many others [1]. Intermetallic
compounds have been the source of many superconducting materials in the past,
but they have been eclipsed in recent years by the perovskite oxides. The
recent discovery of superconductivity in MgB2 [2] suggests that intermetallic
compounds with simple structure types are worth serious reconsideration as
sources of new superconducting materials. Here we report the observation of
superconductivity at 8 K in the perovskite structure intermetallic compound
MgCNi3, linking what appear at first sight to be mutually exclusive classes of
superconducting materials. The observation of superconductivity in MgCNi3
indicates that MgB2 will not be the only one of its kind within the chemical
paradigm that it suggests for new superconducting materials.
