Superconducting Properties of Rhenium, Ruthenium, and Osmium

Magnetic measurements have been made on the superconducting properties of rhenium, ruthenium, and osmium, and the influence of various methods of specimen preparation and treatment has been studied. In particular the transition temperature of rhenium could be raised by about 1°K above the ideal value, 1.699°K, by grinding or preparing the specimen as a powder. Although rhenium belongs to the transition elements, specimens of ideal superconducting behavior could also readily be prepared. This reinforces the conclusion of previous workers that the nonideal superconducting behavior frequently found in transition metal specimens is not a fundamental property of this group of elements, but a consequence of the metallurgical history of the specimens.