Tantalum superconducting properties

The superconducting properties of Ta films on alumina substrates prepared by atmospheric pressure CVD have recently been reported [55]. Hydrogen reduction of tantalum pentachloride at an unreported temperature gives superconducting a-7a films with r, = 3.3 K and 77, = 11.2 kOe. 

This alloy is produced ir all forms although it is ger erally used in multifilament cables. The alloys are manufactured in both grade 1 and grade 2 types. Grade 2 material has a higher allowable tantalum content, which has no effect on the superconducting properties. A wet-grade niobium-55% titanium alloy is also available that finds application in the aircraft industry. 

The tantalum carbides and silicides and tungsten carbides cited above are used for their hardness, corrosion resistance in hot environment and their semiconducting properties, while niobium alloys (niobium-germanium, niobium-aluminium...) receive much attention for their properties of superconductivity. 

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