Präparation und Supraleitungseigenschaften von Niobnitrid sowie Niobnitrid mit Titan-, Zirkon- und Tantalzusatz

Abstract

A description of preparation for samples of niobium nitride without and with admixtures of titanium, zirconium and tantalum by diffusion of nitrogen under pressure into niobium wires without and with admixtures of titanium, zirconium and tantalum respectively, is given. For samples of pure niobium nitride with different compositions the influence of the nitrogen content on the transition temperature to superconductivity has been investigated with the result of a transition temperature not exceeding 16.5 °K even for the stoichiometric composition NbN. This is in contrary to other authors. For diffusion wires of the systems (Nb-Ti)N _x , (Nb-Zr)N _x and (Nb-Ta)N _x the critical temperature, lattice parameter and nitrogen content as a function of the admixture of titanium, zirconium and tantalum respectively, are given. For the first time the magnetisation curve of niobium nitride has been measured showing the behaviour of type II superconductors. Concerning the kinetics of formation of niobium nitride by diffusion the nitrogen content is increasing for constant nitrogen pressure with raising temperature of diffusion, but is decreasing in the high temperature region.