Superconductivity of small particles of titanium oxynitride

Measurements were made of some superconducting parameters of small particles (20--60 nm), granular samples, and pore-free polycrystals of titanium oxynitrides of various compositions (0.76--4.13 mass % [O]). The dependences of the critical temperature, critical magnetic field, penetration depth, coherence length, and Ginzburg-Landau parameter on the oxygen content of the samples were established. It was found that in the case of granular samples the value of the critical temperature was independent of the volume fraction of the oxynitride, particle size, and state of the surface, and it coincided with the onset temperature T/sub co/ for the transition in separate particles. It was concluded that oxygen-free titanium mononitride of strictly stoichiometric composition is a type I superconductor