Laered composite hydrogenated films of zirconium and niobium: method of production and control of properties by thermopower method

Abstract

In this work, to obtain layered materials with the inclusion of hydrogen, Nb/Zr films with different numbers of layers from 50 to 100 were used. The films were sputtered onto a silicon substrate using the vacuum-magnetron method in a specialized installation. The film thickness was varied from 10 to 50 nm. The resulting material was hydrogenated with protons on a TPU electrostatic generator with an energy of up to 1,2 MeV. The optimal modes for deposition of nano-sized metal multilayer Zr/Nb systems have been determined: for a Zr target, the specific power of the sputtering system is 37,9 W/cm2, for a Nb target — 26,4 W/cm2. A coating with clear boundaries between the individual layers of zirconium and niobium was obtained. It is shown that the optimal modes for studying nano-sized Zr/Nb layers are pressure 700 Pa, power 40 W, frequency 2 kHz, plasma fill factor 12,5 % for coatings with a thickness of individual layers of 100 nm. For coatings with individual layer thicknesses from 10 to 50 nm, the optimal pressure is 650 Pa, power 40 W, frequency 1 kHz. To control properties, the thermopower method is used. It was revealed that after proton irradiation there is an intensive accumulation of hydrogen atoms near the interfaces, which entails a change in the thermopower up to an inversion of its sign. The hydrogen distribution is predominantly bimodal, with local maxima in hydrogen concentration observed at the Nb/Zr interface, and the accumulation at the Zr/Nb interface is significantly lower. Hydrogen localization near the interfaces occurs predominantly in the vicinity of zirconium.