New MoCd₂ phase in film coatings of molybdenum-cadmium system

Abstract

Ion-plasma sputtering and code position of Mo and Cd ultrafine particles have been used for the first time to prepare solid solutions that are alloys with a concentration up to 57.3 at. % Cd in the film; this confirms the thermal-fluctuation and coalescence of small particles. When coatings are formed by molyb-denum and cadmium nanolayers less than 2 nm in the concentrations range of 60-66 at. % Cd, a new phase was found that was prepared directly in the course of film coating formation; it was identified as the MoCd2 compound with a tetragonal face-centered lattice, with the parameters a = 0.78231 nm and c = 0.77039 nm. X-ray diffraction data for the identification of the intermetallic compound were determined. The unit cell of MoCd2 has been constructed. Upon accumulation in the lattice, cadmium first replaces the molybdenum atom in the center of the unit cell, then another cadmium atom is embedded in the molybdenum lattice, replacing the atom at one of the cube corners and accompanied by a cubicto-tetragonal cell transformation where the cadmium atoms are embedded in pairs on the side faces of the cell in the MoCd2 compound. Thermal stability of the intermetallic compound is limited by 200 ◦ C. Synthesized phase of MoCd 2 has a metallic type of conductivity.

Keywords

• ion-plasma sputtering
• alloys
• coatings
• nanolayers