X-Ray and Electron Microscopic Confirmation of the Existence of the MoCd2 Phase in Film Coatings of the Molybdenum–Cadmium System

Abstract

Using ion-plasma sputtering and the co-precipitation of superdispersed particles of Mo and Cd, solid solutions—alloys with a concentration of up to 57.3 at % Cd in a film—are produced for the first time, which confirms the thermal-fluctuation melting and coalescence of small particles. During the formation of coatings by molybdenum and cadmium nanolayers with a thickness of less than 2 nm in the concentration range 60—66 at % Cd, a new phase identified as MoCd2 is detected; it is obtained directly in the process of film-coating formation and has a tetragonal face-centered cubic lattice with the parameters a = 0.78231 nm and c = 0.77039 nm. Radiographic data for identification of the intermetalloid are determined. The MoCd2 unit cell is constructed. As cadmium accumulates in the lattice, it first replaces the molybdenum atom in the center of the unit cell; then, another cadmium atom becomes embedded in the molybdenum lattice, replacing the atom at one of the cube vertices and this process is accompanied by transformation of the cell type from cubic to tetragonal, where cadmium atoms are embedded pairwise at the side faces of the cell in the MoCd2 compound. The thermal resistance of the intermetalloid is limited by 200°C. The synthesized MoCd2 phase has a conductivity of metallic type.