Percolation threshold of granular metal-dielectric nanocomposites (FeCoZr)x(CaF2)1-x produced in atmosphere of argon and oxygen

The paper presents temperature-frequency dependencies of conductivity of the granular metal-dielectric nanocomposites (FeCoZr)x(CaF2)(100-x). A series of nanocomposite samples with a different metallic phase content from range x = 41.3 – 86.1 at.% produced by twosources ion-beam sputtering in mixed atmosphere of argon and oxygen was tested. Analysis of results of temperature dependences of conductivity of the samples with metallic phase content x bellow 81.8 at.% obtained immediately after producing showed that nanocomposites (FeCoZr)x(CaF2)(100-x) exhibit dielectric properties, namely conductivity increases with the increase of measurement temperature. At the metal phase content x = 86,1 at.% inverse relationship of conductivity was observed, which menace that nanocomposite is characterized by metallic type of conductivity. Comparison of the conductivity at LNT (liquid nitrogen temperature) and at room temperature for different content of metallic phase allowed to set the percolation threshold for tested series of samples of nanocomposite (FeCoZr)x(CaF2)(100-x). The change of type of conductivity from dielectric to metallic type takes place with metallic phase content about 82±0.2at.%.