| The influence of composition on DC carrier transport of composite films containing amorphous CoFeZr nanoparticles in amorphous aluminium oxide matrix has been investigated. The films in the range of 3 to 5 mm thick with variable composition were sputtered on single substrate from the compound target in the chamber with argon-oxygen gas mixture. TEM, SEM and Moessbauer spectroscopy have shown that all the studied films of (Co0.45Fe0.45Zr0.10)Õ(Al2O3)1-Õ with 30 at.% < X < 65 at.% revealed structure with distributed fragmented components of amorphous metallic alloy (with dimensions of particles between 6 and 10 nm) and amorphous alumina. The presence of two critical regions for metallic fraction (X1 = 33 - 40 % and X2 = 50 - 55%), where diagram "electric property-composition" exhibit pronounced peculiarities, has been revealed. A qualitative structural model of nanocomposite is offered to explain this behavior. In accordance with the model the first critical region is connected with the delay of percolation threshold due to partial oxidation of metallic nanoparticles during sputtering. The second critical region of composition is ascribed to the formation of percolative net of amorphous metallic nanoparticles in dielectric alumina matrix. |
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