Characterization of highly dispersed bimetallic Ni-Cu alloy particles by ferromagnetic resonance

Nanocomposites of the nominal composition Ni0.4Cu0.6. nSiO(2) (n = 3,6,9,12,15,20) were investigated by means of ferromagnetic resonance (FMR), to study the influence of metal particle composition and size, and of the metal-matrix interaction on the FMR powder spectra. The thermomagnetic investigations (I-ref(exp)-T dependence) revealed that all nanocomposites except n = 20 posses a bimodal metal particle composition. The Ni-rich component with diameter 8-13 nm consists of about Ni0.9Cu0.1 and the Cu-rich component with diameter 5-11 nm of about Ni0.7Cu0.3 alloy particles. In Ni0.4Cu0.6. 20SiO(2) only the Ni-rich component was detected. By spectral simulation the metal-matrix interaction was characterized at 273 and 423 K by compressive and tensile stress, respectively. The change in sign of the strain at 300 K below the reduction temperature points to the high mobility of the alloy.