In this work, the temperature and frequency dependences of the real part of\nthe admittance [r(f, T)] of annealed nanocomposite films containing Co45\nFe45Zr10-based nanoparticles covered with native oxides and embedded in a\ndoped PbZrTiO3 ferroelectric matrix were studied. The nanocomposites\nstudied were deposited by ion sputtering a complex target in a mixed Ar/O2\natmosphere followed by a 15-min annealing process (with steps of 25 K) in air\nin the temperature range of 398 K �£ Ta �£ 573 K. The r(f, T) of the annealed\nsamples was measured in the temperature range of 77 K< Tp< 373 K at\nfrequencies of 50 Hz< f< 1 MHz. The observed r(f, T) dependences confirmed\nthat the annealed samples displayed the effects of negative capacitance\nover the whole frequency and temperature ranges studied because of the\npronounced oxidation of the nanoparticles. The r(f, T) dependences obtained\nare described using an earlier-developed AC hopping conductance model.\nComparisons between experimental and simulation results allow the model\nparameters to be estimated, such as the activation energies of the hopping\nconductance and the lifetimes of the electrons in the nanoparticles.
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