Low temperature electrical conductance in (FeCoZr)_x(PbZrTiO_3)_((100-x)) nanocomposite films

摘要

In this paper, the temperature and frequency dependences of conductivity, capacity and phase angle of two nanocomposite samples containing Fe_(0.45)Co_(0.45)Zr_(0.10) - based nanoparticles embedded in a doped PbZrTiO_3 ferroelectric matrix were studied. AC measurements have been performed for the low temperatures (15 K ≤ T_p) and within frequency range 50 Hz - 1 MHz. The nanocomposites studied were deposited by ion beam sputtering with use of different synthesis atmosphere in a vacuum chamber. The samples were subdued by a 15-min annealing in air in the temperatures of T_(A1) = 698 K and T_(A2) = 623 K. It was found that for the nanocomposite sample produced using low oxygen content in the synthesis atmosphere (x_1 = 57.6 at.%) negative values of phase angle θ occur, which indicates capacitive type of conduction in the material. We can also notice the strong rapid frequency and temperature depndences of conductivity for this sample. It can be related with hopping carrier transport in the nanocomposite. For the nanocomposite sample with x_2 = 57.6 at.%, which was produced using high oxygen content in the synthesis atmosphere we can observe occurrence of positive values of θ for frequencies f> 5×10~4 Hz. It can be related with the aditional oxidation of Fe_(0.45)Co_(0.45)Zr_(0.10) nanoparticles during the annealing process (potential barriers surround nanoparticles). The type of carrier transport in the nanocomposite samples is defined as hopping.