Laser induced structural and transport properties change in Cu–Zn ferrites

The samples were prepared from analar oxides (BDH) using the standard double sintering ceramic technique. X-ray diffraction (XRD) was carried out to assure the formation of the sample in single spinel phase. The effect of Q-switched Nd:YAG laser irradiation with wavelength of 1064 nm on the electrical properties of the prepared samples Cu_1 − x Zn_x Fe₂O₄ (0.1 ≤ x ≤ 0.6) was discussed. The temperature dependence of the polarization and a.c. conductivity was studied in the range (300 K ≤ T ≤ 700 K) at different applied frequencies (10 kHz ≤ f ≤ 4 MHz). The activation energies were calculated at different temperature regions for the unirradiated and irradiated samples. Their values indicate the semi-conducting like behaviour of the sample. Comparison between the ac electrical conductivity, dielectric constant, dielectric loss, for unirradiated and irradiated samples with different Zn concentrations (0.1 ≤ x ≤ 0.6) was performed. Seebeck voltage measurements showed that, the n and p-type conduction act in cooperation with each other. The change in a.c. conductivity is attributed to the creation of lattice vacancies after laser irradiation. The decrease of the a.c. conductivity and the dielectric constant after laser irradiation with 18000 shots may be due to formation of traps, which decrease the number of carriers. The lattice mismatch in the grain boundaries causes a planar array of localized states, being able to capture free carriers. The accumulated charge constitutes an electrostatic barrier impeding carriers from free motion. Thus, it is possible to optimize the conductivity of this type of ferrite material to be used in technological applications at room temperature.