Abstract

• Nickel ferrites, NiFe2O4, were prepared by three different preparation methods; solid state reaction (SSR) method, chemical co-precipitation (CCP) method and auto-combustion (AC) method. XRD technique was used to investigate the crystalline phase formation and to examine the lattice parameters of the samples. From XRD patterns, the samples analogous to cubic structure and the lattice parameters were found with small variation. The average crystallite sizes were obtained as 74.11 nm (solid state reaction method), 85.31 nm (chemical co-precipitation method) and 49.04 nm (auto-combustion method). Morphological features and porosities of the samples were examined by SEM. The samples were made into circular shaped pellets and their humidity sensitive electrical properties were investigated in the relative humidity range of 50 RH% - 99 RH% with the step of 1 RH% for humidity sensor application.