Effect of Ca substitution on some physical properties of nano-structured and bulk Ni-ferrite samples

• Published in: Journal of magnetism and magnetic materials Vol. 374; pp. 264 - 272
• Main Authors: Assar, S.T., Abosheiasha, H.F.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15.01.2015
• Subjects: Bulk sampling; Cation distribution; Cations; DC electrical conductivity; Direct current; Ferrites; Fourier transforms; Infrared spectroscopy; Nanoparticles; Nanostructure; Saturation magnetization; Sintering; Thermal diffusivity; Ferrites; Nanoparticles; Cation distribution; Thermal diffusivity; DC electrical conductivity; Saturation magnetization
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2014.08.011

Nanoparticles of Ni1−xCaxFe2O4 (x=0.0, 0.02, 0.04, 0.06 and 0.10) were prepared by citrate precursor method. A part of these samples was sintered at 600°C for 2h in order to keep the particles within the nano-size while the other part was sintered at 1000°C to let the particles to grow to the bulk size. The effect of Ca2+ ion substitution in nickel ferrite on some structural, magnetic, electrical and thermal properties was investigated. All samples were characterized by using X-ray diffraction (XRD), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR) and vibrating sample magnetometer (VSM). A two probe method was used to measure the dc electrical conductivity whereas the photoacoustic (PA) technique was used to determine the thermal diffusivity of the samples. To interpret different experimental results for nano and bulk samples some cation distributions were assumed based on the VSM and XRD data. These suggested cation distributions give logical explanations for other experimental results such as the observed values of the absorption bands in FTIR spectra and the dc conductivity results. Finally, in the thermal measurements it was found that increasing the Ca2+ ion content causes a decrease in the thermal diffusivity of both nano and bulk samples. The explanation of this behavior is ascribed to the phonon-phonon scattering. •The physical properties of both nano and bulk samples of Ni-Ca ferrites were investigated.•Cation distribution plays a vital role in tailoring the physical properties of all the samples.•The dc conductivity of the nanosamples is higher than their bulk counterparts.•Increasing Ca2+ content enhances Ms, Mr, and σdc of the bulk samples over their nanocounterparts.•The behavior of thermal diffusivity of the samples attributed to the phonon-phonon scattering.