Dielectric behavior of nano-structured and bulk Li Ni Zn ferrite samples

• Published in: Journal of magnetism and magnetic materials Vol. 324; no. 19; pp. 2989 - 3001
• Main Authors: Saafan, S.A., Assar, S.T.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.09.2012; Elsevier
• Subjects: AC conductivity; Bulk sampling; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Cross-disciplinary physics: materials science; rheology; Dielectric constant; Dielectric loss; Dielectric loss and relaxation; Dielectric properties of solids and liquids; Dielectrics, piezoelectrics, and ferroelectrics and their properties; Exact sciences and technology; Ferrite; Ferrites; Grain boundaries; Loss factor; Materials science; Materials synthesis; materials processing; Mathematical models; Nanocomposites; Nanomaterials; Nanoparticles; Nanopowders; Nanoscale materials and structures: fabrication and characterization; Nanostructure; Permittivity (dielectric function); Physics; Ferrites; Nanoparticles; Loss factor; Dielectric constant; AC conductivity; Particle size; Frequency dependence; Electrical conductivity; Chemical precipitation; Dielectric properties; Nanostructures; Zinc; Complex impedance; Ferrites spinels; Sintering; Dielectric losses; Semiconductivity; Nickel; Permittivity; Coprecipitation
• ISSN: 0304-8853
• DOI: 10.1016/j.jmmm.2012.04.037

The ac conductivity and dielectric properties of spinel ferrite nanoparticles of Li0.1(Ni1−xZnx)0.8Fe2.1O4 (x=0.0–1.0) prepared by the chemical co-precipitation method were investigated as functions of frequency and temperature by using a complex impedance technique. Parts of the precipitated powders were pressed into a disk-shape and were sintered at 1473K for 2h to increase the particle size to the bulk scale (dimensions >100nm). The ac conductivity of the samples increases with increasing temperature, ensuring the semiconducting behavior of both nano and bulk samples, in agreement with the Koops model to describe heterogeneous structures. The significant decrease in ac conductivity σ′ac, dielectric constant, and dielectric loss of the as-prepared nanosamples compared to their bulk counterparts is correlated to the small size of the grain compared to the grain boundary size. This might be useful for many applications requiring the reduction of eddy current effects. ► Nanosamples of Li0.1(Ni1−xZnx)0.8Fe2.1O4 and their bulk counterparts have been prepared. ► Investigated properties are ac conductivity, dielectric constant and loss tangent. ► An essential decrease in σac in all samples except Ni Zn ferrite is due to incorporation of Li. ► Further decreases in σac and ε′ of nanosamples than the bulk ones are due to the nanosize.