Characterization and Dielectric Properties of Nanocrystalline NiO-based Electroceramics Prepared by Mechanical Alloying

Subject Areas : journal of New Materials

F. Talatori ¹ , M.J Hadiyan fard ² , R. Amini ³ , M. Alizadeh ⁴

1 - کارشناس ارشد مهندسی مواد (نانومواد)، دانشگاه شیراز.
2 - استاد بخش مهندسی مواد، دانشگاه شیراز.
3 - استادیار دانشکده مهندسی مواد، دانشگاه صنعتی شیراز.
4 - استادیار دانشکده مهندسی مواد، دانشگاه صنعتی شیراز.

Received: 2014-01-04 Accepted : 2014-01-04 Published : 2013-12-22

Keywords: Ceramic Dielectric, Nickel Oxide. Mechanical Alloying, dielectric constant, Nanocrystal,

Abstract :

Recently, due microelectronic technology developments, it is important to improve the electronic properties ceramic dielectrics, for some applications e.g. capacitors. Accordingly, one of these advanced materials that has attracted much attention in recent research is NiO-based ceramics which shows an extraordinarily a range of high dielectric constant. In the present work, for the first time Li_0.05Ni_0.95O ceramic dielectrics were prepared by mechanical alloying. The structure and microstructure of the milled powders were characterized by X-Ray diffraction (XRD) and Scanning Electron Microscopy (SEM) at different milling times. The quantitative analyses of the XRD results were done by the Rietveld refinement. According to the results, by milling operation, nanocrystallization and particles refinement were developed in which the crystallite and particles size of the powders reached to values of about 20 nm to 200 nm, after 24h of milling. In order to improve the dielectric properties, the 24h milled Li_0.05Ni_0.95O powders were mixed with iron oxide (Fe₂O₃) and after sintering process, the morphology of the Li_0.05Fe_0.02Ni_0.93O sample studied by SEM. It revealed that the grains sizes remained in the submicron range. By measuring the dielectric properties of the Li_0.05Fe_0.02Ni_0.93O sample using LCR meter at 120 Hz-200 kHz frequency range, high dielectric constant (about 5000) and relatively low loss (about 0.9) were obtained at 20 kHz  which remained constant up to 200 kHz.