Chivalrat Masingboon

Giant Dielectric Response in Perovskite-Derivative CaCu3Ti4O12 Prepared by Polymerized Complex Method

Nano-sized powders of CaCu3Ti4O12 (crystallite size of 44, 58 and 71 nm) have been synthesized by a polymerized complex method, followed by calcination the synthesized precursor at 600, 700 and 800°C in air for 8h. The CaCu3Ti4O12 powders were then characterized by XRD, FTIR and SEM. Sintering of the powders was conducted in air at 1100°C for 16h. The XRD results confirmed a typical perovskite CaCu3Ti4O12 structure in all the sintered ceramics, although the presence of a second phase of CaTiO3 was observed in the sample sintered using the powders calcined at 600°C. Microstructure of the sintered CaCu3Ti4O12 ceramics was observed by SEM and the grain size of the materials evaluated with polished using the line intercept method were found to be ~ 10-20 μm. A giant frequency-dependent dielectric constant samples (ε ~10000-60000) with weakly temperature dependence and was observed in the all the samples. The highest dielectric constant of the material was found to be ~60000 (at 140-160°C, 100 Hz) in the sample sintered using the powders calcined at 700°C. The origin of the high permittivity observed in these CaCu3Ti4O12 ceramics is attributed to the Maxwell-Wagner polarization mechanism.

Synthesize, Characterization and Magnetic Properties of Nanoparticle Bismuth Ferrite (BiFeO3) Prepared by a Simple Sol-Gel Route Using Egg White

Nanocrystalline bismuth ferrite (BiFeO3) powders were synthesized by simple sol-gel route using bismuth nitrate, iron nitrate and freshly extracted egg white (ovalbumin) in aqueous medium. In this process, synthesized through solutions of some specific salts led to the formation of nanoparticle BiFeO3 powders (40–95 nm as evident from TEM) at a temperature of 500 and 600°C for 3 h. The synthesized powders were characterized by TG/DTA, XRD, SEM, TEM and VSM. From the VSM result, the magnetization decrease with increasing particle size.

Ni-Cu-Zn ferrite prepared by aloe vera plant extract or egg white

ions at octahedral sites [2]. It was suggested recently that some Zn, Ni and Cu ferrites offer superior magnetic properties depending on certain concentration of Ni, Cu, Zn in the ferrites [3]. The present study reports on the effects of Zn, Ni, and Cu concentrations on the structural and magnetic properties of the ferrites prepared by simple, cost-effective, non-toxic sol-gel methods. In this study, either Zn(NO