Norlaily Mohd Saiden

Complex dielectric modulus and relaxation response at low microwave frequency region of dielectric ceramic Ba6-3xNd8+2xTi18O54

The desirable characteristics of Ba6-3xNd8+2xTi18O54 include high dielectric constant, low loss tangent, and high quality factor developed a new field for electronic applications. The microwave dielectric properties of Ba6-3xNd8+2xTi18O54, with x = 0.15 ceramics at different sintering temperatures (600–1300°C) were investigated. The phenomenon of polarization produced by the applied electric field was studied. The dielectric properties with respect to frequency from 1 MHz to 1.5 GHz were measured using Impedance Analyzer, and the results were compared and analyzed. The highest dielectric permittivity and lowest loss factor were defined among the samples. The complex dielectric modulus was evaluated from the measured parameters of dielectric measurement in the same frequency range, and used to differentiate the contribution of grain and grain boundary.

Preparation and Characterization of Sr1−xNdxFe12O19 Derived from Steel-Waste Product via Mechanical Alloying

Steel waste product had been used as the main source of raw material in the preparation of permanent magnets ferrites. Steel waste product is an impure material that contains the iron oxide and impurities. The steel waste product is a form of flakes is grinding for several hours to form a fine powder. The iron oxide powder is separated from magnetic and non-magnetic particle using magnetic particle separation. The magnetic particle was again been purified by using the Curie temperature separation technique. The magnetic powder was carried out from the purification and oxidize at 500 °C for 6 hours at 2 °C/ mins to form the hematite, Fe2O3, used as a raw powder to prepare SrFe12O19. Microstructure of Nd-doped strontium ferrites, Sr1-xNdxFe12O19, with x = 0.0, 0.1, 0.2, 0.3, 0.4 and 0.5, were prepared through a mechanical alloying technique. Several characterizations have been done, such as X-ray Diffraction (XRD) and Field emission scanning electron microscopy (FESEM). The magnetic properties of coercivity (Hc) and the energy product BHmax of samples are carried out. The magnetic properties of samples were investigated with an expectation of enhancing the magnetic properties by substitutions of Nd3+ ions on Fe3+ ion basis sites. The saturation magnetization Ms revealed magnetic behavior with respect to Nd3+ doping concentration, showing a decrease. The coercivity Hc increased with increasing Nd3+ doping concentration.

Thermal and frequency stability of dielectric ceramic Ba6-3xNd8+2xTi18O54 (x=0.15, 0.25)

A new dielectric material, barium neodymium titanate (BNT) ceramic can provide good thermal and frequency stability on the dielectric properties. The synthesis of BNT ceramics with x=0.15 and 0.25 was carried out using wet solid state method. The ceramics were characterized by X-ray diffraction to identify the phase. The shifting of XRD peaks revealed higher content of neodymium ions inside the compound. Surface morphology of the ceramics was determined using FESEM. Different compositions influenced the grain growth of the ceramics. BNT ceramics with higher neodymium content showed higher porosity, and higher resistance to shrinkage. The dielectric properties at low frequency from 40 Hz to 1 MHz were measured using Impedance Analyzer. The polarization effect inside the material was discussed and compared. BNT ceramics with x=0.15 has higher dielectric constant. These BNT ceramics showed frequency and thermal stability with respect to the dielectric constant.