No abstract

No abstract

No abstract

The purpose of this article is to study the dielectric dispersion of two different ternary composites made of epoxy resin (RE), black iron oxide (Fe3O4) with one of the two titanates (calcium titanate (CaTiO3) or strontium (SrTiO3)) on several frequency bands. Additionally, the effect of the two titanates and the (Fe3O4) on the permittivity and conductivity of these ternary composites is investigated. These composite materials were characterized using time domain spectroscopy (TDS). The inclusion of the two titanates increased the real permittivity and conductivity of the two composites, shifting the resonance frequency (ƒR) towards the low frequency range and causing the opposite phenomenon for the static permittivity (ε s). The frequency dispersion behavior model for the complex permittivity has been proposed to improve the effectiveness of the predictive frequency model through a better choice of the damping factor and to bring theoretical and experimental findings closer together. Comparing these data shows that the proposed model is applicable to ternary combinations with high accuracy. The values of the quality factor (Q) obtained are encouraging in microwave applications. These composite materials witch containing CaTiO3 and SrTiO3 inclusions have contributed to the development of dielectric permittivity that suits very well frequency communication systems.

The main objective of this paper is to study the dielectric behavior of a quaternary composite, made from a mixture of barium titanate (BT), manganese dioxide (MnO2) and calcium oxide (CaO) in the same epoxy resin matrix (RE) maintained at 70% by volume fraction, while those of the other constituents are variable and completing each other in a way to achieve the remaining proportion, i.e. 30%. Random mixtures are made at room temperature and under atmospheric pressure. A dielectric characterization of this mixture type was performed by time-domain spectroscopy (TDS) over a frequency wide band (DC–2 GHz). This has been carried out to illustrate the effect of two oxides (MnO2 and CaO) simultaneously at low frequency (500 MHz), in the presence of (BT), on the composite dielectric behavior. This has led consequently to make a comparison between the present acquired results and those of the ternary composite, where (MnO2) and (CaO) act separately. The results obtained so far in this study allowed us to check the validity of the modified Lichtenecker law (MLL)-based predictive model in the quaternary composite case. The interest of this study lies on applications of these materials in microelectronics circuits and absorber materials in telecommunication domain.

No abstract

The goal of this paper is to study the dielectric behavior, in the ternary composites microwave domain, and simplifying ternaries models into binaries ones using time domain spectroscopy. We worked on three ternary composites made of epoxy resin (Re), manganese dioxide (MnO2) and one of three different titanates (XT): barium titanate (BT), calcium titanate (CT) or magnesium titanate (MT). These composites samples dielectric behavior is inspected over a frequency range from DC to 5 GHz. This aims to optimize the predictive modified Lichtenecker's law model (MLL) through a better smoothing shape factor making theoretical and experimental results very close to each other. The comparison between these results shows that the MLL model is pertinent for ternary mixtures (Re-XT-MnO2) with an appreciable accuracy degree. Another numerical approach applied to the Re-[Re-XT-MnO2] mixtures using a binary mixture model equivalent to the previous ternary one based on a simplified MLL expression and preserving the same mixture constituents. This model results are in good agreement not only with ternaries ones being modeled with this law but also with other modeling laws appreciated with binary composites. This study interest lies on these materials application in the telecommunications components miniaturization and in microwave electronic applications.

No abstract