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.

Dielectric Characterization and Modeling of Composite Materials Based on Epoxy Resin/Black Iron Oxide/Titanates in Several Frequency Ranges


 In the same matrix of epoxy resin, Fe3O4 powder was evenly mixed with one of two titanate powders, CaTiO3 or SrTiO3. The dielectric properties of these blends were evaluated using the measurement technique of time domain spectroscopy. During this work, low-frequency analyses (DC - 300 MHz) were carried out, mainly focusing on the static permittivity and conductivity properties as a function of titanate concentrations. The results allowed us to confirm the validity and effectiveness of the modified Lichtenecker Laws (MLL). Significant agreement can be shown between the MLL-calculated and experimentally determined permittivity values for ternary combinations. The perspective of this research lies in the production of new materials for use in the field of telecommunications and in particular for microelectronic components.

Dielectric Behavior Investigation of Composite Materials Based on Epoxy Resin / Fe3O4 / CaTiO3, SrTiO3 Using Mixture Laws

A ternary composite's dielectric modeling as a binary one

The work developed in this article consists of the optimization of the modified Lichtenecker model (MLL) and its validation using experimental data from a time domain reflectometry measurement bench. This model will allow the prediction of the dielectric behavior of ternary mixtures and the simplification of ternary model into that of the binary. The practical results taken for this type of composites concern the evolution of the permittivity over a broad frequency spectrum that ranges from DC to 10GHz. The use of the modified Lichtenecker law allowed us to find the shape factor which by different methods of approximation we managed to optimize this theoretical model. This performance was confirmed by the low relative errors obtained. The focus of this research is on the use of these materials in the downsizing of telecommunications and microelectronics components.

The principal subject of the present article is the study of the phenomenon of dispersion as well as the effect of the concentration of strontium titanate (SrTiO3) and carbon black on the complex p...

Study of the relaxation and resonance behaviors of ternary composites: Epoxy–strontium titanate–carbon black:

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 (MnO 2 ) 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 (MnO 2 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 (MnO 2 ) 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.

Dielectric behavior of a quaternary composite (RE, BT, MnO2, CaO) in the band (DC–2 GHz)

In this paper, we have proposed three types of taper structures called L.C.C (L : linear, C : concave and C : convex) that form at the end of the optical fibers in order to use them for detection in order to improve the formation of evanescence waves on the surface of the fiber We studied on these three types of structure four materials such as: silicon (Si), glass (SiO2), sapphire (Al2O3) and zircon (ZrSiO4) with refractive indices 1.45, 1.52, 1.77 and 1.92, respectively. First, three tapered shaped structures were designed with a length ‘L’ set at 50 μm and a diameter ‘D’ equal to 10 μm. Then, they shrink to 1 μm in diameter ‘from the end of their structures. We used an optical DC source with a power amplitude of 1 Vm−1. We also simulated these ‘L.C.C’ structures with the OptiFDTD simulation software, which is based on the finite difference time domain (FDTD) method. The numerical results obtained are: the transverse electric (TE) distribution of the evanescent wave (EW) and the leakage wave (LW) from the left end of the tip for the proposed taper structures. Finally, we presented the transmission. The results obtained showed that the geometric shape (such as the shape of the taper structure) and the type of material (such as the refractive index ‘n’) are very important. These play a crucial role in creating the evanescent waves in the tapered region of the sensor for sensing, which can be used to demonstrate the application of the desired sensor.

Mounir Bouchaour

Papers

Dielectric behavior of a quaternary composite (RE, BT, MnO2, CaO) in the band (DC–2 GHz)

Study and simulation of the effects of geometry and materials on the detection potential of tapered fiber sensors