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The purpose of this work was to obtain an elastic composite material from polymer powders (polyurethane and polypropylene) with the addition of BaTiO3 until 35% with tailored dielectric and piezoelectric features. The filament extruded from the composite material was very elastic but had good features to be used for 3D printing applications. It was technically demonstrated that the 3D thermal deposition of composite filament with 35% BaTiO3 was a convenient process for achieving tailored architectures to be used as devices with functionality as piezoelectric sensors. Finally, the functionality of such 3D printable flexible piezoelectric devices with energy harvesting features was demonstrated, which can be used in various biomedical devices (as wearable electronics or intelligent prosthesis), generating enough energy to make such devices completely autonomous only by exploiting body movements at variable low frequencies.

The aim of this study was to identify representative types of compromising electromagnetic emissions, vulnerabilities and exposure conditions, which represent a potential emission security risk (EMSEC) for information systems. The results obtained can be the basis for the following studies aimed at estimating the EMSEC risk levels materialized in attenuation levels and frequency ranges for the shielded enclosure and electrical filters, respectively the development and testing of electrical EMSEC protection devices that can be integrated in the shielded enclosure.

In this paper, the obtaining and characterization of five experimental models of novel polymer composite materials with ferrite nano-powder are presented. The composites were obtained by mechanically mixing two components and pressing the obtained mixture on a hot plate press. The ferrite powders were obtained by an innovative economic co-precipitation route. The characterization of these composites consisted of physical and thermal properties: hydrostatic density, scanning electron microscopy (SEM), and TG DSC thermal analyses, along with functional electromagnetic tests in order to demonstrate the functionality of these materials as electromagnetic shields (magnetic permeability, dielectric characteristics, and shielding effectiveness). The purpose of this work was to obtain a flexible composite material, applicable to any type of architecture for the electrical and automotive industry, necessary for protection against electromagnetic interference. The results demonstrated the efficiency of such materials at lower frequencies, but also in the microwave domain, with higher thermal stability and lifetime.

The ferroelectric solid solutions described by a general formula 0.98Pb(Zr1-xTix)O3 – 0.02La(Fe3+0.5, Nb5+0.5)O3 have been obtained by solid state reaction technique, where x assumes the following values: 0.42, 0.48 and 0.58. The structure of these ferroelectric compositions has been investigated in detail using X-ray diffraction analysis (XRD) and Scanning Electron Microscopy (SEM). The results obtained by XRD have evidenced that all obtained samples have a perovskite structure. The influence of the sintering temperature on the degree of incorporation of the elements in the solid solution have been studied too. The dielectric and piezoelectric constants have been determined and the influence of temperature on obtained values are presented and discussed. The performed experimental results have pointed out that the materials are characterized by a high anisotropy. Furthermore, the obtained values of the electromechanical coupling factor (kp) is situated between 0.40÷0.65 depending on the composition and the sintering temperature too.

The influence of the sintering temperature on the structure and on the hysteresis loops of Fe3+ doped Pb(ZrxTi1-x)O3 system has been investigated. Three compositions have been selected in the following mode: one in rhombohedral region, one in MPB region and one in tetragonal region have been obtained by solid state reaction technique. Sintering has been carried out at 12000C and 12500C respectively. The nature of the phases has been investigated in detail using X-ray diffraction analysis (XRD). All the sintered samples reveal a perovskite type structure. The surfaces have been lapped and metalized in order to obtaine the hysteresis loops at room temperature. The results showed a similar behaviour with “hard” PZT ceramics.

In the present paper (1-x)Pb (Zr1-yTiy)O3 – xPb (Mn1/3Sb2/3)O3 – z at%E system, with E = Pr3+, Nd5+ and Gd3+ where x = 0.12; y = 0.48; z = 0 and 0.02 ceramic synthesized by solid state reaction technique is analysed. The investigation aims studying of the effect of dopants on the dielectric and piezoelectric properties of such piezoelectric ceramic. The prepared powders have been uniaxially pressed into discs with diameter of 10 – 12 mm and thickness of 1.2 mm. Sintering has been carried out in air atmosphere at temperatures of 1150°C and 1200°C, respectively, for 2 hours each, followed by a controlled cooling at a rate of 200°C /h. The piezoelectric properties have been investigated after a suitable preparation, including polishing, metallization. The structure of the samples has been determined by X-ray diffractometry (XRD), while the morphology and grains size have been investigated by the scanning electron microscopy (SEM). The piezoelectric properties have been studied by the resonance - antiresonance method. XRD analysis reveals a perovskite tetragonal structure and, as expected for ceramic materials, SEM analysis indicates that the average grain size increases as sintering temperature increases. The dielectric and piezoelectric properties have been determined measuring the ceramic discs, and properties, as dielectric permittivity (εr), dielectric loss (tg δ), and the electromechanical coupling factor (kp) have been obtained. The acquired results indicate a significant effect of the dopants on the dielectric and piezoelectric properties of such materials.

In this paper, some compositions described by the general formula Pb(ZrxTi1-x)0.99Fe0.01O3 have been considered and investigated. The compositions considered have been obtained by solid state reaction technique, where x corresponds to 0.42, 0.52 and 0.58. Sintering has been performed for 2 hours at temperatures between 1100oC and 1250oC. The influence of the sintering temperature on the microstructure and on the hysteresis loops of Fe3+ doped Pb(ZrxTi1-x)O3 system has been investigated. The crystallographic phase and microstucture of the sintered compositions have been studied in detail using X-ray diffraction analysis (XRD) and Scanning Electron Microscopy (SEM). The experimental results obtained by XRD have revealed that all the sintered samples have a perovskite structure. In order to correlate the behavior of the sintered materials to their microscopic structure, the domain structures have been defined by SEM. The dielectric properties, as relative dielectric permittivity (εr) and dielectric loss (tan δ) have been measured. The hysteresis loops at room temperature of all un-poled sintered compositions reveal a similar behaviour with “hard” PZT ceramics. The piezoelectric properties like electromechanical coupling factor (kp) have been investigated after polarization.

0.88Pb(Zr0.52Ti0.48)O3 – 0.12Pb(Mn1/3Sb2/3)O3 – 0,02 at%E piezoelectric ceramics, with E = Pr3+ were synthesized by using a conventional method, namely a solid state reaction technique. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) were employed for the structural and microstructural investigations. Piezoelectric methods were used for the dielectric and piezoelectric properties determination. The results of XRD show a perovskite structure and XRD patterns, indexing on a tetragonal cell structure, was carried out for the most common phases. The SEM micrographs of the sintered compositions reveal a homogenous structure with a sharp or rounded grain boundary. The modified PZT ceramic presents still superior piezoelectric properties. Based on the results obtained, one can conclude that the analysed piezoelectric ceramics are useful for device applications.

The concept of more electrical aircraft architecture requires new magnetic materials, with improved magnetic and electrical properties. The paper investigates the soft magnetic materials based on FeCo/Al2O3 core-shell nanoparticles, synthesized by sol-gel technique. These nanomaterials combines the high saturation magnetisation of FeCo compound with the increased resistivity of Al2O3 and allow the decreasing of time-dependent magnetic losses for the bulk sized components, compared with the currently available Fe-Si alloys, used as metallic punched sheets for the building of the magnetic cores in electrical machines. The main physical characteristics of the FeCo/Al2O3 prepared nanomaterials are: saturation magnetisation in the range of 136–213 emu/g, coercivity around 24.5 kA/m (320 Oe) and electrical resistivities of order of 1014 Ω·m.

The character of the original paper is to provide electromagnetic radiation absorbing material that attenuation characteristics of the electromagnetic field very good, as compared to the absorbent materials studied to date. This paper presents results of research on processing, characterization and behavior of composite materials based on silicone rubber used for electromagnetic shielding. In this work silicone rubbers is reinforced with magnetic fillers (iron silicon). The obtaining of composite materials was with the aid of a doctor blade technique. Doctor blade technique is a coating technique widely used for producing thin films on large area surfaces. The samples were processed in the laboratory using a plated nettling (PN), that was impregnated with a silicone rubber based composite containing powder of iron silicon (SI). Were achieved measurements of the both parts of the materials obtaining. These have shown an electromagnetic shielding effectiveness the order of 3.35-41.62 dB (white face) and 3.53-41.42 dB (gray face), in 1-18 GHz frequency range according to SR EN 50 147-1:1999. The paper tries to identify an absorbent material with the ability to protect human beings of electromagnetic radiation that surround us every day and every moment. With the exponential increase in development of commercial, aerospace, military and scientific electronic devices in modern society, electromagnetic radiation is becoming the fourth public pollution after the air, water and noise ones.

The RF circuits are difficult to be miniaturized without compromises concerning the technical performances. The inductors and antennas are the major constraints for systems miniaturization, due to the lack of magnetic materials with adequate high frequency properties. The paper presents novel Co-based magnetic nanostructured materials, with improved characteristics which recommend them as potential candidates for transformers and inductors in electronic components: higher level for saturation magnetisation and electric resistivity in comparison with commercial ferrites. The magnetic nanocomposites are prepared by sol-gel route and consist on Co magnetic nanocrystallites, arranged in a crystalline matrix (silicates, for example). The main physical characteristics of the Co/SiO2 nanopowders are developed after appropriate calcination and annealing, being dependent on the SiO2 amount and on the thermal treatment parameters: saturation magnetisation Ms = 81.7 – 130.4 emu/g, coercivity Hc = 21.7 – 26.9 kA/m (273 - 338 Oe) and increased resistivities for the sintered samples, due to the presence of the SiO2 layers.

ZnO based surge protective devices have been made and characterized both morphological (SEM microscopy and interferometry) and electrical (U/I characteristic and dielectric spectroscopy). SEM microscopy analyzes revealed that the disks of metal oxides sintered at 12000C present a homogeneous distribution of ZnO grains, without pores and well-defined intergranular limits. It was also found that Ag electrodes (applied by Ag paste to 650°C) are well anchored in the structure of the sintered material. The interferometry measurements revealed that the sintered material surface roughness ranges within ± 3μm. The electrical measurements revealed that the threshold voltage of the achieved devices is proportional to the thickness of the disks of approximately 156V / mm. Reverse currents, measured at 0.8 of the threshold voltage were between 0.28 and 0.31mA. Also, the measurements of dielectric spectroscopy revealed that the dielectric loss is highly dependent on frequency, respectively about 0.15 at 40 Hz and decreases exponentially to 0.019 at 10 kHz.

This paper presents the results of experimental determinations concerning electromagnetic field attenuation in materials containing micro-particles of ashes pyrite in their structure. To know the effect of shielding effectiveness of electromagnetic field electromagnetic absorbents were performed by transmission measurements of attenuation in the frequency range 1-18 GHz. The goal of present paper consits in the realization a composit material with polymeric matrix. The synthetic polymeric matrix used at the obtaining composite is represented by a bicomponent silicone elastomer that strengthens itself at the room temperature by means of a poly condensation reaction. The materials obtained in laboratory contain plated nettling like reinforcement material and ashes pyrite as filling agent. The materials were characterized by X-ray diffraction, transmision diminishing carried out and relative permittivity.

There is increasing interest in electromagnetic interference (EMI) shielding due to the serious electromagnetic environment pollution caused by the continuously increased use of the electrical products and electronic devices. Electrical conductivity and EMI shielding efiectiveness (SE) of composite materials made from silicone rubber with carbon powder and ferrite powder have been studied in microwaves and terahertz frequency ranges and the results are presented in this paper. In microwaves range, samples with higher electrical conductivity show a small variation of shielding performance with frequency, whereas the performance of samples with lower conductivity falls away with increasing frequency. It is shown that the variation of attenuation with frequency relates to the conductivity of the material.

The purpose of this paper was to obtain new hybrid composite materials (HCM) with applications in electromagnetic shielding and their characterization using new methods. The paper presents 6 experimental models (EM) of new hybrid composite materials (HCM) with applications in the electromagnetic shielding and their characterization using new methods. EMs were obtained by extrusion and melt injection, with different ratios of HDPE/hybrid NiFe2O4/Ag mixture concentrations: 100/0 - I0; 97/3 - I1; 95/5 - I2; 93/7 - I3; 90/10 - I4 and 80/20 - I5. The characterizations performed within this work are imposed and correlated with the operating conditions of these materials. Thus, we studied the behavior of polymer composite materials with hybrid fillers, under the action of different degradation factors such as ionizing radiation, UV radiation and moisture. Following the tests performed, the experimental model I5, composite with maximum ferrite concentration, i.e. 20 %, was chosen as the optimal variant. It was aimed to identify the degree of degradation of the developed composite materials, as a function of the variation of tan δ with frequency, at different aging/ conditioning cycles. The originality element of the paper consisted in determining the life time remaining of the HCM until the moment it needs to be replaced, by an original method protected of by an invention patent.