In recent decades, the industries have experienced rapid development of various technologies directly or indirectly related to the emission of electromagnetic energy into the environment. The number of emitting technical means in production and in everyday life is increasing. At present, there are different ways, methods and materials to reduce the effects of electromagnetic radiation. The properties of absorbers of electromagnetic radiation (EMR), formed on the basis of domestic natural material of shungite species from the deposit of the mining company "Koksu", Almaty region, are considered. The results of the interaction of EMR with samples of materials of absorbers and the dependence of the transmission coefficients on the angle of incidence of electromagnetic waves (EMW) in the frequency range 5.3-10.6 GHz are obtained. Research in these frequency ranges is crucial and relevant with the development and transition in the future of systems and mobile cellular networks o...

In this study, clay composites were subjected to electromagnetic transmission testing at frequencies in the region of non-ionizing radiation. Specimens were made with partial substitution of clay with different admixtures by mass. Admixtures used were Fly Ash, four different particle sizes and phases of Titanium Dioxide (TiO2), Zinc Ferrite (ZnFe2O4), Maghemite (γ-Fe2O3) and Antimony Tin Oxide (ATO). The additives were thoroughly (chemically, structurally, morphologically) characterized. The replacement percentage was 5 wt.%. Electromagnetic transmission assessment included S21 transmission coefficient measurements for samples with different additives. The lowest transmission was reported for the clay specimens with ATO and Titanium Dioxide, especially at higher frequencies. A decrease in the transmission parameter with increasing specimen thickness was also confirmed.

Halloysite and kaolinite have many similarities in structure, composition, and genesis. Both minerals are dioctahedral 1:1 layer silicates and are hydrated aluminium-silicates. Halloysite has the same theoretical chemical composition as kaolinite except for its higher water content because unit layers in halloysite are separated by a monolayer of water molecules. Halloysite has two forms, a more hydrous form with a single layer of water between the 1:1 layers, which is named halloysite-(10 Å), and a less hydrous form, termed halloysite-(7 Å). The presence or lack of water layers produces different basal spacings in the structure. The ideal unit formula for kaolinite is Al2Si2O5(OH)4 and Al2Si2O5(OH)4·nH2O, where n = 0 for halloysite(7 Å) and n = 2 for halloysite-(10 Å), respectively. Halloysite and kaolinite show variable Fe3+ contents in octahedral positions, and this substitution can be greater in halloysite (up to 12.8% of Fe2O3) than in kaolinite (up to 7% of Fe2O3). Kaolinite u...

This chapter provides an overview of results obtained by a variety of spectroscopic techniques. The most common techniques employed are infrared and Raman spectroscopy, which enable detailed observation of in particular the behaviour of water and OH-groups and the type of H-bonds formed. The inner-surface OH-groups that normally form H-bonds with adjacent layers in the kaolins, form H-bonds with water in the interlayer in halloysite. IES showed that the four inner and inner-surface OH-groups were removed at different temperatures and/or at different rates. A slight increase in the Al 2p binding energy observed in the XPS spectra from kaolinite to halloysite reflects a change in the stacking order due to the interlayer water. The overall shape of the O 1s is indicative of two peaks associated with the oxygen atoms and with the OH-groups. A third, very weak peak was observed associated with interlayer water still present despite the ultrahigh vacuum.

In this paper, we present an efficient method to classify complex electromagnetic materials. This method is based on the directional interaction of incident circularly polarized waves with the materials being tested. The presented method relies on an algorithm that classifies the test materials to one of the following categories: isotropic, chiral, bi-isotropic, symmetric anisotropic or general bianisotropic. The transmitted and reflected fields of right-handed and left-handed circularly polarized waves normally incident from three orthogonal orientations are utilized to determine the reflection/transmission coefficients and complex refractive indices. Both analytical and numerical solutions are used to compute fields of the circularly polarized waves from the arbitrary complex material slab. The complex materials are discriminated accordingly and then classified under an appropriate category. Additionally, new results for material characterization by extracting the scalar/tensorial...

Vermiculite is a clay mineral that is generally used for a wide range of applications such as in agricultural, horticultural and construction industries. This is due to its various properties which include high porosity, lightweight, thermo-insulating, non-toxic and good absorption capacity when exfoliated. The objective of this research was to critically evaluate the fundamental interaction of electromagnetic waves with vermiculite from different source locations and to understand the mechanism of exfoliation in an applied microwave field. When vermiculite minerals are placed under the influence of high electric fields, they expand due to the rapid heating of their interlayer water, which subsequently builds up pressure that pushes apart the silicate structure. The degree of exfoliation is directly related to the intensity of the applied electric field. The principal areas covered in this thesis include: a detailed review of the fundamentals of microwave processing and issues surro...