Magnetoelectric Composites: Modeling and Application
Mirza Bichurin,
Roman Petrov,
Alexander Tatarenko
Issue:
Volume 9, Issue 2, June 2020
Pages:
15-27
Received:
27 February 2020
Accepted:
12 March 2020
Published:
28 April 2020
Abstract: The progress in electronic technology is directly coupled with the advances made in materials science. Within the broad class of materials available today, functional materials provide unique opportunity for developing novel components and devices as their physical and chemical properties. A combination of ferromagnetic and ferroelectric materials provides a new class of functional materials, termed as magnetoelectrics. An overview of modern magnetoelectric composites and examples of the design of electronic devices based on them are presented. The feature of these materials is that their parameters changes under the influence of an external magnetic and electric fields. The behavior of magnetoelectric composites in the wide frequency range is considered. Modeling of ME composites at low frequencies and in the field of electromechanical, ferromagnetic and magnetoacoustic resonances has shown that they can be effectively used to design various electronic devices in a wide frequency range. Nomographs method which can be used to plot the ME parameters versus initial material parameters and component volume fractions is presented. Nomographs can be used for a quick test of ME composites for applications where an approximate answer is appropriate and useful. Examples of ME composites application such as: magnetic field sensors, current sensors, microwave phase shifters, filters, attenuators, isolators are presented.
Abstract: The progress in electronic technology is directly coupled with the advances made in materials science. Within the broad class of materials available today, functional materials provide unique opportunity for developing novel components and devices as their physical and chemical properties. A combination of ferromagnetic and ferroelectric materials ...
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Long-Range Order in the Dislocation Structure of Martensite Crystals
Faina Fedorovna Satdarova
Issue:
Volume 9, Issue 2, June 2020
Pages:
28-34
Received:
16 May 2020
Accepted:
1 June 2020
Published:
17 June 2020
Abstract: Optimal estimation of the diffraction observations over the object reliably detects periodicity in the dislocation structure of martensitic transformation as an exhibition of its wave nature. The period along normal to the slip planes is comparable with the radius of dislocation loops in crystals. The measured degree of one-dimensional long-range order in the arrangement of the loops is close to the upper limit equal to unity. Subject to the theory of metals, the observed structure could be generated by quantum lattice vibrations, which actuate a jump-like phase transition. A simple explanation exists: after a sharp fall in temperature, the excess energy of conduction electrons causes the crystal to expand instantly with the transformation of translational symmetry. Internal shifts of the crystal lattice caused by electron-phonon interactions concurrently trigger the wave process of formation of thin martensitic plates in the surrounding matrix, which are observed in metallography. Based on an in-depth analysis of the dislocation structure of martensite crystals, a physically founded concept is advanced in which the martensitic transformation is a macroscopic quantum phenomenon connected with the symmetry properties of a crystal system in metals.
Abstract: Optimal estimation of the diffraction observations over the object reliably detects periodicity in the dislocation structure of martensitic transformation as an exhibition of its wave nature. The period along normal to the slip planes is comparable with the radius of dislocation loops in crystals. The measured degree of one-dimensional long-range o...
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Thermophysical Characterization of an Insulating Bio-material Based on the Macerate of ''Néré'' (Parkiabiglobosa) Pods and Cow Dung
Djossou Ayihaou Armand,
Adamon Gildas David,
Houngbeme Carlos,
Houngan Comlan Aristide,
Houehanou Ernesto,
Vianou Antoine
Issue:
Volume 9, Issue 2, June 2020
Pages:
35-41
Received:
25 May 2020
Accepted:
17 June 2020
Published:
23 July 2020
Abstract: This work concerns the thermophysical characterization of a bio-eco-material made from cow dung and the macerate of néré pods. To achieve this, chemical tests based on tannin concentration determination of four different solutions of néré pods (60 g.l-1; 120 g.l-1; 180 g.l-1 and 240 g.l-1) were prepared at 100°C, then brought to the boil for 5 minutes. After three different maceration times (6 h; 24 h and 48 h), the analysis of the solutions obtained using a spectrometer made it possible to select the solutions of 120 g.l-1 and 180 g.l-1 which offer best tannin concentrations in 24 hours, necessary for making test pieces. Thermal tests based on thermal effusivity and thermal conductivity measurements were then carried out in transient mode, with hot strip method. In order to compare the thermal performance of developed eco-material with that of ordinary insulators, the thermophysical properties of plywood and plaster were also measured. The results obtained showed that for the two dosages of 120 g.l-1 and 180 g.l-1, the thermal effusivity of eco-insulator varies from 247.732 J.K-1.m-2.s-0,5 to 270.732 J.K-1.m-2.s-0,5 respectively and the thermal conductivity from 0.082 W.m-1.K-1 to 0.080 W.m-1.K-1. For the same dosages, the thermal diffusivity varies from 1.106.10-7 m².s-¹ to 0.881.10-7 m².s-¹ respectively. A comparative study has shown that the eco-material developed and tested offers better insulating power due to its relatively weak thermophysical properties compared to ordinary insulating materials, namely plaster and plywood.
Abstract: This work concerns the thermophysical characterization of a bio-eco-material made from cow dung and the macerate of néré pods. To achieve this, chemical tests based on tannin concentration determination of four different solutions of néré pods (60 g.l-1; 120 g.l-1; 180 g.l-1 and 240 g.l-1) were prepared at 100°C, then brought to the boil for 5 minu...
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