Search results for: multiferroic materials

Authors: S. C. Kattimani

Abstract:

This article deals with the analysis of active constrained layer damping (ACLD) of smart multiferroic or magneto-electro-elastic doubly curved shells. The kinematics of deformations of the multiferroic doubly curved shell is described by a layer-wise shear deformation theory. A three-dimensional finite element model of multiferroic shells has been developed taking into account the electro-elastic and magneto-elastic couplings. A simple velocity feedback control law is employed to incorporate the active damping. Influence of layer stacking sequence and boundary conditions on the response of the multiferroic doubly curved shell has been studied. In addition, for the different orientation of the fibers of the constraining layer, the performance of the ACLD treatment has been studied.

Keywords: active constrained layer damping (ACLD), doubly curved shells, magneto-electro-elastic, multiferroic composite, smart structures

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Authors: K. D. Chandrasekhar, H. C. Wu, D. J. Hsieh, B. J. Song, J. -Y. Lin, J. L. Her, L. Z. Deng, M. Gooch, C. W. Chu, H. D. Yang

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Stress-mediated coupling of electrical and magnetic dipoles in a single phase multiferroic is rare. Pb₂MnO₄ belong to multi-piezo crystal class with the space group P⁻42₁

Keywords: multiferroic, multipiezo, Pb₂MnO₄, spin-flip

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Authors: Mohammad Shariq, Davinder Kaur

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A series of multiferroic (BiFeO3)1−x(PbTiO3)x [x= 0, 0.1, 0.2, 0.3, 0.4 and 0.5] solid solution ceramics were synthesised by conventional solid-state reaction method. Well crystalline phase has been optimized at sintering temperature of 950°C for 2 hours. X rays diffraction studies of these ceramics revealed the existence of a morphotropic phase boundary (MPB) region in this system, which exhibits co-existence of rhombohedral and tetragonal phase with a large tetragonality (c/a ratio) in the tetragonal phase region. The average grain size of samples was found to be between 1-1.5 µm. The M-H curve revealed the BiFeO3 (BFO) as antiferromanetic material whereas, induced weak ferromagnetism was observed for (BiFeO3)1−x(PbTiO3)x composites with x=0.1, 0.2, 0.3, 0.4 and 0.5 at temperature of 5 K. The results evidenced the destruction of a space-modulated spin structure in bulk materials, via substituent effects, releasing a latent magnetization locked within the cycloid. Relative to unmodified BiFeO3, modified BiFeO3-PbTiO3 -based ceramics revealed enhancement in the electric-field-induced polarization.

Keywords: BiFeO3)1−x(PbTiO3)x ceramic, multiferroic, SQUID, magnetic properties

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Authors: Ghazala Anjum, Farooq Hussain Bhat, Ravi Kumar

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Multiferroic materials are vital for new application and memory devices, not only because of the presence of multiple types of domains but also as a result of cross correlation between coexisting forms of magnetic and electrical orders. In spite of wide studies done on multiferroic bulk ceramic materials their realization in thin film form is yet limited due to some crucial problems. During the last few years, special attention has been devoted to synthesis of thin films like of BiFeO₃. As they allow direct integration of the material into the device technology. Therefore owing to the process of exploration of new multiferroic thin films, preparation, and characterization of La₀.₈Bi₀.₂Fe₀.₇Mn₀.₃O₃ (LBFMO3) thin film on LaAlO₃ (LAO) substrate with LaNiO₃ (LNO) being the buffer layer has been done. The fact that all the electrical and magnetic properties are closely related to the electronic structure makes it inevitable to study the electronic structure of system under study. Without the knowledge of this, one may never be sure about the mechanism responsible for different properties exhibited by the thin film. Literature review reveals that studies on change in atomic and the hybridization state in multiferroic samples are still insufficient except few. The technique of x-ray absorption (XAS) has made great strides towards the goal of providing such information. It turns out to be a unique signature to a given material. In this milieu, it is time honoured to have the electronic structure study of the elements present in the LBFMO₃ multiferroic thin film on LAO substrate with buffer layer of LNO synthesized by RF sputtering technique. We report the electronic structure studies of well characterized LBFMO3 multiferroic thin film on LAO substrate with LNO as buffer layer using near-edge X-ray absorption fine structure (NEXAFS). Present exploration has been performed to find out the valence state and crystal field symmetry of ions present in the system. NEXAFS data of O K- edge spectra reveals a slight shift in peak position along with growth in intensities of low energy feature. Studies of Mn L₃,₂- edge spectra indicates the presence of Mn³⁺/Mn⁴⁺ network apart from very small contribution from Mn²⁺ ions in the system that substantiates the magnetic properties exhibited by the thin film. Fe L₃,₂- edge spectra along with spectra of reference compound reveals that Fe ions are present in +3 state. Electronic structure and valence state are found to be in accordance with the magnetic properties exhibited by LBFMO/LNO/LAO thin film.

Keywords: magnetic, multiferroic, NEXAFS, x-ray absorption fine structure, XMCD, x-ray magnetic circular dichroism

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Authors: Parul Jain, Jitendra Saha, L. C. Gupta, Satyabrata Patnaik, Ashok K. Ganguli, Ratnamala Chatterjee

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This study shows how sensitively and drastically multiferroic properties of CaMn₇O₁₂ get modified by isovalent Sr-doping, namely, in Ca₁₋ₓSrₓMn₇O₁₂ for x as small as 0.01 and 0.02. CaMn₇O₁₂ is a type-II multiferroic, wherein polarization is caused by magnetic spin ordering. In this report magnetic and ferroelectric properties of Ca₁₋ₓSrₓMn₇O₁₂ (0 ≤ x ≤ 0.1) are investigated. Samples were prepared by wet sol gel technique using their respective nitrates; powders thus obtained were calcined and sintered in optimized conditions. The X-ray diffraction patterns of all samples doped with Sr concentrations in the range (0 ≤ x ≤ 10%) were found to be free from secondary phases. Magnetization versus temperature and magnetization versus field measurements were carried out using Quantum Design SQUID magnetometer. Pyroelectric current measurements were done for finding the polarization in the samples. Findings of the measurements are: (i) increase of Sr-doping in CaMn₇O₁₂ lattice i.e. for x ≤ 0.02, increases the polarization, whereas decreases the magnetization and the coercivity of the samples; (ii) the material with x = 0.02 exhibits ferroelectric polarization Ps which is more than double the Ps in the un-doped material and the magnetization M is reduced to less than half of that of the pure material; remarkably (iii) the modifications in Ps and M are reversed as x increases beyond x = 0.02 and for x = 0.10, Ps is reduced even below that for the pure sample; (iv) there is no visible change of the two magnetic transitions TN1 (90 K) and TN2 (48 K) of the pure material as a function of x. The strong simultaneous variations of Ps and M for x = 0.02 strongly suggest that either a basic modification of the magnetic structure of the material or a significant change of the coupling of P and M or possibly both.

Keywords: ferroelectric, isovalent, multiferroic, polarization, pyroelectric

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Authors: S. Nqayi

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Understanding the structural, electronic, and magnetic properties of nanomaterials is essential for developing next-generation electronic and spintronic devices, contributing to the progress of nanoscience and nanotechnology applications. Multiferroic materials, with intimately coupled ferroic-order parameters, are widely considered to breed fascinating physical properties and provide unique opportunities for the development of next-generation devices, like multistate non-volatile memory. In this study, we are set to investigate the structural, electronic, and magnetic properties of the frustrated Feᴵᴵ/Smⱽᴵ sublattice in relation to the widely studied perovskites for spintronics applications. The atomic composition, microstructure, crystallography, magnetization, thermal, and dielectric properties of a pyrochlore Sm₂Fe₂O₇ system synthesized using sol-gel methods are currently being investigated. Precursor powders were dissolved in citric acid monohydrate to obtain a solution. The obtained solution was stirred and heated using a magnetic stirrer to obtain the gel phase. Then, the gel was dried at 200°C to remove water and organic compounds and form an orange powder. The X-ray diffraction analysis confirms that the structure crystallized as a pyrochlore structure with a tetragonal F4mm (107) symmetry. The presence of Fe³⁺/Fe⁴⁺ mixed states is also revealed by XPS analysis.

Keywords: nanostructures, multiferroic materials, pyrochlores, spintronics

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Authors: Muhammad Habib, Xuefan Zhou, Lin Tang, Guoliang Xue, Fazli Akram, Dou Zhang

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Defect engineering approach is a well-established approach for the customization of functional properties of perovskite ceramics. In modern technology, the high multiferroic properties for elevated temperature applications are greatly demanding. In this work, the Bi-nonstoichiometric lead-free 0.67Biy-xSmxFeO3-0.33BaTiO3 ceramics (Sm-doped BF-BT for Bi-excess; y = 1.03 and Bi-deficient; y = 0.975 with x = 0.00, 0.04 and 0.08) were design for the high-temperature multiferroic property. Enhanced piezoelectric (d33  250 pC/N and d33* 350 pm/V) and magnetic properties (Mr  0.25 emu/g) with a high Curie temperature (TC  465 ℃) were obtained in the Bi-deficient pure BF-BT ceramics. With Sm-doping (x = 0.04), the TC decrease to 350 ℃ a significant improvement occurred in the d33* to 504 pm/V and 450 pm/V for Bi-excess and Bi-deficient compositions, respectively. The structural origin of the enhanced piezoelectric strain performance is related to the soft ferroelectric effect by Sm-doping and reversible phase transition from the short-range relaxor ferroelectric state to the long-range order under the applied electric field. However, a slight change occurs in the Mr 0.28 emu/g value with Sm-doping for Bi-deficient ceramics, whereas the Bi-excess ceramics shows completely paramagnetic behavior. Hence, the origin of high magnetic properties in the Bi-deficient BF-BT ceramics is mainly attributed to the proposed double exchange mechanism. We believe that this strategy will provide a new perspective for the development of lead-free multiferroic ceramics for high-temperature applications.

Keywords: BiFeO3-BaTiO3, lead-free piezoceramics, magnetic properties, defect engineering

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Authors: Monalisa Halder, Amit K. Das, Ajit K. Meikap

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Polymer nanocomposites are very significant materials both in academia and industry for diverse potential applicability in electronics. Polymer plays the role of matrix element which has low density, flexibility, good mechanical strength and electrical properties. Use of nanosized multiferroic filler in the polymer matrix is suitable to achieve nanocomposites with enhanced magneto-dielectric effect and good mechanical properties both at the same time. Multiferroic terbium manganate (TbMnO₃) nanoparticles have been synthesized by sol-gel method using chloride precursors. Terbium manganate-polyvinyl alcohol (TbMnO₃-PVA) nanocomposite film has been prepared by solution casting method. Crystallite size of TbMnO₃ nanoparticle has been calculated to be ~ 40 nm from XRD analysis. Morphological study of the samples has been done by scanning electron microscopy and a well dispersion of the nanoparticles in the PVA matrix has been found. Thermogravimetric analysis (TGA) exhibits enhancement of thermal stability of the nanocomposite film with the inclusion of TbMnO₃ nanofiller in PVA matrix. The electrical transport properties of the nanocomposite film sample have been studied in the frequency range 20Hz - 2MHz at and above room temperature. The frequency dependent variation of ac conductivity follows universal dielectric response (UDR) obeying Jhonscher’s sublinear power law. Correlated barrier hopping (CBH) mechanism is the dominant charge transport mechanism with maximum barrier height 19 meV above room temperature. The variation of dielectric constant of the sample with frequency has been studied at different temperatures. Real part of dielectric constant at 1 KHz frequency at room temperature of the sample is found to be ~ 8 which is higher than that of the pure PVA film sample (~ 6). Dielectric constant decreases with the increase in frequency. Relaxation peaks have been observed in the variation of imaginary part of electric modulus with frequency. The relaxation peaks shift towards higher frequency as temperature increases probably due to the existence of interfacial polarization in the sample in presence of applied electric field. The current-voltage (I-V) characteristics of the nanocomposite film have been studied under ±40 V applied at different temperatures. I-V characteristic exhibits temperature dependent rectifying nature indicating the formation of Schottky barrier diode (SBD) with barrier height 23 meV. In conclusion, using multiferroic TbMnO₃ nanofiller in PVA matrix, enhanced thermal stability and electrical properties can be achieved.

Keywords: correlated barrier hopping, nanocomposite, schottky diode, TbMnO₃, TGA

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Authors: H. Nematifar, D. Sanavi Khoshnoud, S. Feyz

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Bi0.82La0.2Fe1-xCrxO3 (BLFCxO, x = 0.0, 0.02, 0.05 and 0.08) nanoparticles were successfully synthesized by a sol-gel method. The X-ray diffraction (XRD) patterns indicate that the lattice parameters decrease for x ≤ 0.05, firstly, and then they increase for x > 0.05. A transformation from rhombohedral structure to orthorhombic structure occurs at x = 0.08. The transmission electron microscopy (TEM) analysis shows that the average nanoparticle size is about 60-70 nm. The remnant magnetisation (Mr) increases gradually with x to 0.02, then decreases with further increasing x up to 0.05, and finally enchases abruptly in x = 0.08. The coercivity (HC) increases gradually with x to 0.05, and then significantly reduced with increasing Cr substitution. The magnetic ordering temperature (TN) decreases with Cr doping concentration. The M-H curves of all samples exhibit a wasp-waist hysteresis loop in low magnetic region. This property can play an important role for the applications of some multiferroic nano-device.

Keywords: BiFeO3, sol-gel preparation, nanoparticles, magnetic materials, thermal analysis

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Authors: Nidhi Adhlakha, K. L. Yadav

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Three phase magnetoelectric (ME) composites (1-x)(0.7BiFeO3-0.3CoFe2O4)-xPbTiO3 (or equivalently written as (1-x)(0.7BFO-0.3CFO)-xPT) with x variations 0, 0.30, 0.35, 0.40, 0.45 and 1.0 were synthesized using hybrid processing route. The effects of PT addition on structural, multiferroic and optical properties have been subsequently investigated. A detailed Rietveld refinement analysis of X-ray diffraction patterns has been performed, which confirms the presence of structural phases of individual constituents in the composites. Field emission scanning electron microscopy (FESEM) images are taken for microstructural analysis and grain size determination. Transmission electron microscopy (TEM) analysis of 0.3CFO-0.7BFO reveals the average particle size to be lying in the window of 8-10 nm. The temperature dependent dielectric constant at various frequencies (1 kHz, 10 kHz, 50 kHz, 100 kHz and 500 kHz) has been studied and the dielectric study reveals that the increase of dielectric constant and decrease of average dielectric loss of composites with incorporation of PT content. The room temperature ferromagnetic behavior of composites is confirmed through the observation of Magnetization vs. Magnetic field (M-H) hysteresis loops. The variation of magnetization with temperature indicates the presence of spin glass behavior in composites. Magnetoelectric coupling is evidenced in the composites through the observation of the dependence of the dielectric constant on the magnetic field, and magnetodielectric response of 2.05 % is observed for 45 mol% addition of PT content. The fractional change of magnetic field induced dielectric constant can also be expressed as ∆ε_r~γM^2 and the value of γ is found to be ~1.08×10-2 (emu/g)-2 for composite with x=0.40. Fourier transformed infrared (FTIR) spectroscopy of samples is carried out to analyze various bonds formation in the composites.

Keywords: composite, X-ray diffraction, dielectric properties, optical properties

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Authors: A. K. Paul, Vinod Kumar

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Lead free magnetoelectric (ME) nanoparticulate (1−x) BNT-BKT-BMgT−x CFO (x = 0, 0.1, 0.2, 0.3) composite films were synthesized using chemical solution deposition method. The X-ray diffraction and transmission electron microscope (TEM) reveal that CFO nanoparticles were well distributed in the matrix of BNT-BKT-BMgT. The nanocomposite films exhibit both good magnetic and ferroelectric properties at room temperature (R-T). It is concluded that the modulation in compositions of piezomagnetic/piezoelectric components plays a fundamental role in the magnetoelectric coupling in these nanoparticulate composite films. These ME composites provide a great opportunity as potential lead-free systems for ME devices.

Keywords: lead free multiferroic, nanocomposite, ferroelectric, ferromagnetic and magneto-electric properties

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Authors: Sari Aouatef, Larabi Amina

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First-principles calculations within density functional theory based are used to investigate the influence of doped rare earth elements on some properties of perovskite systems Dy₀.₀₆₂₅Y₀.₉₃₇₅FeO₃ and Dy₀.₁₂₅ Y₀.₈₇₅ FeO₃. The electronic and magnetic properties are studied by means of the full-potential linearized augmented plane wave method with Vasp code. The calculated densities of states presented in this work identify the semiconducting behavior for Dy₀.₁₂₅ Y₀.₈₇₅ FeO₃, and the semi-metallic behavior for Dy₀.₀₆₂₅Y₀.₉₃₇₅ FeO₃. Besides, to investigate magnetic properties of several compounds, four magnetic configurations are considered (ferromagnetic (FM), antiferromagnetic type A (A-AFM), antiferromagnetic type C (C-AFM) and antiferromagnetic type G (G-AFM). By doping the Dy element, the system shows different changes in the magnetic order and electronic structure. It is found that Dy₀.₀₆₂₅Y₀.₉₃₇₅ FeO₃ exhibits the strongest magnetic change corresponding to the transition to the ferromagnetic order with the largest magnetic moment of 4.997.

Keywords: DFT, Perovskites, multiferroic, magnetic properties

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Authors: A. V. Trukhanov, S. V. Trukhanov, L. V. Panina, V. G. Kostishin, V. A. Turchenko

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It has been shown that BaFe₁₂O₁₉ is a perspective room-temperature multiferroic material. A large spontaneous polarization was observed for the BaFe₁₂O₁₉ ceramics revealing a clear ferroelectric hysteresis loop. The maximum polarization was estimated to be approximately 11.8 μC/cm². The FeO₆ octahedron in its perovskite-like hexagonal unit cell and the shift of Fe³⁺ off the center of octahedron are suggested to be the origin of the polarization in BaFe₁₂O₁₉. The magnetic field induced electric polarization has been also observed in the doped BaFe_12-x-δSc_xM_δO₁₉ (δ=0.05) at 10 K and in the BaSc_xFe_12−xO₁₉ and SrSc_xFe_12−xO₁₉ (x = 1.3–1.7) M-type hexaferrites. The investigated BaFe_12-xD_xO₁₉ (x=0.1, D-Al³⁺, In³⁺) samples have been obtained by two-step “topotactic” reactions. The powder neutron investigations of the samples were performed by neutron time of flight method at High Resolution Fourier Diffractometer.

Keywords: substituted hexaferrites, ferrimagnetics, ferroelectrics, neutron powder diffraction, crystal and magnetic structures

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Authors: Nassima Sotehi

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This article presents experimental and numerical results concerning the thermal properties of the porous materials used as heat insulator in the buildings sector. Initially, the thermal conductivity of three types of studied walls (classic concrete, concrete with cork aggregate and polystyrene concrete) was measured in experiments by the method of the boxes. Then a numerical modeling of the heat and mass transfers which occur within porous materials was applied to these walls. This work shows the influence of the presence of water in building materials on their thermophysical properties, as well as influence of the nature of materials and dosage of fibers introduced within these materials on the thermal and mass transfers.

Keywords: modeling, porous media, thermal materials, thermal properties

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Authors: T. Vijayashree, A. Gopal

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The aim of the work is to classify and authenticate medicinal plant materials and herbs widely used for Indian herbal medicinal preparation. The quality and authenticity of these raw materials are to be ensured for the preparation of herbal medicines. These raw materials are to be carefully screened, analyzed and documented due to mistaken of look-alike materials which do not have medicinal characteristics.

Keywords: authenticity, standardization, principal component analysis, imaging processing, signal processing

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Authors: Chen-Fu Wang, Lin-Ya Kung

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For traditional painting materials, the artisan used to combine the pigments with different binders to create colors. As time goes by, the materials used for painting evolved from natural to chemical materials. The vast variety of ingredients used in chemical materials has complicated restoration work; it makes conservation work more difficult. Conservation work also becomes harder when the materials cannot be easily identified; therefore, it is essential that we take a more scientific approach to assist in conservation work. Paintings materials are high molecular weight polymer, and their analysis is very complicated as well other contamination such as smoke and dirt can also interfere with the analysis of the material. The current methods of composition analysis of painting materials include Fourier transform infrared spectroscopy (FT-IR), mass spectrometer, Raman spectroscopy, X-ray diffraction spectroscopy (XRD), each of which has its own limitation. In this study, FT-IR was used to analyze the components of the paint coating. We have taken the most commonly seen materials as samples and deteriorated it. The aged information was then used for the database to exam the temple painting materials. By observing the FT-IR changes over time, we can tell all of the painting materials will be deteriorated by the UV light, but only the speed of its degradation had some difference. From the deterioration experiment, the acrylic resin resists better than the others. After collecting the painting materials aging information on FT-IR, we performed some test on the paintings on the temples. It was found that most of the artisan used tune-oil for painting materials, and some other paintings used chemical materials. This method is now working successfully on identifying the painting materials. However, the method is destructive and high cost. In the future, we will work on the how to know the painting materials more efficiently.

Keywords: temple painting, painting material, conservation, FT-IR

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Authors: J. Kosikova, B. Vacenovska, M. Vyhnankova

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The paper reports on the subject of recycling and further use of secondary raw materials obtained from solar panels, which is becoming a very up to date topic in recent years. Recycling these panels is very difficult and complex, and the use of resulting secondary raw materials is still not fully resolved. Within the research carried out at the Brno University of Technology, new polymer materials used for industrial floors are being developed. Secondary raw materials are incorporated into these polymers as fillers. One of the tested filler materials was glass obtained from solar panels. The following text describes procedures and results of the tests that were performed on these materials, confirming the possibility of the use of solar panel glass in industrial polymer flooring systems.

Keywords: fillers, industrial floors, recycling, secondary raw material, solar panel

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Authors: J. Zach, J. Hroudova, J. Brozovsky

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Thermal insulation materials based on natural fibers represent a very promising area of materials based on natural easy renewable row sources. These materials may be in terms of the properties of most competing synthetic insulations, but show somewhat higher moisture sensitivity and thermal insulation properties are strongly influenced by the density and orientation of fibers. The paper described the problem of hygrothermal behavior of thermal insulation materials based on natural plant and animal fibers. This is especially the dependence of the thermal properties of these materials on the type of fiber, bulk density, temperature, moisture and the fiber orientation.

Keywords: thermal insulating materials, hemp fibers, sheep wool fibers, thermal conductivity, moisture

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Authors: Ratna Elizabeth

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Motivation is a very important factor since it contributes a lot to the students’ success in learning a language. Using authentic materials is believed as a mean of increasing the motivation. The materials define as authentic if they are not specifically written for the purpose of language teaching. They are genuine spoken or written language data which are drawn from many different sources. The intention of this study is to investigate the impact of using of authentic materials on students’ motivation. A single case study is conducted to the grade 9 students who learn Indonesian Language as a Foreign Language (ILFL) at an international school in Jakarta, Indonesia. Questionnaires are also distributed to the students to know their perceptions on the using of authentic materials. The results show that the using of authentic materials has increased the students’ motivation in learning the language.

Keywords: authentic materials, ILFL, language learning, motivation

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Authors: Jiao Li

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Language teachers have been expected to play diversified new roles in times of educational changes. Considering the critical role that materials play in teaching and learning, language teachers have been increasingly involved in developing materials. Using identity as an analytic lens, this study aims to explore language teachers’ experiences as materials developers in China, focusing on the challenges they face and responses to them. It will adopt a multimethod approach. At the first stage, about 12 language teachers who have developed or are developing materials will be interviewed to have a broad view of their experiences. At the second stage, three language teachers who are developing materials will be studied by collecting interview data, policy documents, and data obtained from online observation of their group meetings so as to gain a deeper understanding of their experiences in materials development. It is expected that this study would have implications for teacher development, materials development, and curriculum development as well.

Keywords: educational changes, teacher development, teacher identity, teacher learning, materials development

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Authors: Oghenerukome Akponovo, Lynda I. Onyebuchukwu

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Construction waste, along with that of many other industries, contributes significantly to the world's annual solid waste totals. Most of these materials, such as ash from rice hulls, slags, cement kiln dust, tire ash, plastic waste (PW), and silica fumes, end up in landfills or waterways. Some of them might even end up polluting the air from high in the atmosphere. It's sustainable, cheap, and environmentally friendly to recycle these items into new building supplies. When constructing a "Green" structure, the materials employed have the potential to either exacerbate environmental imbalance or maintain a stable ecosystem. The purpose of this research is to take stock of what is already known about recycling's potential in the construction industry and to identify its deficiencies. Therefore, this study systematically reviews the wide range of recycled materials that go into building construction. Recognizing that the construction industry's use of recycled materials has an influence on the environment and that investigating these materials may have a substantial economic impact if they were discovered

Keywords: building, construction, recycled materials, waste management

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Authors: Yiwen Jin, Jing Xiao, Pinfang Su

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The idea of adapting authentic materials in language teaching is from the communicative method in the 1970s. Different from the language in language textbooks, authentic materials is not deliberately written, it is from the native speaker’s real life and contains real information, which can meet social needs. It could improve learners ' interest, create authentic context and improve learners ' communicative competence. Authentic materials play an important role in CFL（Chinese as a foreign language） classroom. Different types of authentic materials can be used in different ways during learning and teaching. Because of the COVID-19 pandemic，a lot of Chinese learners are learning Chinese without the real language environment. Although there are some well-written textbooks, there is a certain distance between textbook language materials and daily life. Learners cannot automatically fill this gap. That is why it is necessary to apply authentic materials as a supplement to the language textbook to create the real context. Chinese teachers around the world are working together, trying to integrate the resources and apply authentic materials through different approach. They apply authentic materials in the form of new textbooks, manuals, apps and short videos they collect and create to help Chinese learning and teaching. A review of previous research on authentic materials and the Chinese teachers’ attempt to adapt it in the classroom are offered in this manuscript.

Keywords: authentic materials, Chinese as a second language, developmental use of digital resources, materials development for language teaching

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Authors: Mikołaj Szyca

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Friction elements of rail vehicle brakes are more and more often made of composite materials that displace cast iron. Materials are tested primarily in terms of their dynamic abilities, but the material structure of brake pads and linings changes during operation. In connection with the above, the changes taking place in the tested rubbing materials were analyzed using X-ray computed tomography in order to obtain data on changes in the structure of the material immediately after production and after a certain number of operating cycles. The implementation of microtomography research for experimental work on new friction materials may result in increasing the potential for the production of new composites by eliminating unfavorable material factors and, consequently, improving the dynamic parameters.

Keywords: composite materials, friction pair, X-ray computed microtomography, railway

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Authors: Abdulla Almulla, Wafaa Mahdi

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Building materials can make a significant contribution to the level of natural radioactivity in closed dwelling areas. Therefore, developing an expert system for monitoring the activity concentrations (ACs) of naturally occurring radioactive materials (NORMs) existing in building materials is useful for limiting the population’s exposure to gamma radiation emitted from those materials. The present work not only is aimed at examining the indoor radon concentration emitted by the building materials that are originated from various countries but are commercially available in Kuwait, but also is aimed at developing an expert system for monitoring the radiation emitted from these materials and classifying it as normal (acceptable) or dangerous (unacceptable). This system makes it possible to always monitor any radiological risks to human health. When detecting high doses of radiation, the system gives warning messages.

Keywords: building materials, NORMs, HNBRA, radionuclides, activity concentrations, expert systems

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Authors: Michael T. Ajayi, Oluwakemi E. Fapojuwo

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Farmers are in need of regular and relevant information relating to new technologies. Production of extension materials has been found to be useful in facilitating the process. Extension materials help to provide information to reach large numbers of farmers quickly and economically. However, as good as extension materials are, previous materials produced are not used by farmers. The reasons for this include lack of involvement of farmers in the production of the extension materials, most of the extension materials are not relevant to the farmers’ environments, the agricultural extension agents lack capacity to prepare the materials, and many extension agents lack commitment. These problems led to this innovative capacity building of extension agents. This innovative approach involves five stages. The first stage is the diagnostic survey of farmers’ environment to collect useful information. The second stage is the development and production of draft extension materials. The third stage is the field testing and evaluation of draft materials by the same farmers that were involved at the diagnostic stage. The fourth stage is the revision of the draft extension materials by incorporating suggestions from farmers. The fifth stage is the action plans. This process improves the capacity of agricultural extension agents in the preparation of extension materials and also promotes engagement of farmers and beneficiaries in the process. The process also makes farmers assume some level of ownership of the exercise and the extension materials.

Keywords: capacity building, extension agents, dissemination, information/technologies

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Authors: Isik Cetintav, Cenk Misirli, Yilmaz Can, Damla Gunel

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This work investigates experimental and numerical analysis of open die forging of multimetallic materials. Multimetallic material production has recently become an interesting research field. The mechanical properties of the materials to be used for the formation of multimetallic materials and the mechanical properties of the multimetallic materials produced will be compared and the material flows of the use of different lubricants will be examined. Furthermore, in this work, the mechanical properties of multimetallic metallic materials produced using different materials will be examined by using different lubricants. The advantages and disadvantages of different lubricants will be approached with the bi-metallic material to be produced. Cylindrical specimens consisting of two different materials were used in the experiments. Specimens were prepared as aluminum sleeve and copper core and upset at different reduction. This metal combination present a material model of which chemical composition is different. ABAQUS software was used for the simulations. Simulation and experimental results have also shown reasonable agreement.

Keywords: multimetallic, forging, experimental, numerical

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Authors: Sarka Keprdova, Nikol Zizkova

Abstract:

This paper focuses on the presentation of results which were obtained as a part of the project FR-TI 3/742: “System of Lightweight Materials for Finishing of Buildings with Waste Raw Materials”. Attention was paid to the lightweighting of polymer-modified mortars applicable as adhesives, screeds and repair mortars. In terms of repair mortars, they were ones intended for the sanitation of aerated concrete.

Keywords: additives, light aggregates, lightweight materials, lightweight mortars, polymer-modified mortars

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Authors: Josef Brychta, Jiri Kratochvil, Marek Pagac

Abstract:

The group of progressive cutting materials can include non-traditional, emerging and less-used materials that can be an efficient use of cutting their lead to a quantum leap in the field of machining. This is essentially a “superhard” materials (STM) based on polycrystalline diamond (PCD) and polycrystalline cubic boron nitride (PCBN) cutting performance ceramics and development is constantly "perfecting" fine coated cemented carbides. The latter cutting materials are broken down by two parameters, toughness and hardness. A variation of alloying elements is always possible to improve only one of each parameter. Reducing the size of the core on the other hand doing achieves "contradictory" properties, namely to increase both hardness and toughness.

Keywords: grained cutting materials difficult to machine materials, optimum utilization, mechanic, manufacturing

Procedia PDF Downloads 266

Authors: Punya Tepsing

Abstract:

This research aimed to study the beliefs in auspicious materials of entrepreneurs in Muang Hat Yai. The data were collected via documentary research and field work including interviews, observations shops in Hat Yai which used auspicious materials to bring lucks to the shops. The results were as follows. The beliefs in auspicious materials that the entrepreneurs had were of three areas: 1) The auspicious materials could correct the improperness of the shop location, for example, the shop situated opposite a branch road, a shrine, or a bank. The owner usually corrected it by putting Chinese auspicious materials in front of or in the shop, for example, a lion holding a sword in his mouth, or a mirror, etc. 2) The auspicious materials could bring in more income. The owner of the shop usually put the auspicious materials such as a cat beckoning and a bamboo fish trap believed to trap money in front of or inside the shop. 3) The auspicious materials like turtles, paired fish and a monster holding the moon in his mouth could solve life problems including health, family, and safety problems. The use of these auspicious materials showed the blending of the beliefs of the Chinese shop entrepreneurs with the Thai folk beliefs. What is interesting is that Hat Yai is located near the three southern border provinces which are the unrest area and this may cause the number of tourists to decline. This prompted them to build a mechanism in adjusting themselves both to save their lives and to increase the number of customers. Auspicious materials can make them feel more confident.

Keywords: belief, auspicious materials, shop, entrepreneur, Maung Hat Yai

Procedia PDF Downloads 211

Authors: Vesna Pungercar, Florian Musso

Abstract:

Identifying materials that can substitute rare or expensive natural resources is one of the key challenges for improving resource efficiency in the building sector. With a growing world population and rising living standards, more and more salt is produced as waste through seawater desalination and potash mining processes. Unfortunately, most of the salt is directly disposed of into nature, where it causes environmental pollution. On the other hand, salt is affordable, is used therapeutically in various respiratory treatments, and can store humidity and heat. It was, therefore, necessary to determine salt materials already in use in building construction and their hygrothermal properties. This research aims to identify salt materials from different scientific branches and historically, to investigate their properties and prioritize the most promising salt materials for indoor applications in a thermal envelope. This was realized through literature review and classification of salt materials into three groups (raw salt materials, composite salt materials, and processed salt materials). The outcome of this research shows that salt has already been used as a building material for centuries and has a potential for future applications due to its hygrothermal properties in a thermal envelope.

Keywords: salt, building material, hygrothermal properties, environment

Procedia PDF Downloads 135