bluuebunny/crossref_metadata_2025 huggingface dataset:
Simulation of Heat Transfer to Turbulent Nanofluid Flow in an Annular Passage
Authors: Oon C.S. , Badarudin A. , Kazi S.N. , Fadhli M.
Published: April 2014

The heat transfer in annular heat exchanger with titanium oxide of 1.0 volume % concentration as the medium of heat exchanger is considered in this study. The heat transfer simulation of the flow is performed by using Computational Fluid Dynamics package, Ansys Fluent. The heat transfer coefficients of water to titanium oxide nanofluid flowing in a horizontal counter-flow heat exchanger under turbulent flow conditions are investigated. The results show that the convective heat transfer coefficient of the nanofluid is slightly higher than that of the base fluid by several percents. The heat transfer coefficient increases with the increase of the mass flow rate of hot water and also the nanofluid.
Numerical Simulation of Water Flow Velocity for Microfluidic Application Using COMSOL Multiphysics
Authors: Salih Nurulazirah Md , Hashim Uda , Nayan Nafarizal , Soon Chin Fhong , Sahdan Mohd Zainizan
Published: April 2014

In microfluidic devices, the most important aspect has to be considered for the manufacturing process is the geometric design. Simulation is a good approach for determining the performance of the design. In this study, several microchannel designs were simulated using COMSOL Multiphysics 4.2 software in order to find the optimized geometry. It involves a study of different shape, diameter, length, and angle of microchannels design, and its influence on the water flow velocity. From the simulation results, an optimize microchannels design was obtained which consists of 100 μm cross-sectional diameter, 4:3:11 channel length ratio, and 35 degrees of microchannels angle. Further study could be done to improve the finding of the microfluidic simulation design for better water flow behavior.
Dual-Power PV-Grid Energy System – An Alternative to the Off-Grid PV Energy System
Authors: Ibrahim Intan Rahayu , Omar Ahmad Maliki , Hussain Zakaria , Mohd Hussain Mohd Najib , Mohammad Noor Siti Zaliha
Published: April 2014

The Dual-power PV-grid energy system was initiated to reduce the capital installation cost of PV energy system and to make use the lower tariff rate offered at off-peak period. In this paper, the system configuration, architecture and operation of the system are described and discussed. The prototype has been developed and runs 24-hours to supply the load. Meteorological and electrical data collected prove the successful of such system. The system is expected to reduce 89% of electricity bill with estimated cost of energy (COE) of USD1.15/kWh. It is suggested that the dual-power PV-grid system is beneficial to serve as an alternative implementation of the off-grid PV energy system.
Catalytic Pretreatments of Palm Tree Biomass for the Extraction of Lignin, Cellulose and Hemicelluloses
Authors: Ali Md Eaqub , Ahamad Mohammad Nasir Uddin , Hamid Sharifah Bee Abd
Published: April 2014

Lignocellulosic biomass consists of three polymeric components, namely cellulose, hemicellulose and lignin. Lignin is an amorphous polymer made by three different phenolic compounds, namely guaiacyl alcohol (G), syringyl alcohol (S) and p-coumaryl alcohol (H). It is the main component of cell walls and is composed of a 3D randomized net linked to cellulose and hemicelluloses. It functions as a biological barrier and glue to retain linked hemicelluloses and celluloses. Lignin and lignin derived compounds have important applications in paper and pulp industry as well as barrier thin film industry. On the other hand, cellulose and hemicelluloses are important feed stocks for biofuel, specialty chemicals and bio-surfactants. Degradation of lignin is a key step for the production of biofuel from biomass resources. Lignin can be depolymerized with enzyme and metal based catalyst, and acid peroxidases. Enzymatic approaches are green but expensive and slow. Acid peroxidases are often harsh, non-specific, and environmentally unfriendly and destroys lignin, cellulose and hemicelluloses. Several types of metal catalysts have been proposed for the selective cleavage of lignin. For example, nanoNi (O) was prepared by reducing of NiCl2 with NaBH4 under ultrasonication, Fe3O4 (NiAlO)x was prepared by calcination of Mg (Ni)-Al hydrotalcite with incorporation of Fe3O4 followed by reduction with hydrogen, and NiO nanosheets were synthesized by reduction of Ni (NO3)2 with urea using benzyl alcohol as a structure directing agent. These metal based catalysts demonstrated promising results by depolymerizing lignin under thermal ultrasonic conditions. This paper reviewed various catalysts, their synthesis processes and mechanistic actions for the pretreatment of palm tree biomass for the extraction of all three components, namely cellulose, hemicelluloses and lignin.
Factors Influencing the Involvement of the Community in Recycling Programme in Perlis, Malaysia
Authors: Ab Jalil Mohd Faizal , Kamarudzaman Ain Nihla , Mohd Noor Nor Fashihah , Ismail Mohd Fadli
Published: April 2014

A recycling programme study was conducted in residential areas in Kangar, Perlis. This study was conducted to identify the main factors that influence community participation in recycling programme. It is also expected to help the local authorities in dealing with solid waste disposal problems. A total of 80 respondents was given the questions and the sampling was done using a convenience sampling method. Results from data analysis found that knowledge on recycling is one of the factors affects the activity of the recycling program. Knowledge through environmental education can help increase recycling activities where it focuses on the importance of recycling in details. Therefore, those who do recycling activities are influenced by information from the learning efforts of formal and informal education.
Iron Doped TiO2 Photocatalysts for Environmental Applications: Fundamentals and Progress
Authors: Riaz Nadia , Mohamad Azmi Bustam-Khalil , Mohd Shariff Azmi
Published: April 2014

One of the most pervasive problems affecting people throughout the world is inadequate access to clean water and sanitation. Problems with water are expected to grow worse in the coming decades, with water scarcity occurring globally. Many recent studies have been reported on the photodegradation of the organic compounds in industrial wastewater in the presence of TiO2 semiconductor as photocatalyst. Heterogeneous photocatalysts using iron as a dopant metal, so far, have been reported for various environmental applications. This paper highlights the recent advances and applications of Fe-TiO2 photocatalysis for the degradation/photodegradation of various pollutants, alkanolamines and other organic pollutants like phenols and dyes.
Silica Supported Mesoporous Titania: A Green Catalyst for Removing Environmental Pollutants and Generating Green Energy
Authors: Hamid Sharifah Bee Abd , Hossain S.M. Azad , Ali Md Eaqub
Published: April 2014

Titania (TiO2) is one of the most unique catalysts, crucially important in photo-green chemistry. The mesoporous TiO2 has large surface area, uniform pore size and open frameworks for the transfer of mass and charges. TiO2 has photocatalytic activity which can degrade both organic and inorganic compounds. The band gap energy of TiO2 can be modified by doping various metal oxides to make it tunable for application in solar cells. Various catalytic metals such as Au, Pt and Pd can be synthesized on TiO2 surface to enlarge its application in various catalytic molecular transformations. Thus TiO2 has promising application in the production of the renewable energy, degradation of environmentally hazardous components, generation of solar cells and sensors. A large number of efforts have been made to synthesize mesoporous TiO2 materials with high surface area and uniform pore size. However, they were not cost effective for applications in environment and green energy generation. The photocatalytic actions of TiO2 can further kill or transform harmful microorganisms into harmless or less harmful ones. This paper reviewed synthesis methodology of silica supported mesoporous TiO2 and their applications in environmental photocatalysis and solar cells.
Effect of High Temperature during Electroless Nickel Process
Authors: Sauli Zaliman , Retnasamy Vithyacharan , Hashim Uda , Vairavan Rajendaran , Yeow Aaron Koay Terr , Palianysamy Moganraj , Ayub Ramzan Mat
Published: April 2014

This paper presents the correlation between electroless process time, immersion gold process time and the bump height in electroless nickel immersion gold (ENIG). A certain bump height need to be achieved in order to create acceptable solder bumps for reflow process. The study was done using a full factorial design of experiment (DOE). The DOE matrix is made of two levels with two factors. Analysis was done by plotting the main effects plot for each factor. The results suggest that higher process time increases the plating rate where the temperature fixed at 100 °C. It can be concluded that electroless nickel time has more influence to the bump height compared to immersion gold time.
Surface Roughness Influence on O2 and Ar RIE Gas Treated Aluminum Surface
Authors: Sauli Zaliman , Retnasamy Vithyacharan , Hashim Uda , Taniselass Steven , Palianysamy Moganraj , Ayub Ramzan Mat
Published: April 2014

This study reports on the preliminary investigations on the effect of Reactive Ion Etch (RIE) parameters on the surface characteristics of Al bond pad. Investigation is done employing Design of Experiment (DOE) method. Quantity of Oxygen, Argon, ICP power and BIAS power were varied to get 16 sets of recipes. This provides 16 samples with different combination of RIE parameters. Surface characteristics of the samples were analyzed using Atomic Force Microscopy (AFM).Data collected were in terms of Surface Roughness (RA), Peak Vs Valley (P-V) and Surface Root-Mean-Square Roughness (RMS). Result shows that combination of these RIE parameters does not vastly affect the surface characteristics of the Al bond pad.
Utilization of Rice Husk Ash and Waste Sludge from Cutting Glass Manufacturing with Angthong Pottery
Authors: Kaewtabut Yutthana , Sirimongkol Wansika , Thueploy Adisak , Nilpairach Siriphan
Published: April 2014

Efficiently utilization of rice husk ash (RHA) and waste sludge from cutting glass manufacturer (WSG) as additives to pottery clay would yield positive economic impacts, such as more friendly industrial ecosystems. In this study, The RHA and WSH were used as additives to Angthong pottery clay (APC) and casting and fired properties were examined. Two sets of sample with a mixture consisting of 60% APC, 20% RHA, and 20% WSG (CRG formula) and non-added clay (C100 formula) were prepared by slip casting technique. Samples were fired at temperature 900 °C and 1100°C; then the viscosity of slurry, linear shrinkage, water adsorption, and 3-point bending strength were measured. The results showed that the optimum viscosity for slip casting of CRG and C100 were 1638 cP and 983 cP, respectively. The water adsorptions of all samples decrease while their shrinkage and strength increase with temperature. At 900°C, the water adsorption and the strength of CRG were 32% and 1184 psi, respectively. Comparatively, CRG’s water absorption was 1.5 times higher than C100’s, while their mechanical strength was insignificantly different. This due to the RHA behaves as pore forming and the WSG promotes the sintering of samples.
Preparation and Characterization of Fly Ash and Aluminium Waste Geopolymer
Authors: Onutai Sujitra , Jiemsirilers Sirithan , Wada Shigetaka , Thavorniti Parjaree
Published: April 2014

Geopolymeris an alumino-silicate material with three dimensional amorphous structures. The main compositions are silica and alumina which were decomposed by alkaline solution. Geopolymer materials not only have comparable or superior properties to portland cement, but also have lower greenhouse emission. In this study, Preparation and characterization of geopolymer were investigated. The main composition of fly ash from Mae Moh power plant is SiO2 and Al2O3. The major composition of Aluminium waste from aluminium frame industry is Al2O3.The geopolymer pastes were mixed at various proportions of FA:Al-waste of 100:0 80:20 60:40 and 40:60 by weight. Sodium hydroxide and sodium silicate were used as alkali activators.A mass ratio of 2.5 Na2SiO3/NaOH and three concentrations of NaOH (5 10 15 M) were used. Geopolymer were cured at ambient temperature for 7days. Properties of geopolymer specimens were measured for example compressive strength, bending strength, phase by XRD, and bonding by FT-IR.
Photocatalytic Performance of ZnO Nanoparticles Synthesized by Microwave-Assisted Process Using Zinc-Dust Waste as a Starting Material
Authors: Sujaridworakun Pornapa , Natrchalayuth Kornkamol
Published: April 2014

This study aimed to use the zinc dust which is a waste from hot-dip galvanizing plant for the synthesis of ZnO nanoparticles using microwave-assisted process. The precursor solution was prepared by dissolved as received zinc-dust powder in nitric acid. Then it was precipitated by NaOH at required pH and microwave irradiated in a household microwave oven at power of 100W for 10-20 min. The effects of preparation conditions and an addition amount of poly ethylene glycol (PEG; MW2000) for synthesis of ZnO on its properties were investigated. The synthesized nanoparticles were characterized for their phase structure, morphology and surface area by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and Brunauer-Emmett-Teller (BET), respectively. The photocatalytic activity was determined by the degradation of methylene blue solution under UV irradiation. It was found that microwave heat treatment and addition of optimum amount of PEG could enhance the photocatalytic activity of precipitated ZnO particles. The resultant ZnO particles prepared by an addition of 0.25wt% PEG and microwave irradiation for 20 min exhibited the highest photodegradation rate among other products.
Effects of Manganese Addition on Phase Formation Behavior and Dielectric Properties of ((K0.5Na0.5)0.935Li0.065)NbO3 Ceramics
Authors: Wongsaenmai Supattra , Maensiri Santi , Yimnirun Rattikorn
Published: April 2014

In this study, ceramics in ((K0.5Na0.5)0.935Li0.065)NbO3+ xMnO2(mol%) ceramics (when x = 0.0025, 0.0050, 0.01 and 0.015) were successfully prepared by the conventional mixed-oxide technique. The structural phase formation and microstructure were characterized by x-ray diffraction technique (XRD) and scanning electron microscopy (SEM). The crystal structure was identified by XRD as a single-phase perovskite structure, with tetragonal symmetry. The microstructure shows different grain size with different composition x. This study clearly showed that the Mn has influence on the dielectric properties in ((K0.5Na0.5)0.935Li0.065)NbO3ceramics.
Strength Improvement of Porous Ceramics by the Surface Infiltration of Strengthening Materials
Authors: Kim Geun Hee , Pee Jae Hwan , Kim Jin Ho , Cho Woo Seok , Kim Hyung Tae , Kim Kyung Ja
Published: April 2014

One method of improving the strength of porous ceramics is to add Al2O3 in ceramic raw materials and then they must be sintered at high temperature for densification. However, the non-plastic property of Al2O3 leads to a decline in plasticity of clay body, thus severely interfering with forming process. Besides porous ceramics have fine cracks and pores distributed within porous ceramics, these fine cracks on the surface also result in weakening of the sintered body. In this study, we attempted to improve the strength while compensating for the weakness of porous ceramics by the surface infiltration of strengthening materials after the first sintering step at 900°C. MgCl2, Al (NO3)3, and KNO3 were used as surface strengthening materials. The effect of Infiltration factors, solution concentrations (1-3 moles) and infiltration time (1-5 seconds) on the mechanical properties of the sintered body are investigated. When the strength was assessed after the second sintering step at 1250°C, an 30% increase in strength was obtained with Al (NO3)3 infiltrated in a 3 mole solution for 5 seconds. An analysis of the crystal phase of the strengthened body revealed a higher intensity of the mullite phase arising from the infusion of surface strengthening materials. Consequently, the mullite phase led to a higher strength value.
Preparation of Calcium Phosphate Cement Utilizing Dicalcium Phosphate Dihydrate and Calcium Carbonate
Authors: Kosachan Nudthakarn , Jaroenworaluck Angkhana , Jiemsirilers Sirithan , Jinawath Supatra , Stevens Ron
Published: April 2014

Calcium phosphate cement has been widely used as a bone substitute because of its chemical similarity to natural bone. In this study, calcium phosphate cement was prepared using dicalcium phosphate dihydrate (CaHPO4.2H2O) and calcium carbonate (CaCO3) as starting raw materials. The cement pastes were mixed and the chemistry adjusted with two different aqueous solutions of sodium hydroxide (NaOH) and disodium hydrogen phosphate (Na2HPO4). Concentrations of the solution were varied in the range 0.5 to 5.0 mol/L with the ratio of solid/liquid = 2 g/ml. The cement paste was then poured into a silicone mold having a diameter of 10 mm and a height 15 mm. Setting times for the cement were measured using a Vicat apparatus. XRD, FT-IR, and SEM techniques were used to characterize properties and microstructure of the cement. From the experimental results, it is clear that different concentrations of Na2HPO4 and NaOH have affected the setting times of the cement. The relationship between concentration of NaOH and Na2HPO4 and setting time, including final properties of the cement, is discussed.
The Effect of the Si/Al Ratio on the Properties of Water Treatment Residue (WTR)-Based Geopolymers
Authors: Waijarean Naprarath , Asavapisit Suwimol , Sombatsompop Kwannate , MacKenzie Kenneth J.D.
Published: April 2014

This research aimed to develop a cementing material from synthetic geopolymers using water treatment residue (WTR) from a water treatment plant in Bangkaen as an aluminosilicate starting material, with the addition of rice husk ash (BHA) from a paddy factory in Thailand as a source of crystalline silica, to achieve Si/Al ratios of 2.00, 3.00, 4.00 and 5.00. The geopolymers were prepared by NaOH activation of the five compositions of WTR and BHA mixtures, followed by curing at ambient temperature (29±2°C). The compressive strengths of the geopolymers were determined after 3, 7, 28 and 60 days. The samples cured for 28 days were examined by XRD, FTIR and SEM. The Si/ Alratio of 2.00 was found to produce the greatest strength at all curing times. After 7 days, all samples were 30% stronger than the 3 day-samples. XRD revealed the presence of sodium aluminium silicate hydrate, while an FTIR vibration band related to the geopolymer product shifted to 1000 cm-1. SEM revealed a homogeneous non-crytalline and dense microstructure in the sample with the highest Si/Al ratio of 5.00, suggesting that a transformation to sodium silicate had occurred in this sample.
Investigation of Melting Behavior of Low-Enthalpy Glass Batches
Authors: Tapasa Kanit , Meechoowas Ekarat , Naknikham Usuma , Jitwatcharakomol Tepiwan
Published: April 2014

Batch modification with low-enthalpy raw materials is the effective approach for reducing the glass melting energy. In the previous study, it was found that introducing wollastonite (CaSiO3) as a source of CaO instead of calcium carbonate (CaCO3) in the soda-lime glass batch can fasten the melting process. It is because the modified batch with CaSiO3 has lower chemical heat demand, ΔHochem, which is equivalent to the standard heat of batch-to-melt conversion. In order to investigate the kinetic property of the modified batch, the melting behaviour of 2 kg modified batch was studied. The results showed that the temperature of the modified batch increased at a faster rate than the original batch. The properties of the glass from the modified are also similar to the original batch.
Using the Polka Dot Technique of Color Slip for Ceramic Decorative
Authors: Ruammaitree Kanokkanya
Published: April 2014

The inspiration of the work was polka dot. It was a regulation of nature can be seen in shape and structure of living and non-living things. The ceramic products were decorated by used slip color before being left to dry at room temperature. The ceramic products were fired at 1230 °C in oxidation atmosphere. The ceramic products were appearance of slip dots that was slightly raised above surface gave ceramics are wonderful and interesting texture.
Development of Carbon Emission Label for Local Ceramic Product
Authors: Kandananond Karin
Published: April 2014

Although the manufacturing businesses have played an important role in generating the highest GDP for Thailand, they also emit more greenhouse gas (GHG) than other sectors. Due to the cap and trade scheme by European Union (EU), the carbon footprint is the GHG emitted by products, organization or persons and it has to be tracked and recorded. Since the ceramic production process also has a major contribution on the emission, its carbon footprint is a piece of product information which cannot be ignored. In this research, the carbon footprint for the whole life cycle of a local ceramic product was recorded and calculated. It is interesting to note that the resource extraction stage has contributed to the highest emission followed by the product use, manufacturing, disposal and distribution. The results from this research are useful for local ceramic manufacturers who want to export their products to the EU countries and it is also important for the customers who are concerned about the environment.
Preparation of Nanocomposite Particles from Typha angustifolia and Egg Shells
Authors: Eiad-Ua Apiluck , Insuang Koonyad , Changsuwan Supattra , Viriya-Empikul Nawin
Published: April 2014

Nanocomposite Paticles have been successfully synthesized from Typha Angustifolia and Egg Shells via 3 steps synthesis; hydrothermal, pyrolysis and/or ball milling techniques, respectively. Typha Angustifolia was subjected to produce fine carbon particles by two stage processes of hydrothermal (at 200 °C for 4 h) and carbonization technique (under Argon atmosphere at 700 °C for 2 h) while the egg shells were convert to white powder (calcium oxide) by calcining under air atmosphere at 900 °C for 4 h. The samples have been characterized by scanning electron microscopy (SEM) and fourier transform infrared spectroscopy (FTIR) to investigate the morphology and surface function, respectively. The experimental results revealed that the planetary mill have effect on the composites between carbon and calcium. Calcium was deposited on the surface of carbon material. Moreover, when the calcium was increased leading to higher performance of milling (i.e. the smaller composite product was observed).
Hyperfine Interactions on Magnetic Ions Nuclei in Titanates
Authors: Agzamova Polina A. , Leskova Yulia V. , Nikiforov Anatoliy E.
Published: April 2014

The electric and magnetic hyperfine interaction parameters (υQ, η, Hc) on 47,49Ti nuclei in lanthanum and yttrium titanates were calculated in the cluster model by the unrestricted Hartree-Fock method. The calculation in the cluster approach describes the experimental data better than that in the frameworks of LDA and LDA+U model and modern crystal-field theory.
Magnetic Response of Pr1-xLaCexCuO4 in Comparison with Hole-Doped Cuprates
Authors: Sherman Alexei
Published: April 2014

The magnetic susceptibility of the optimally doped Pr1-xLaCexCuO4in the superconducting state is calculated using thet-Jmodel of Cu-O planes, the Mori projection operator technique, and the dispersion of electron bands derived from photoemission experiments. The electron band folding across the antiferromagnetic Brillouin zone border, which is inherent in the crystal, leads to a commensurate low-frequency response. The same band folding causes the appearance of a supplementary spin-excitation branch, which coexists with usual spin excitations. This coexistence can explain two maxima observed in the frequency dependence of the susceptibility. The two nested spin-excitation branches lead to a comb of closely spaced peaks in momentum cuts, which presumably are not resolved in experiment, being seen as a broad commensurate peak up to 100 meV. Reasons for differences in magnetic responses of electron- and hole-doped cuprates are discussed.
Phase Transitions in Magnets with Competing Exchange Interactions
Authors: Belokon Valery I. , Dyachenko Olga I.
Published: April 2014

In this investigations the systems of the nanoparticles with competing exchange interactions are considered. The critical concentrations and possible types of magnetic states of particles in the case of direct exchange and RKKY interaction in the framework of the random interaction field method are determined. It is observed that in magnetic materials with the competition of the direct and indirect exchanges changing the type of ordering is possible at the change in the intensity of the indirect exchange under the influence of external factors.
Magnetic and Structural Properties of Nanocomposite ZnO-Fe3O4 Films Prepared by Solid-State Synthesis
Authors: Bykova Liudmila E. , Myagkov V.G. , Tambasov I.A. , Bayukov O.A. , Zhigalov Victor S. , Mikhlin Y.L. , Nemtsev I.V. , Bondarenko G.N.
Published: April 2014

A simple method for obtaining ZnO-Fe3O4 nanocomposites using solid-state reaction Zn + 3Fe2O3 ZnO + 2Fe3O4 is suggested. An analysis of the characteristics and properties of ZnO-Fe3O4 nanocomposites was carried out by a combination of structural and physical methods (X-ray diffraction, scanning electron microscopy, photoelectron spectroscopy, Mössbauer measurements, X-ray fluorescent analysis, and magnetic measurements). The magnetization of the hybrid ZnO-Fe3O4 films is equal to 440 emu/cm3. The resulting Fe3O4 nanoparticles are surrounded by a ZnO shell and have sizes ranging between 20 and 40 nm.
Magnetorefractive Effect in Doped La1-xKxMnO3 Thin Films
Authors: Gan’shina Elena A. , Sukhorukov Yurii P. , Telegin Andrey V. , Bessonov Vladimir D. , Kaul Andrey R.
Published: April 2014

Influence the deposition of La3+ ions by monovalent K+ ions on magnetorefractive effect on magnetoreflaction and magnetotransmission modes in the infrared range for La1-xKxMnO3 epitaxial thin-films (х=0.05, 0.10, 0.15 и 0.18) has been studied. It has been shown that the magnetorefractive effect, transversal Kerr effect and magnetoresistance reach the maximum in optimally doped films at highest Curie temperature. The good agreement between calculated in framework of magnetorefractive effect theory and experimental data takes place only for optimally doped films, with potassium concentrations of 15 % and 18 %. At the other doping levels the films become charge and magnetic inhomogeneous. Magnetic and charge homogeneity influence strongly on magnetooptical effects in films. The resonance-like lines in magnetoreflection spectra of films are connected with the shifting of reflection minimum before the phonon bands under a magnetic field has been observed.
Ensembles of γ-Fe2O3 Nanoparticles Formed during Devitrification of Borate Glasses
Authors: Ivanova Oxana S. , Edelman Irina S. , Ivantsov Ruslan D. , Petrakovskaya Eleanora Anatolievna , Velikanov Dmitrij A. , Trofimova Natalia N. , Zubavichus Yan V.
Published: April 2014

Structural, magnetic and magneto-optical properties of borate glasses co-doped with Fe and the lager radius ions are presented. Maghemite, γ-Fe2O3, nanoparticles arise in the glasses as a result of their thermal treatment in different regimes. Magnetization FC and ZFC temperature dependences demonstrate the superparamagnetic behavior of the particles with the blocking temperature below the room temperature. The EMR spectra measurements revealed a significant anisotropy with a large contribution of the nanoparticles’ surface anisotropy. The FR maximum centered near 700 nm is a characteristic feature of the investigated glasses.
Influence of Fe-Co Ratio and Ni,Cr Dopants on Structural Evolution of Metallic Amorphous Alloys
Authors: Kotvitckii Aleksandr , Kraynova Galina , Frolov Anatoly , Ivanov Vitaly , Plotnikov Vladimir
Published: April 2014

In this paper the analysis of structure changes in series of amorphous alloys with different Fe/Ni and Fe/Co ratio and Cr addition is made. It has been shown that within temperature range 230С <T< 4500С the structure of alloys keeps its amorphous character and only a slight changes in heat flow occur. At temperatures above 450°C the structure evolution depends of the Fe/Ni and Fe/Co ratio and some dopants.
Nanocrystalline Soft Magnetic Fe-, Co-Based Alloys Doped by Hf, Mo and Zr with Enhanced Thermal Stability of Magnetic Properties
Authors: Potapov Anatolii P. , Dmitrieva Natalia V. , Lukshina Vera A. , Volkova Elena G. , Filippov Boris N.
Published: April 2014

Magnetic properties, thermal stability and structure of the alloys - (Fe0.6Co0.4)86Hf7B6Cu1 (1), (Fe0.7Co0.3)88Hf7B4Cu1 (2) and (Fe0.7Co0.3)88Hf4Mo2Zr1B4Cu1 (3) obtained in the form of ribbons quenched from the melt were investigated after their nanocrystallization in the course of the thermal (TA) and stress (SA) annealings in the air at different temperatures. In all three alloys SA resulted in the induction of magnetic anisotropy with an easy axis along the direction of the ribbon. It is established that the alloy 3 after SA at 620°C for 20 min has the best thermal stability of magnetic properties, which remained practically unchanged after the subsequent annealing at 550°C for 26 hours. Magnetic properties of the alloys 1 and 2 subjected to SA under the same conditions did not change after annealing at 500°C.
Influence of Magnetostatic Interactions on Magnetization Process of Iron-Containing Coatings, Produced Using the Plasma Electrolytic Oxidation Method
Authors: Kharitonskii Peter V. , Frolov Anatoly , Boev Sergey A. , Rudnev Vladimir S. , Tkachenko I.A. , Morozova V.P. , Lukiyanchuk I.V. , Adigamova M.V. , Ustinov A.Y.
Published: April 2014

In this paper we research the process of magnetization of iron-containing coatings obtained on aluminum and titanium plasma electrolytic oxidation. It is shown that the formation of a remnant magnetic moment mainly determined by the magnetostatic interaction particles (phases). This interaction leads to a decrease of the blocking volume of particles (phases). Thus, a large number of superparamagnetic particles (phases) obtain stable magnetic moments and are involved in creating of the remnant magnetization of the sample.
Investigation of the Co Films Growth on Si (111) Surface with Copper Silicide Nanostructures
Authors: Ermakov Konstantin , Ognev Alexey V. , Samardak Alexander , Kozlov Alexey , Ovsaynnikov Artur , Mikoluk Evgeniy , Chebotkevich Ludmila A. , Saranin Alexander , Romashev Lazar , Solin Nicolay , Ustinov Vladimir
Published: April 2014

In this study the features of the growth processes of copper silicide nanostructures on Si (111) were investigated. The nanostructures were grown by molecular beam epitaxy. It has been shown that the islands and nanowires are formed at the substrate temperature 550°C. The nanostructures have ideal facets and lateral edges. The long side of nanowires is oriented along the crystallographic direction <110> Si. We have shown that there is a range of thicknesses at which nanowires generally grow.
Scaling in the Quantum Hall Regime for a Double Quantum Well Nanostructure in High Magnetic Field
Authors: Arapov Yurii G. , Gudina Svetlana V. , Klepikova Anna S. , Neverov Vladimir N. , Novokshonov Sergey G. , Okulov Vsevolod I. , Charikova Tatiana B. , Harus German I. , Shelushinina Nina G. , Yakunin Mikhail V.
Published: April 2014

The longitudinal ρxx(B) and Hall ρxy(B) magnetoresistances are investigated in the integer quantum Hall effect regime in n-InGaAs/GaAs double quantum well nanostructures in the magnetic fields B up to 16 T at temperatures T = (0.05-4.2) K before and after IR illumination. The analysis of the quantum Hall effect plateau-plateau transitions based on the scaling hypothesis with regard to electron-electron interaction was carried out.
The Second-Order Spin-Reorientation Phase Transition in Thin Magnetic Film
Authors: Siryuk Julia A. , Bezus Alexey V.
Published: April 2014

The mechanism of spin-reorientation phase transmission (SRPT) has been examined. The structure change of domain boundaries in process of phase transmission (PT) has been researched. The models of domain structure (DS) relevant to experiment have been offered. It is shown that in connection with temperature change of the anisotropy constants the structure of domain boundaries and view of DS changes as well, SPRT and PT takes place in the domain boundaries.
Effect of Substrate RF-Bias on Exchange Coupling in Fe20Ni80/Fe50Mn50 Films
Authors: Gor'kovenko Alexander N. , Lepalovskij V.N. , Vas’kovskiy V.O. , Savin Peter A. , Shchegoleva Nina N.
Published: April 2014

The effect of physical and technological factors on the effectiveness of the exchange coupling in two-layer film structures such as Fe20Ni80/Fe50Mn50 has been investigated. The dependences of the coercive force and the exchange bias field of permalloy layer on presence of a buffer Ta layer and its thickness, the order of sputtering and the thickness of Fe20Ni80 and Fe50Mn50 layers, substrate temperature and the features of radio-frequency (RF) substrate bias during deposition were investigated. It has been found that the substrate RF bias improves homogeneity of microstructure and reduces the surface roughness of permalloy layer. This in turn increases the magnetic pinning of permalloy layer and creates the prerequisites for the practical application of layered structures with higher thickness of the ferromagnetic layers.
Magnetic Properties of Co Thin Films Evaporated under Normal and Oblique Incidence
Authors: Kharmouche Ahmed
Published: April 2014

We have evaporated series of Co thin films under vacuum onto silicon and glass substrates at a perpendicular and oblique incidence. The thickness of the magnetic layer ranges from 20 to 400 nm. The static magnetic properties have been performed by means of magnetic force microscopy (M.F.M.) and Alternating Gradient Field Magnetometer (A.G.F.M.) techniques. The influence of the magnetic layer thickness and the deposition angle are studied. As results, it is found a decrease of the coercive field from 250 Oe, for t = 20 nm, to 95 Oe, for t = 400 nm. TheseHcvalues for obliquely evaporated cobalt films are larger than those measured for cobalt films evaporated at normal incidence, found to be equal to a few Oe. It is also found a decrease of the anisotropy field, from 1.6 kOe for the 20 nm Co thick film to 0.95 kOe for the 200 nm Co thick film. Furthermore, an increase of these fields with the increase of the deposition angle is found, as well. The easy axis of the saturation magnetization lies in the film plane, irrespective of the substrate nature. These results, and others, are presented and discussed.
Magnetic Behavior of Single Ni Nanowires and its Arrays Embedded in Highly Ordered Nanoporous Alumina Templates
Authors: Samardak Alexander S. , Ognev Alexey V. , Sukovatitsina Ekaterina V. , Stebliy Maxim E. , Modin Evgeny B. , Chebotkevich Liudmila A. , Mahmoodi R. , Hosseini M.G. , Peighambari S.M. , Nasirpouri Farzad
Published: April 2014

We report on magnetization reversal and geometry dependent magnetic anisotropy of Ni nanowire arrays electrodeposited in nanoporous alumina templates. Using micromagnetic simulation we have found that magnetization reversal mechanism in arrays with different nanowire diameters is curling. This magnetic behavior appears with propagation of the domain wall along a nanowire. The calculations have been proven by the analysis of hysteresis curves. To explain magnetic properties of closely-spaced nanowire arrays we have taken into consideration the magnetostatic interaction between adjacent nanowires and their structural defects, like as boundary grains. The investigated magnetic domain pattern of individual bended nanowires confirms rather complicated magnetization reversal mechanism than either coherent rotation of magnetization or its curling. Competition between the shape and magnetoelastic anisotropies can induce an unusual zigzag-like domain pattern in a single nanowire.
Phase Transitions in the Antiferromagnetic Heisenberg Model on a Triangular Lattice with the Next-Nearest Neighbor Interactions
Authors: Murtazaev Akai K. , Ramazanov Magomedsheykh K.
Published: April 2014

The critical behavior and phase transitions (PT) of the three-dimensional antiferromagnetic Heisenberg model on a layered triangular lattice with nearest-neighbor (J) and next-to-nearest neighbor (J1) interactions is studied by the replica Monte Carlo method. The first order phase transition has been revealed in the studied model based on the histogram method of processing data of the Monte Carlo for systems with large linear dimensions. Shown that the system exhibits the pseudouniversal critical behavior in the case of small lattices.
Spin Injection Mechanisms for Radiation and Detection of Terahertz Waves Based on Magnetic Nano Junction
Authors: Vilkov Evgeniy Alexandrovich , Chigarev Sergey G. , Zilberman Petr E.
Published: April 2014

Spin injection mechanisms for radiation and detection of terahertz waves based on magnetic nano junction are considered. High efficiency of terahertz radiation is theoretically explained and the method of the detection of this radiation is offered. The device of the spin injected terahertz radiators is presented.
The Influence of Magnetic Inhomogeneous State on Thermopower and Magnetothermopower in Sm0.55Sr0.45MnO3 Manganites
Authors: Koroleva Liudmila I. , Morozov Artiom S. , Zhakina Elina S.
Published: April 2014

Thermopower α and magnetothermopower α/α were studied in the single-crystal Sm0.55Sr0.45MnO3 samples, containing clusters of three types: ferromagnetic clusters with the Curie temperature TC = 134 K, A-type antiferromagnetic clusters with the Neel temperature TNATC and CE-type antiferromagnetic clusters with the TNCE = 240 K. The curves of temperature dependence of α (T) and {α/α}(T) have extrema in the TNCE-region: large maximum on the first and sharp minimum on the second. Negative magnetothermopower in minimum achieves the giant value 50% in magnetic field 13,2 kOe. It is shown that thermopower is essentially caused by the presence of CE-type antiferromagnetic clusters, in which exists charge order, displacing oxygen ions
Magnetoimpedance of Amorphous Ribbons with Polymer Covering
Authors: Moiseev Alexey A. , Petrov Anton V. , Derevyanko Mikael S. , Lukshina Vera A. , Potapov Anatoly P. , Bukreev Dmitry A. , Semirov Alexandr V. , Safronov Alexandr P. , Kurlyandskaya Galina V.
Published: April 2014

Magnetic properties and magnetoimpedance were studied for as-cast Fe5Co75Si4B16 rapidly quenched amorphous ribbons and Fe5Co75Si4B16/polymer amorphous ribbon based composites with the following polymer coverings: modified rubber solution in o-xylene, copolymer solution of butyl methacrylate and methacrylic acid in isopropanol and solution of polymethylphenyl resin in toluene. All selected composites showed very good adhesion of the coverings and allowed us to provide long term temperature measurements, including measurements under stress. Polymer coverings have an effect on the temperature sensitivity of the impedance value. The present study demonstrates the promising future for the development of magnetically active conductor/polymer composites for creating new sensors. Modification of the composition and thickness of the polymer coverings can be the basis for creation of the detectors with a unique set of functional properties. Polymer covering can perform the protective and reinforcing role that is particularly important in the case of nanocrystalline alloys and the polymer covering can also affect and improve the functional properties of the magnetic core.
Interfacial Electronic Scattering in Fe/Cr Superlattices
Authors: Lobov Ivan D. , Kirillova Margarita M. , Romashev Lazar N. , Milyaev Mikhail A. , Ustinov Vladimir V.
Published: April 2014

The magnetorefractive effect (MRE) has been measured in the infrared spectral region of 1.2-28 μm in MBE-grown Fe/Cr superlattices with variable Fe and Cr layers thicknesses inp-polarized light. The magnetic and magnetooptical properties have been studied as well. From the MRE spectra modeling in the framework of magnetoreflection theory for multilayered structures, the parameters of interfacial spin dependent scattering of conductivity electrons have been defined for different types of exchange coupling between adjacent Fe layers. The dependence of interfacial scattering parameters on Fe and Cr layer thickness is discussed.
Magnetoimpedance of Amorphous Ferromagnetic CoFeSiB Ribbons in the Wide Temperature Range
Authors: Semirov Alexander V. , Derevyanko Michael S. , Bukreev Dmitriy A. , Moiseev Alexey A. , Kurlyandskaya Galina V.
Published: April 2014

The influence of the temperature, elastic tensile stresses and external magnetic field on the impedance of amorphous Co75Fe5Si4B16 ribbons was studied. It was observed that the character of the elastic tensile stresses influences the impedance and its changes in the external magnetic field are determined by a temperature of the ribbons. It was shown that changes of the stressimpedance character and magnetoimpedance temperature dependences were caused by a change in the sign of a magnetostriction constant with the temperature.
Magnetoelectric Polarization of Paramagnetic HoAl3-XGaX(BO3)4 Single Crystals
Authors: Gudim Irina A. , Eremin Evgeny V. , Molokeev Maksim S. , Temerov Vladislav L. , Volkov Nikita V.
Published: April 2014

HoAl3-xGax(BO3)4 (0 ≤ х ≤ 3) single crystals were grown from Bi2Mo3O12Li2MoO4-based fluxes. Structural inversion twinning depending on crystal composition and heat treatment conditions is revealed. It is established that upon substitution of Ga3+ ions for Al3+ the magnetic characteristics of the crystals do not significantly change, while the magnetoelectric polarization decreases with increasing gallium content. The measured value and sign of polarization charges depend on a ratio between the left and right isomers.
Magnetic and Dielectric Properties of PbFeBO4 and PbMnBO4 Single Crystals
Authors: Pankrats A.I. , Sablina K.A. , Velikanov D.A. , Bayukov O.A. , Vorotynov A.M. , Balaev A.D. , Molokeev M.S. , Kolkov M.I.
Published: April 2014

PbFeBO4 and PbMnBO4 single crystals were synthesized. The X-ray, magnetic, dielectric, Mössbauer, and resonance investigations of the crystals were fulfilled. It is established that single-crystal PbFeBO4 is an antiferromagnet with a Néel temperature TN =114 K, while PbMnBO4 is a ferromagnet with a Curie temperature TC = 31 K. Both single-crystal compounds have a strong anisotropy of the magnetic and dielectric properties.
Magnetoelectric Properties of NdxBi1-xFeO3 Thin Films
Authors: Aplesnin Sergei S. , Kretinin Vasilii V. , Ostapenko Aleksey A. , Galyas Anatoley I. , Yanushkevich Kazimir L.
Published: April 2014

Multiferroics based on BiFeO3with spatially-modulated antiferromagnetic structure are investigated. The goal of this work is to define possibility of orientation phase transitions in magnetic and electric system by replacing Bi with 4f Nd ion depending on temperature in external magnetic field. On NdxBi1-xFeO3films the measurements of permittivity, loss tangent at frequences 100 Hz < ω < 105Hz and at temperatures 300 К < T < 1000 K without magnetic field and in magnetic field with H=0.8 Т were made. A drop in temperature dependence of permittivity in magnetic field was found. Magnetoelectric properties can be explained in model of changing of magnetic structure in magnetic field as a result of interaction of electric and magnetic subsystems.
Spin-Wave Spectrum in the Sinusoidal Superlattice with Amplitude and Phase Inhomogeneities
Authors: Ignatchenko Valter A. , Tsikalov Denis S.
Published: April 2014

Effects of both the phase and the amplitude inhomogeneities of different dimensionalities on the Greens function and on the one-dimensional density of states of spin waves in the sinusoidal superlattice have been studied. Processes of multiple scattering of waves from inhomogeneities have been taken into account in the self-consistent approximation.
Nonlinear Magnetostatic Wave Propagation through One Dimensional Finite Magnonic Crystals
Authors: Sheshukova Svetlana E. , Beginin Evgenii N. , Morozova Maria A. , Sharaevskii Yurii P. , Nikitov Sergey A.
Published: April 2014

A model describing the propagation of surface magnetostatic waves in the one-dimensional finite length magnonic crystal (MC) with losses was constructed. The features of microwave pulse passing through the band gap of MC were investigated experimentally. The conditions of soliton-like pulse formation were defined experimentally and by numerical simulation.
The Domain Structure and Magnetic Hysteretic Properties of Mn55.5Al44C0.5 Alloy in Different Structural States
Authors: Korznikova Galia F.
Published: April 2014

Lorentz electron microscopy was used to compare the domain structure in Mn55.5А145.5 C0.5 ferromagnetic alloy in different structural states. The samples with different structural states were processed by means of deformation and thermal treatment at different conditions. It was established, that grain refinement causes the changes in domain structure configuration and affects the magnetization mechanism.
Experimental Study and Numerical Modelling of Magnetic Domain Walls Drift in Ferrite Garnet Crystals
Authors: Pamyatnykh Lidia A. , Shmatov Georgy A. , Lysov Mikhail S. , Pamyatnykh Sergey E. , Mehonoshin Dmitry S.
Published: April 2014

The results of study of domain walls oscillations in harmonic magnetic field H = H0sin (2πft) oriented perpendicular to ferrite garnet (TbErGd)3(FeAl)5O12 (111) sample plate for amplitudes that include the drift of domain walls are reported. Numerical modelling of domain walls motion was performed for frequencies f~102 Hz, where the drift is observed experimentally. Comparison of results of numerical modelling with experimental results shows their qualitative agreement. It was established that domain walls oscillations amplitude is a linear function of amplitude of oscillating magnetic field.
The Improved Magneto-Optical Kerr Effect Method of Magnetic Anisotropy Measurements in Thin Films and Nanostructures
Authors: Stebliy Maxim E. , Ognev Alexey V. , Samardak Alexander , Tregubov Gleb , Mikoluk Evgeniy , Chebotkevich Ludmila A.
Published: April 2014

Magnetic anisotropy of thin films and nanodisk arrays made of cobalt has been studied by the magneto-optical anisometry with modulated field. The improved method of magnetic anisotropy field measurements in thin films has been proposed. This method has been used for cobalt nanodisk arrays in order to investigate anisotropy of magnetization reversal processes due to dipole-dipole interaction between nanodisks.
The Expeimental Setup for Measuring of Thermal Parameters of Magnetic Fluids in AC Magnetic Field
Authors: Elkhova Tatiana M. , Gun'ko Yurii K. , Pyatakov Alexander P. , Spichkin Yurii I. , Dawson Kenneth , Tishin Alexander M.
Published: April 2014

Magnetic nanoparticle heating in alternating magnetic field is the novel approach to the hyperthermia technique for cancer treatment. The accurate measuring of the specific heat absorption rate of the magnetic fluid is the critical issue in the search for efficient materials to minimize the concentration of the magnetic nanoparticles in human tissues. In this work the heat absorption measurement setup consisting of a system of the magnetic field generation, a temperature measuring system, a cooling system, and an external computer control system has been developed. The results of the calibration as well as the results of measurements on the cobalt ferrite nanoparticles are presented.