bluuebunny/crossref_metadata_2025 huggingface dataset:
Photodynamic Combined with Magnetic Field Applications for Viability Activation of Anaerobic Photosynthetic Bacteria
Authors: Astuti Suryani Dyah , Nike Dwi G.D. , Supriyanto Agus , Triyana Kuwat
Published: July 2015

This paper reports the influence of light exposure (photodynamic) and magnetic field application on viability activation of anaerobic photosynthetic bacteria (rhodobacter sphaeroides). For photosynthetic process, the rhodobacter sphaeroides have bacteriochlorophyll and carotenoid as major and accessory pigments, respectively. A customized equipment was developed for investigating the effect of light and magnetic field applications on the growth of the bacterial colonies. It was consisted of three main parts, namely a sample holder, an array of light emitting diode (LED) as light source and Helmholtz coils as magnetic field source. The systems of this equipment were controlled by a microntroller of AVR ATMega-8535. Prior to the application in vitro, all LEDs were calibrated, both their intensity and wavelength. After the treatments, all bacteria substances were grown in photosynthetic media (PMS) for 48 hours followed by calculating the number bacterial colonies growth using a total plate count (TPC) method and Quebec colony counter. It was found that the growths of bacterial colonies were influenced by both light intensity and wavelength of LED array. At the same intensities, the wavelength of 430 nm showed highest effect on the growth of bacterial colonies. In addition, upon application of the optimum light combined with magnetic field, the highest growth of bacterial colonies was achieved more than 110% when the optimized light source of energy dose was 204 J/cm2 and magnetic field was 1.8 mT.
Designing of a High Voltage Power Supply for Electrospinning Apparatus Using a High Voltage Flyback Transformer (HVFBT)
Authors: Munir Muhammad Miftahul , Hapidin Dian Ahmad , Khairurrijal
Published: July 2015

Research on nanofiber materials is actively done around the world today. Various types of nanofibers have been synthesized using an electrospinning technique. The most important component when synthesizing nanofibers using the electrospinning technique is a DC high voltage power supply. Some requirements must be fulfilled by the high voltage power supply, i.e., it must be adjustable and its output voltage reaches tens of kilovolts. This paper discusses the design and development of a high voltage power supply using a diode-split transformer (DST)-type high voltage flyback transformer (HVFBT). The DST HVFBT was chosen because of its simplicity, compactness, inexpensiveness, and easiness of finding it. A pulse-width modulation (PWM) circuit with controlling frequency and duty cycle was fed to the DST HVFBT. The high voltage power supply was characterized by the frequency and duty cycle dependences of its output voltage. Experimental results showed that the frequency and duty cycle affect the output voltage. The output voltage could be set from 1 to 18 kV by changing the duty cycle. Therefore, the nanofibers could be synthesized by employing the developed high voltage power supply.
Analysis of Wood’s Capacitance Characteristic to its Hardness
Authors: Esofita Mufti , Djamal Mitra , Taruno Warsito P. , Al Huda Mahfudz , Baidillah Marlin , Pari Gustan , Damayanti Ratih
Published: July 2015

A capacitance sensor has been designed to investigate the correlation between wood capacitance value, Janka hardness rating and density. The sensor was developed based on parallel plates using copper as the electrodes. Capacitance values were measured using CV-circuit, 20 Vp-p, 2.5 MHz. Five wood specimens from forest plantation that is Karet (Hevea brasiliensis), Pulai (Alstonia sp.), Pinus (Pinus mercusii), Sengon (Paraserianthes falcataria), and fast growing teak (Tectona grandis) were tested. Each specimen was measured in tangential and radial directions under 0% moisture content conditions. The designed sensor was capable to distinguish the capacitance values in tangential and radial directions. The measurement results showed that wood capacitance value has a good relation with wood’s hardness and density.
Application of Radon Isotopes to Determine Permeable Zones in Rajabasa Geothermal Field, Indonesia
Authors: Haerudin Nandi , Wahyudi  , Risdianto Dikdik , Suryanto Wiwit
Published: July 2015

This study aims to determine permeable zones (i.e. fault or fracture zones) in the Rajabasa geothermal field using radon isotopes. Radon concentration of soil gas was measured by Scintrex Radon detector RDA 200 consisting of 123 measurement station. The measurement site spacing are between 200 m and 350 m. The Radon concentration was classified based on a statistical approach, i.e. low, high and very high. Very high value of Radon concentration, called Radon anomaly, associated with permeable zones. From the Radon anomaly contour map, a 2D Radon migration from the source to the surface was modelled by means of numerical simulation. Finally, the Radon contour map was overlaid with the surface geological map and the resistivity contour map in the area of study. It suggests that the Radon anomaly correlates with the location of permeable zone in the centre part of the study area i.e. mud pool manifestation at the Kunjir and the Cugung (Bulakan) fumarole. Based on numerical simulation, the width of the fault is 2,800 m; velocity of fluid is 0.08 m/s and the Radon concentration is 860,000 Beq/m3. The resistivity contour map results low resistivity value of 0 Wm – 100 Wm indicating the conductive zone coincide with permeable zones based on Radon measurements. Furthermore, the peak of the profile curve of Radon concentration could be an indication of fault systems in this area.
A Simple Spectrometer Using Various LEDs and a Photodiode Sensor for Photocatalytic Performance Evaluation
Authors: Rajak Abdul , Munir Muhammad Miftahul , Abidin Muhammad Sainal , Khairurrijal
Published: July 2015

The degradation of pollutants in a waste water with the aid of light as an energy source enabler is one of the photocatalysis processes. Because a textile dye dissolved in water is often used to model the waste water, the degradation of color becomes a major variable to indicate the water clarity after the photocatalysis process occured. Therefore, a sensitive instrument to measure the degradation of color is required. This paper reports a simple spectrometer using a photodiode sensor OPT101 and a light emitting diode (LED). The light emitted by the LED passes through the waste water so that its intensity is reduced. Then, the photodiode sensor receives the light with reduced intensity. In order to test the spectrometer performance, a waste water model was prepared by employing a textile dye in water with various concentrations. Curves showing the relationships between concentration and voltage output of the sensor were obtained for different colors of LEDs (white, blue, orange, red and yellow). A microcontroller is used to process the voltage output of the sensor and an LCD then displays the concentration. The results shows that red LEDs has a smallest error with an error of less than 5%.
Boundary Data Analysis of Continuous Wave Domain Diffuse Optical Tomography with Structured Refined Mesh Algorithm for Product Quality Control
Authors: Nadhira Vebi , Kurniadi Deddy , Juliastuti Endang , Yudha T. A. , Budiono Kurniadi
Published: July 2015

Diffuse optical tomography is promising technology for non destructive evaluation on product quality control. In order to improve the forward sensitivity, structured refine mesh method was applied on continuous wave domain diffuse optical tomography imaging. This study was conducted on numerical and phantom object. These objects were illuminated by the near infrared source from object’s boundary. To obtain the boundary parameter data, a set of near infrared detector were placed on the periphery of the object. To validate our proposed forward analysis method, boundary parameter data of simulation are shown in comparison with that of experiment. In this study, we vary the position and the value of optical coefficient of defect on the object then we analyze the forward problem sensitivity. The result of this study indicated that continuous wave domain-diffuse optical tomography is promising for product quality control.
Metrological Overview for Coordinate Measuring Machines
Authors: Dhoska Klodian , Kübarsepp Toomas , Dorri Altin , Pramono Agus
Published: July 2015

In manufacturing system, 3D Coordinate Measuring Machines (CMM) are widely used for inspection services where the product should be subjected to the verification of design specifications. It is usually necessary to know the accuracy of 3D CMM equipment during the verification process of the product quality in mass production. To insure and increase the accuracy of 3D CMM the international series standards ISO 10360 are used. This paper presents the importance of the establishment of traceability to international standards as a key role for the reliability of 3D CMM measurement results.
An X-Ray Detector Using a Fluorescent Material ZnS:Ag Attached on a Phototransistor in Darlington Configuration
Authors: Kusminarto  , Fadela Ramacos
Published: July 2015

X-rays have been widely used in medical imaging system. CT Scan is one of the important diagnostic equipments in medical field that uses X-rays as a probe. In the latest CT-Scan generation an array of X-ray detector in a gantry is employed. Solid state detector and gas filled detector are currently used. These type of detector have relatively large in physical size. This influenses the size of the machine as well as its performance. In order to obtain an X-ray detector in a small size a phototransistor was exploited. The phototransistor was attached on a fluoroscent screen and arranged in Darlington configuration. The phototransistor in Darlington configuration was calibrated using visible light. The results showed that there was a linear correlation between the phototransistor output (mV) and the light intensity impinging on the phototransistor surface. A fluoroscent material (ZnS:Ag) then attached on the phototransistor surface. They work as an X-ray detector and calibrated using an X-ray beam generated from an X-ray machine. The results also confirmed that there was a linear correlation between the detector output (mV) and the X-ray intensity stricking the detector surface. The active area of the detector was explored by scanning the surface of the detector in vertical as well as in horizontal directions. The effective diameter of the active area of the detector was found to be 2.2 mm.
A Gold Bar Purity Testing Method Based on Vibration Characteristics
Authors: Prasetiyo Iwan , Sihar I. , Agusta K. , Handayani Ismi
Published: July 2015

Vibration characteristic of a structure is unique due to mainly its material and geometrical properties. Hence, a variation imposed on either one or both the parameters can cause a different vibration response. This fact can be used to develop an alternative approach in testing the purity of gold particularly when the gold bar (Au) is no longer isotropic material due to the presence of other metals. A fake gold bar is commonly made by filling inside of the bar with other material for example Tungsten or Wolfram (W) which has density nearly the same as gold but its price is cheaper. This can not be identified easily without performing a testing as it has the same appearance as the pure gold bar. The purpose of this research is to develop gold bar purity testing method by observing natural frequencies and Frequency Response Function (FRF) of vibration response. For early development, the vibration response of gold bar and fake one are investigated. For this, numerical calculations are used rather than measurements. The results show that the natural frequencies and frequency response function (FRF) are useful information to detect whether a metal bar is pure gold bar or containing other metals. Higher natural frequency orders are required when the volume of tungsten in the bar reduces as the gap of lower order natural frequencies of pure gold bar and the fake become small. Moreover, the excitation point at corner and central of area of gold bar are suggested to be chosen during purity testing
Design of Dual Edge 0.5 Hz Precision Frequency Counter for QCM Sensor
Authors: Wijayanto Vani R. , Sakti Setyawan P.
Published: July 2015

Frequency counter is used widely in many electronic and sensor applications. In a resonance sensor system such as Quartz Crystal Microbalance or Surface Acoustic Wave, frequency counter is the main part of the measuring system. Precision, stability, accuracy and compactness of the frequency counter become a fundamental aspect of the development. In a sensor system, a frequency counter is needed to have a precision down to 1 Hz or even better with a sampling rate of one second. Increasing a precision of the counter from 1 Hz to 0.5Hz will result an improvement of the sensor output signal resolution. In this work we have designed a circuit system which is implemented in a single chip device to get a counting of the frequency down to 0.5Hz without suffering the sampling time. To implement such a required system, a CPLD is one of the best options to be used as a device for the frequency counter. In this paper a dual edge frequency counter using CPLD XC2C256 has been successfully developed. The system consists of 2 channels, 26 bits dual edge frequency counter. The system can count a frequency up to 67MHz, which is enough for the many QCM sensor system. By using a high stabile TCXO and calibrated again a rubidium oscillator, the developed system results in a high stability and accuracy. A precision of 0.5Hz with sampling rate of 1 second can be achieved by the developed system.
Development of a Wireless Sensor Network for Temperature and Humidity Monitoring
Authors: Munir Muhammad Miftahul , Mataubenu Kostan D.F. , Salam Rahmat Awaludin , Latief Hamzah , Khairurrijal
Published: July 2015

The development of a wireless sensor network system for temperature and humidity monitoring is described. The system is composed of two main parts, namely an end device and a coordinator. The end device consists of an SHT10 sensor, an XBee Pro RF module, an ATMega8535 microcontroller, and a battery. The coordinator consists of an XBee Pro RF module and an SIM900 GSM module. The temperature and humidity data were sent by the end device to the coordinator and they were forwarded to the web server via GPRS communication using the SIM900 GSM module. In order to the data stored in the database can be accessed in real time via the internet, a web server is developed by using CodeIgniter (CI). It was shown that each end device can communicate very well with the coordinator. Moreover, the data are received in accordance with the timing of delivery was given.
Development of Digital Variable Frequency Triangle Signal Generator Using Cygnal C8051F005 SoC
Authors: Widiatmoko Eko , Munir Muhammad Miftahul , Khairurrijal
Published: July 2015

A circuit for generating triangle waveform with variable, digitally controlled frequency has been developed. The circuit utilizes a Cygnal C8051F005 System-on-a-Chip (SoC) for controlling the output frequency. Two 12-bit Digital to Analog Converters (DACs) included in the SoC feeds a voltage to a frequency converter to generate symmetrical bipolar triangle signal using four op-amps, which is an improved version of commonly found voltage controlled oscillator circuit. With one DAC, the frequency can be swept from 7 Hz to 3000 Hz while the amplitude remains constant. The second DAC is used to fine tune the frequency. The circuit also outputs synchronous square wave for frequency measurement by the SoC. The circuit was applied for testing or characterizing electronic devices or samples with fully digital control input from the user.
Development of Electronic Nose with Low-Cost Dynamic Headspace for Classifying Vegetable Oils and Animal Fats
Authors: Triyana Kuwat , Taukhid Subekti M. , Aji Prasetyo , Nur Hidayat Shidiq , Rohman Abdul
Published: July 2015

A portable electronic nose (e-nose) using low-cost dynamic headspace and commercially metal oxide gas sensors has been developed. This paper reports evaluation on the performance of the e-nose to classify vegetable oils (sunflower and grape seed oils) and animal fats (mutton, chicken and pig fats). The e-nose consists of a dynamic headspace sampling, a gas sensor array and a real-time data acquisition system based on ATMega-16 microcontroller. The dynamic headspace can divided into two chambers, i.e. sample and gas sensor array room. It is also equipped with three small fans for adjusting sensing and purging processes. Principal component analysis (PCA) was used for measurement data analysis after all features being extracted. The first two principal components were kept because they accounted for 91.1% of the variance in the data set (first and second principals accounted for 72.9, 18.2% of the variance, respectively). This results show that the e-nose can distinguish vegetable oils and animal fats. This work demonstrates for the future that the e-nose with low-cost dynamic headspace technique may be applied to the identification of oils and fats in halal authentication.
Fluxgate Based Detection of Magnetic Material in Soil Subsurface
Authors: Indrasari Widyaningrum , Djamal Mitra , Srigutomo Wahyu , Handayani Gunawan , Hadziqoh Nur , Ramli
Published: July 2015

Fluxgate sensor has high sensitivity and temperature stability, small size and low power consumption. Fluxgate sensors can often provide very useful alternative in determining the location or position of a magnetic object, where other technologies cannot be used. For example, the GPR only, does not provide maximum results when used to characterize the magnetic material in the conductive subsurface or has a high reflectivity zone, but fluxgate sensors are capable. Characterization of magnetic materials in the soil subsurface is required. It is used as a proxy to determine the content of heavy metals and pollutants in the soil. In this work, we have carried out the development of fluxgate sensors for detection of magnetic material in soil subsurface. The fluxgate element consists of two pick-up coils, four excitation coils, and the ferromagnetic core. The highest sensitivity of fluxgate sensors that have been developed is 877 mV/µT and a maximum absolute error of 0.066 mV/µT. This paper will discuss the influence of the frequency of the primary magnetic field of the solenoid on the sensor response, the influence of soil magnetic susceptibility, and the effect of the presence of magnetic material in the soil subsurface to the sensor response.
Reconfigurable Controller Based on Fuzzy Descriptor Observer for Nonlinear Systems with Sensor Faults
Authors: Indriawati Katherin , Jazidie Achmad , Agustinah Trihastuti
Published: July 2015

In this paper, the FTC system for multiple operating condition nonlinear systems subjected to sensor faults is developed by applying reconfigurable control scheme. The scheme generates any modified control signal using appropriate additive reference signal to the nominal control system. The proposed observer is developed based on descriptor approach in the fuzzy Takagi-Sugeno model configuration in order to accommodate some operating conditions of a nonlinear system. The simulation result shows that the proposed method has capability to compensate more than one sensor fault occurred in a three-tank benchmark system even there is a change in condition operation as well as in reference signal.
Self-Powered Wireless Sensor for Forest-Fire Detection in Sumatera with Various Environmental Energy Source
Authors: Umar Lazuardi , Hamzah Y. , Setiadi R.N.
Published: July 2015

This paper presents a fire sensor module which is powered by harvested energy from the surrounding environment. The complete system consists of a transmitter module that sources energy from a mini generator energized by wind and thermal energy. The presented green energy poweredfire sensor is environmentally friendly and can be mass produced at a very low cost. A prototype of the forest-fire sensor consisted of transmitter and receiver module of STM110 EnOcean Firma has been constructed. The fire-sensor module detects the presence of fire in the vicinity using an NTC (negative temperature coefficient) temperature sensor. The thermistor is mounted on the exterior of the prototype (casing) and its switch-temperature is set between 90°C and 95°C. A rapid rise in the temperature above the set switch-temperature causes a rapid change in the sensor resistance, indicating the presence of a nearby fire. In response, the sensor would send a telegram to the central station (receiver module).
Suitability of Self-Fabricated Solid Tissue Phantom for Quality Assurance Examination of Shortwave Diathermy (SWD) Unit
Authors: Lamidi  , Koentjoro Sekartedjo , Nasution Aulia
Published: July 2015

Diathermy is commonly used treatment method for pain relief in musculoskeletal tissue, rheumatisms, inflammation etc., by which the increased temperature in tissue induces better blood perfusion and quickens the healing process. But improper maintenance and incorrect handling might lead to degrade the output power or may cause serious burns, respectively. So correct regular QA measurements for the output power would be necessary, in order to give the correct and safe treatment plan. A suitable tissue phantom is then needed to accomplish this task. For this purpose, a glycerol-based solid tissue phantom has been self-fabricated with insertion of four precission temperature sensors (LM 35) at locations of of 1.0 cm, 1.5 cm, 2.0 cm, and 2.5 cm from the surface (each of which are 2 cm laterally separated). Prior calibration of these four sensors for temperature range of 20 - 50°C (using a calibrated temperature calibrator) show very good accuracy and precission properties. The phantom is then tested by exposing it with RF waves output of SWD unit with time variation of 2-14 min (step 2 min), and output power variation of 20% - 80% of its maximum power (incremental step of 20%).
Web-Based Surface Level Measuring System Employing Ultrasonic Sensors and GSM/GPRS-Based Communication
Authors: Munir Muhammad Miftahul , Salam Rahmat Awaludin , Widiatmoko Eko , Supriadani Yundi , Rahmadhani Andri , Latief Hamzah , Khairurrijal
Published: July 2015

Water surface level should get special attention as water can cause disasters such as flood when its surface exceeds a certain level. A real time early warning system to monitor water surface level is necessary for avoiding severe effects of flood to human life. A web-based water level measuring system using an ultrasonic sensor can be an alternative choice for developing the early warning system. It is known that the system has advantages in the installation and maintenance compared to other systems. This paper discusses the design of a water level measuring system integrated with an internet web server. Ultrasonic sensors are used to measure the water surface level. A GSM / GPRS-based communication system is applied for sending measured water levels to a web server. The results indicate that the measurement data are in accordance with the water levels manually obtained. The results also show that the system works real time.
Determining a Tracer Diffusivity by way of the Darken-Manning Equation for Interdiffusion in Binary Alloy Systems
Authors: Paul T.R. , Belova I.V. , Levchenko E.V. , Evteev A.V. , Murch G.E.
Published: July 2015

The self-or tracer diffusivity of one component in a binary alloy is often required when there is knowledge of the other component’s self-or tracer diffusivity and the interdiffusivity (and the thermodynamic factor). In the present paper, this problem is addressed for the random alloy model by applying three possible approximations having different levels of accuracy: Darken (low level of accuracy), Manning (medium level of accuracy) and Moleko, Allnatt and Allnatt (MAA) (high level of accuracy). There are unexpectedly large differences between the results of these approximations that sometimes are reflected in the high sensitivity of the vacancy-wind factor to the level of approximation. Generally, for the application of Manning and the MAA approximations, it is found that there is a difference in the number of self-diffusivity roots depending on whether the tracer diffusivity is available for the faster diffuser or for the slower diffuser and depending on how close the composition is to the forbidden (according to Manning’s description) region. Provided that the interdiffusion coefficient (divided by the thermodynamic factor) is greater than the available self-diffusion coefficient multiplied by its complementary composition, the application of the Darken approximation always results in one self-diffusivity root.
Surface Effects and Critical Dimensions of Iron Nanoparticles
Authors: Kozlowski Gregory , Chaudhary V. , Turgut Z. , Kosai H. , Sheets A. , Bixel T. , Wheatley A. , Abdulkin P. , Knappett B. , Jefferson David , Matusiewicz M. , Kasperczyk J. , Makowska-Janusik M.
Published: July 2015

The surface effects on the critical dimensions of ferromagnetic nanoparticles have been studied. Iron nanoparticles with different mean diameter from 5.9 nm to 21.4 nm were prepared by thermal decomposition of iron pentacarbonyl in the presence of oleic acid/octyl ether. The heating response of these ferromagnetic nanoparticles suspended in water were measured experimentally during which the same amount of iron nanoparticles and di-ionized water were irradiated by an alternating magnetic field and the increase in temperature of the system was measured. The heating performance of the nanoparticles was described in terms of Specific Absorption Rate (SAR) which depends on the heating rate. The heating rate was calculated from the initial slope of the heating curve at an inflection point whereby there is minimum heat loss to the surrounding. Results were analyzed to find the critical diameters for the transition from single-domain to superparamagnetic regime and from single-domain to multi-domain regime. Also, the frequency and current dependence of SAR were studied. The maximum value of SAR was obtained when the applied frequency and current were at 175 kHz and 15 A, respectively. An equation for the critical radius for the transition from single-domain to multi-domain regime with low anisotropy was derived and numerically solved by using a program written in C++ and results were analyzed to find the effect of surface parameters on the critical diameter of nanoparticles. The SAR as a function of nanoparticle’s diameter shows two maxima which can be connected with the two critical dimensions. One is DC1 at 18 nm for the transition from single-domain to multi-domain configuration and the second is DC2 at 10 nm for the transition from single-domain to superparamagnetic regime. Comparison of these experimental results with the bond order-length-strength correlation theory was discussed.
Magneto-Optical Evidence for Intrinsic Ferromagnetism in (Ga,Mn)As Layers Grown by Pulsed Laser Deposition
Authors: Gan’shina Elena A. , Golik L.L. , Kun’kova Z.E. , Kovalev Vitaly I. , Markin Yury V. , Novikov Andrey I. , Zykov Georgy S. , Danilov Yury A. , Kudrin Alexei V. , Vikhrova O.V. , Zvonkov B.N.
Published: July 2015

GaMnAs layers fabricated on GaAs(001) substrates by laser ablation technique were studied using the magneto-optical transversal Kerr effect (TKE) (E = 0.5 - 4.0 eV) and spectral ellipsometry (E = 1.4 - 4.5 eV). Obtained spectral, temperature and magnetic field TKE dependences shown that the used technique allowed us to obtain ferromagnetic (Ga,Mn)As layers, whose composition was close to single-phase one (without MnAs inclusions). Spectral dependences of the off-diagonal components (e’ = e’1 - ie’2) of the permittivity tensor and also of the magnetic circular dichroism (MCD) were calculated for ferromagnetic (Ga,Mn)As sample. The calculated dependences were compared with the published magneto-optical spectra of (Ga,Mn)As layers grown by molecular beam epitaxy.
Magnetism of Bismuth(III) Oxide-Based Compounds
Authors: Kravchenko Eleonora A.
Published: July 2015

209Bi NQR experiments, including analysis of zero-field line shapes, Zeeman-perturbed patterns and zero-field spin-echo envelopes were made to examine magnetic splitting of resonances revealed in the spectra of Main group element compounds of general composition BakBilAmOn (A=Al, В, Ge, Br, Cl). The results were explained assuming the existence in the compounds of ordered internal magnetic fields from 5 to 250 G which notably exceed those of nuclear magnetic moments. A dramatic (8−10-fold) increase in the resonance intensities, instead of broadening and fading, was observed for such compounds upon applying weak (below 500 Oe) external magnetic fields. The effect was shown to relate to the spin dynamics, namely, to the influence of external magnetic field on the nuclear spin-spin relaxation of the compounds with anomalous magnetic properties. In α-Bi2O3, paramagnetism depending on the thermal prehistory of a sample was found using SQUID-technique; magnetoelectric effect linear in magnetic field was also observed for this oxide.
Manifestation of Donor Hybridized Electron States in Magnetism of Nickel Impurities in Mercury Selenide Crystals
Authors: Govorkova T.E. , Gubkin A.F. , Lonchakov A.T. , Okulov Vsevolod I. , Andriichuk M.A. , Paranchich L.D.
Published: July 2015

The temperature dependences of the magnetic susceptibility χ (T) of diluted magnetic semiconductor HgSe:Ni (1·1018 < NNi < 1·1019) cm-3 were investigated. It was found that paramagnetic part of the susceptibility which is wholly due to the effect of the impurities in the range of temperature from 1.8 to 200 K is described by the Curie-Weiss law. The analysis of the concentration dependence of the Curie constant C(NNi) based on the model of the hybridized electronic states was carried out. The application of this model allowed us to determine the microscopic parameters of the electronic structure of these crystals (the effective spin of the hybridized electronic states at the nickel impurity Si and the resonance concentration of donor electrons n0d).
Synthesis and Magnetic Properties of β-Cu3Fe4(VO4)6 Single Crystals
Authors: Balaev Dmitry A. , Bayukov Oleg A. , Eremin Evgeniy V. , Molokeev M.S. , Pankrats Anatoly I. , Sablina K.A. , Velikanov Dmitry A. , Vorotynov A.M.
Published: July 2015

β-Cu3Fe4(VO4)6 single crystals were synthesized. The X-ray, magnetic, Mössbauer, and EPR investigations of the crystals were fulfilled. It is established that single-crystal β-Cu3Fe4(VO4)6 is a spin glass at low temperatures. Freezing temperature varies considerably depending on the orientation of the magnetic field relative to the crystal axes. Spin-glass state is confirmed by the relaxation of the magnetization.
Giant Magnetothermopower in Sm0.55Sr0.45MnO3 Manganite
Authors: Koroleva Liudmila I. , Morozov Artiom S. , Zhakina E.S.
Published: July 2015

Thermopower α and magnetothermopower ∆α/α were studied in the Sm0.55Sr0.45MnO3 samples, containing clusters of three types: ferromagnetic clusters with the Curie temperature TC = 126 K, A-type antiferromagnetic clusters with the Neel temperature TNA ≥ TC and CE-type antiferromagnetic clusters with the TNCE = 240 K. The curves of temperature dependence of α (T) have a large maximum including TC and TNCE and the sharp minimum on the {∆α/α}(T) curves in the TC-region. Negative magnetothermopower in minimum achieves the giant value ~ 85% in magnetic field 14.17 kOe. It is shown that thermopower is largely caused by the presence of ferromagnetic nanoclusters of ferron-type and to a lesser degree of CE-type antiferromagnetic clusters, in which there is a charge ordering, displacing oxygen ions.
Femtosecond Photo-Induced Phenomena in Multiferroic Hexagonal Manganite YMnO3
Authors: Pavlov Victor , Gridnev Valerii , Pisarev Roman , Pohl Martin , Akimov Ilya , Yakovlev Dmitri , Bayer Manfred
Published: July 2015

Transient optical anisotropy in the hexagonal manganite YMnO3excited by linearly and circularly polarized laser pulses has been observed. The photo-induced anisotropy was investigated by the pump-probe technique based on a femtosecond Ti:sapphire laser generating optical pulses at the photon energy of 1.55 eV. Temporal and spectral dependencies of the photo-induced optical rotation and ellipticity were analyzed by a theoretical model considering ultrafast population and relaxation processes near the interband transitions from the hybridized O2−(2p)-Mn3+(3d) (Γ1) to the Mn3+(3d3z2−r2) (Γ5) states at photon energies of the laser excitation. Very short relaxation time of ~10 fs, which is the Raman coherence time between the excited Γ5|x> and Γ5|y> states, has been determined. It is found that this coherence time is much shorter than a charge relaxation time of ~500 fs between the Γ5|x,y> and Γ1|g> states for the interband electronic transition Γ1→Γ5.
Influence of Different Interlayers on the Electrical and Magnetic Properties of Multilayered Structures Based on (Co41Fe39B20)33.9(SiO2)66.1 Composite
Authors: Kalinin Yuriy E. , Kashirin Maxim A. , Sitnikov Alexander V.
Published: July 2015

The dependences of the resistivity and complex magnetic permeability of (Co41Fe39B20)33.9(SiO2)66.1 composite–based multilayer films on the thickness of different metallic and semiconducting spacers are studied. It is found that in the presence of a continuous spacer with a resistivity on the order of 0.01 Ω·m, the superparamagnetic state of these heterogeneous systems changes to ferromagnetic ordering.
Influence of Rapid Quenching on Magnetocaloric Effect of Y2(Fe,Mn)17 Intermetallic Compounds
Authors: Zvonov Alexey I. , Pankratov N.Yu. , Karpenkov Dmitriy , Karpenkov Alexey , Nikitin S.A.
Published: July 2015

The melt-spun Y2(Fe,Mn)17ribbons were synthesized by rapid quenching from the melt. The phase composition, crystal structure and magnetocaloric effect (MCE) in low-cost iron-based pseudo-binary Y2(Fe,Mn)17ribbons were investigated respectively by using x-ray diffraction and direct measurements of MCE. It was found that crystal structure of the as-spun ribbons retains hexagonal Th2Ni17-type because of the weak glass-forming ability. The Y2Fe14Mn3and Y2Fe13Mn4nanostructured ribbons demonstrate higher MCE compare to polycrystalline alloys.
Magnetic and Magneto-Optical Research of Ni43.7Mn43.6In12.7 Ribbons
Authors: Novikov Andrey , Gan’shina Elena , Gonzalez-Legarreta Lorena , Prida V.M. , Hernando Blanca , Granovsky A.
Published: July 2015

We report the magnetic and magneto-optical (MO) properties of the Heusler Ni43.7Mn43.6In12.7 alloy ribbon in martensitic and austenitic states. The samples were produced by rapid solidification using the melt-spinning technique. The difference between the transformation temperatures obtained from magnetization and transverse Kerr effect (TKE) measurements shows that the chemical composition and/or microstructure are not identical in the bulk and at the ribbon surface. The TKE spectra profile in the spectral energy range of 0.5-3.5 eV does not change significantly at the martensitic transformation that indicates on a very similar electronic structure in martensitic and austenitic states.
Magnetic Phase Transitions and Magnetocaloric Effect in R2Fe17 (R = Y, Tb, Er)
Authors: Nikitin S.A. , Ovchenkova I.A. , Tskhadadze Georgiy A. , Skokov Konstantin P.
Published: July 2015

The direct measurements of the magnetocaloric effect (MCE) and the magnetization for R2Fe17 (R = Y, Tb, Dy) compounds are reported. The maximal values of the MCE for different R2Fe17 compounds are almost the same at the Curie temperature and are equal to 0.8 – 0.85 K at ΛH = 13.5 kOe. The field dependencies of the magnetization and MCE and the dependence of MCE via magnetization deviates from the classical regularities and describes by the thermodynamic theory attracting the higher terms. Obviously the occurrence of the mixed exchange interactions in these compounds leads to the requirement of consideration both thermal and local fluctuations of the exchange integrals near the magnetic transition temperature.
Magnetocaloric Effect of Gadolinium at Adiabatic and Quasi-Isothermal Conditions in High Magnetic Fields
Authors: Kamantsev Alexander P. , Koledov Victor V. , Mashirov Alexey V. , Dilmieva Elvina T. , Shavrov Vladimir G. , Cwik Jacek , Tereshina Irina S.
Published: July 2015

High cooling power of magnetocaloric refrigeration can be achieved only at large amounts of heat, which can be transferred in one cycle from cold end to hot end at quasi-isothermal conditions. The simple experimental method for direct measurement of the transferred heat from material with magnetocaloric effect (MCE) to massive nonmagnetic block at quasi-isothermal conditions was proposed. The vacuum calorimeter was designed for the simultaneous measurements of MCE both at adiabatic conditions (∆T) and quasi-isothermal conditions (∆Q) in the magnetic fields of Bitter coil magnet. This calorimeter was tested on samples of pure polycrystalline Gd with direct MCE. The maximal obtained values were ∆T = 17.7 K and ∆Q = 5900 J/kg at initial temperature 20 °C in magnetic field 140 kOe.
Magnetocaloric Properties of Cold Rolled Gd100-xZrx (x = 0, 1, 2, 3) Intermetallic Alloys
Authors: Taskaev Sergey , Skokov Konstantin , Karpenkov Dmitriy , Khovaylo Vladimir V. , Buchelnikov Vasiliy D. , Zherebtsov D.A. , Ulyanov Maxim , Bataev Dmitry , Galimov Damir , Pellenen Anatoliy
Published: July 2015

In this work we report the results of experimental investigation of the magnetocaloric effect in Gd100-xZrx(x= 0, 1, 2, 3) cold rolled ribbons. As it is shown the magnetocaloric effect exist within the large temperature interval 279-295 K and comparable with magnetocaloric effect observed on pure Gd. As it shown cold rolling is one of promising techniques for producing thin forms of magnetocaloric materials for heat exchangers of magnetic cooling devices.
Structural and Magnetic Properties of Mn2NiZ (Z = Ga, In, Sn, Sb) Heusler Alloys from Ab Initio Calculations
Authors: Sokolovskiy Vladimir V. , Zagrebin Mikhail A. , Sokolovskaya Y.A. , Buchelnikov Vasiliy D.
Published: July 2015

The structural and magnetic properties of Mn-based stoichiometric Heusler alloys have investigated by means of ab initio calculations in framework of the density functional theory. First principles electronic structure calculations have shown that Mn2NiZ (Z = Ga, In, Sn, Sb) alloys are ferrimagnets with antiparallel alignment between the Mn atoms. The martensitic transition can be realized in Mn2NiGa and Mn2NiSn alloys with tetragonal ratio of 1.27 and 1.16, respectively. Calculated properties are in a good agreement with available experimental data.
Structure, Electrical and Magnetic Properties of Ni47-xMn42+xIn11 (x=0, 1, 2) Based Heusler Alloys
Authors: Emelyanova S.M. , Marchenkov V.V. , Belozerova K.A. , Patrakov E.I. , Wang R.L. , Xiao H.B. , Yang C.P. , Weber Harald W. , Sauerzopf F. , Kaletina Yu.V.
Published: July 2015

Magnetic, magnetocaloric and transport properties of alloys of system Ni-Mn-In has been investigated. Large magnetocaloric effect have been observed at temperatures below room, making it a potential material system for various applications.
The Influence of Cold Rolling on Magnetocaloric Properties of Gd100-xYx (x = 0, 5, 10, 15) Alloys
Authors: Taskaev Sergey , Skokov Konstantin , Karpenkov Dmitriy , Khovaylo Vladimir V. , Buchelnikov Vasiliy D. , Zherebtsov D.A. , Ulyanov Maxim , Bataev Dmitriy , Pellenen Anatoliy , Fazlitdinova Alfiya
Published: July 2015

In this work we report the results of investigation of the magnetocaloric effect in Gd100-xYx (x= 0, 5, 10, 15) cold rolled ribbons. It is shown that the magnetocaloric effect exists within a wide temperature interval 258-295 K and it is comparable with the magnetocaloric effect observed in bulk samples of pure gadolinium. The value of the magnetocaloric effect in the rolled samples is reduced in comparison with the bulk samples and strongly depends on a degree of plastic deformation. High temperature heat treatment can restore a value of the magnetocaloric effect in the cold rolled ribbons up to initial ones. Thus, cold rolling is proposed to be a promising technique for producing thin forms of magnetocaloric materials for heat exchangers of magnetic cooling devices.
The Magnetocaloric Effect and Magnetic Transitions in Hydride Compounds: GdNiH3.2 and TbNiH3.4
Authors: Smarzhevskaya A.I. , Nikitin S.A. , Verbetsky Viktor N. , Iwasieczko Wacław , Golovanov Alexey N.
Published: July 2015

The paper presents the investigation of GdNiH3.2 and TbNiH3.4 hydrides magnetic transitions and magnetocaloric properties. The isothermal magnetization data in the fields up to 5T are obtained for GdNi and TbNi compounds and their hydrides and the values of magnetic entropy change are calculated. The maximum values of magnetic entropy change ΔSM in GdNiH3.2 and TbNiH3.4 are extremely large. It is shown that the hydrogenation shifts ΔSM(T) maximum to lower temperatures.
Spin Fluctuations in Disordered Metallic Ferrimagnetic Alloys
Authors: Grebennikov Vladimir I. , Radzivonchik Danil I.
Published: July 2015

We propose a theory for the quantitative description of the thermodynamic, magnetic and electronic properties of disordered alloys of transition metals and normal, for example, the system Fe-Al, as obtained from melting, and in the form of metastable states produced by mechanical grinding. System of itinerantd-electrons with two constants of the intra-atomic exchange interaction is investigated by the fluctuating field approach. Fundamentally new feature of the system is the presence of several ferrimagnetic solutions, transitions between which give variety to the temperature dependence of the magnetic characteristics of disordered alloys. Results of calculation of the temperature dependences of the magnetic characteristics of iron aluminum alloys are considered as an application of the theory.
Monte Carlo Study of the Polycrystalline Ni2MnGa Heusler Alloy
Authors: Pavlukhina O.O. , Sokolovskiy V.V. , Buchelnikov Vasiliy D.
Published: July 2015

In this work, we report on the theoretical calculations of the temperature dependence of magnetization in Ni2MnGa alloy by Monte Carlo simulation. The calculations have been carried out for the single crystal and polycrystalline structures with 16, 32 and 64 magnetic domains. The theoretically calculated results are in good agreement with the experimental data.
Influence of the Defects on Magnetic Properties of Glass-Coated Microwires
Authors: Zhukova Valentina , Shuvaeva Evgenia , Churyukanova Margarita , Kaloshkin Sergei , Talaat Ahmed , Ipatov Mihail , Zhukov Arcady
Published: July 2015

Using magnetic characterization, electronic and optical microscopy we studied magnetic properties and different kind of defects in glass-coated microwires containing Co. We observed that Co addition allows improvement of magnetic softness. We also observed the oxygen presence in “defective” regions on the metallic nucleus surface and indications of chemical interaction between the glass-coating and the metallic nucleus.
Effects of a Superparamagnetic State of Particles of a Paraffin Based Magnetic Colloid
Authors: Dikansky Yury , Ispiryan Anna , Kunikin Stanislav , Radionov Alexandr
Published: July 2015

Temperature dependence of the low-frequency complex magnetic susceptibility of magnetic colloid with paraffin as a dispersion medium has been studied. When interpreting the obtained results, the specific features of the magnetic moment relaxation of single-domain particles and the possibility of changing of relaxation mechanism from Neel to Brownian have been considered.
The Investigation of Critical Properties of the Transition from Modulated Phase into Paramagnetic Phase
Authors: Murtazaev A.K. , Ibaev Zhavrail G.
Published: July 2015

The anisotropic Ising model with competing interactions in the region of transition from a modulated phase into paramagnetic state is investigated by the Monte-Carlo methods. By means of histogram analysis and the finite-size scaling method, the modulated – paramagnetic phase transition is shown to be a second order phase transition. Critical parameters and temperatures of phase transitions in this region are calculated.
Magnetic Properties of PrхY1-xFe3(BO3)4
Authors: Pankrats A.I. , Demidov A.A. , Velikanov D.A. , Tugarinov V.I. , Temerov V.L.
Published: July 2015

The magnetic properties of trigonal PrxY1-xFe3(BO3)4 compound have been investigated. Anomalies on the magnetization curves induced by a magnetic field are observed for each composition. The calculations were performed using a molecular-field approximation and a crystal-field model for the rare-earth subsystem. Extensive experimental data on the magnetic properties of PrxY1-xFe3(BO3)4 have been interpreted and good agreement between theory and experiment has been achieved.
Universal Hysteresis Behavior of Double Perovskite Ba2-xLaxFeMoO6
Authors: Handoko Djati , Dang Thanh Tran , Nanto Dwi , Yu Seong Cho , Oh Suhk Kun , Kim Dong Hyun , Demyanov S.E. , Kalanda N.A. , Petrov A.V. , Yarmolich M.V. , Kovalev L.V.
Published: July 2015

We have investigated temperature-dependent magnetic hysteresis loop behavior of Ba2-xLaxFeMoO6 with double perovskite structure by means of a vibrating sample magnetometer (VSM). As partial substitution of Ba2+ by La3+ is varied from x = 0.1 to 0.3, TC is found to increase from 324 to 345 K. Interestingly, however, hysteresis loop area, remanent magnetization, and coercivity are found to follow a universal behavior with respect to a temperature variation regardless of the Ba2+ substitution.
Magnetic and Magnetoelectric Properties of Sm1-xLaxFe3(BO3)4 Single Crystals
Authors: Eremin Evgeniy V. , Volkov Nikita V. , Gudim Irina A. , Temerov Vladislav L.
Published: July 2015

Sm1-xLaxFe3(BO3)4(х = 0, 0.5, and 0.75) single crystals are grown by the flux method and their characteristics are investigated in the temperature range 5−300 K and magnetic fields of up to 9 T. It is established that substitution of nonmagnetic La3+ions for magnetic Sm3+ions increases the magnetic moment and weakens the magnetoelectric effect in Sm1-xLaxFe3(BO3)4.
Monte Carlo Modelling of Two Dimensional Multiferroics
Authors: Lamekhov S.J. , Bychkov Igor V. , Kuzmin Dmitry A. , Shavrov Vladimir G.
Published: July 2015

Properties of two dimensional multiferroic with magnetic and electric order was studied on two-dimensional lattice with size 20x20. As a result of modeling was found temperature dependencies of polarization, magnetization and dielectric, magnetic and magnetoelectric susceptibilities for different values of magnetoelectric coefficients. Modeling shows influence of external fields on phase transitions through magnetoelectric effect. Magnetoelectric coupling leads to shift in temperature of phase transition.
The Correlations between Dynamic Interactions in Antiferromagnetic Multiferroics
Authors: Kharrasov Muhamed Kh. , Kyzyrgulov Ilgiz R. , Sharafullin Ildus F. , Nugumanov Aidar G.
Published: July 2015

In this work we have researched the features of dynamic magnetoelectric and magnetoelastic interactions in multiferroic crystal, influenced by various external fields, with the group of symmetry . Based on the integrated approach, which combines N. N. Bogolyubov’s quantum-statistic methods, Green’s temperature functions, diagram technique and symmetry, energy spectrum’s and static spin susceptibility’s dependences on the temperature and external fields were calculated. The effective parameters of magnetoelectric and magnetoelastic interactions dependences on the external fields’ intesities were analysed. It is shown that these parameters have a distinct maximum in the resonance value. As was shown, it is possible to enhance the interactions between spins, ferroelectric and fonons subsystems in multiferroics by applicating the external fields in different crystallographic directions.