scholarly journals Особенности доменной структуры гексаферрита BaFe-=SUB=-12-=/SUB=-O-=SUB=-19-=/SUB=- вблизи температуры Кюри

2020 ◽  
Vol 62 (7) ◽  
pp. 1050
Author(s):  
А.А. Безлепкин ◽  
С.П. Кунцевич
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Domain Walls ◽  
Physical Mechanism ◽  
Structural Features ◽  
Temperature Range ◽  
The Difference ◽  
Increasing Temperature ◽  
Curie Temperature Tc ◽  
Ordered State

The structural features of the domain walls of the BaFe12O19 hexaferrite near the Curie temperature TC = 724 K were studied. The studies were performed on single-crystal samples in an alternating magnetic field with a frequency of 73 MHz and 71 MHz with a constant magnetic field in the range 0–0.25 kOe. In BaFe12O19 at a temperature of T1 = 716 K, the magnetic structure of the domain walls changes – the Bloch walls transform into linear walls with increasing temperature. The value ΔТ = Tc – T1≈8 K. The physical mechanism considered in the work, which determines the difference between the temperature range of the existence of the magnetically ordered state and the temperature range of the existence of the Bloch domain walls, is consistent with experimental results. The estimated calculation of the criterion for the transition of the Bloch domain wall to a linear wall at T1 = 716 K corresponds to the obtained experimental data.

Interaction of Tops of Domains in Metal Nano of the Film

2019 ◽  
Vol 945 ◽  
pp. 771-775 ◽  
Author(s):  
V.P. Panaetov ◽  
Denis B. Solovev
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Film Thickness ◽  
Magnetic Structure ◽  
Domain Walls ◽  
Magnetic Moments ◽  
Ferromagnetic Film ◽  
Easy Magnetization ◽  
Electron Transmission ◽  
Transmission Microscope

Ferromagnetic film can be a matrix for recording information with the help of magnetic moments of electrons. The study of the processes of changing the magnetic structure in an electron-transmission microscope makes it possible to investigate micro magnetic phenomena. In this paper, we investigate the interaction between the vertices of neighboring regions. It is shown how the magnetic structure of the vertices of the domains changes as they approach each other with the help of an increasing constant magnetic field applied along the axis of easy magnetization. The distance was measured between the vertices of the domains. The schemes of distribution of the magnetization vectors between interacting vertices are shown. These schemes are made from experimental images of the magnetic structure. The distances between domain vertices and domain walls were compared on the basis of experimental data. The film thickness is 50 nm; the structure is Ni0.83-Fe0.17. The films were obtained by the method proposed by us. From the experimental results it follows that the interaction of the domain walls is observed at a distance of 20 microns and the interaction of the domain vertices is manifested at a distance of 100 μm.

scholarly journals Experimental Study on Wet Skid Resistance of Asphalt Pavements in Icy Conditions

Materials ◽  
2019 ◽  
Vol 12 (8) ◽  
pp. 1201 ◽  
Author(s):  
Yan ◽  
Mao ◽  
Zhong ◽  
Zhang ◽  
Zhang
Keyword(s):  
Surface Friction ◽  
Melting Process ◽  
Asphalt Pavements ◽  
Skid Resistance ◽  
Ice Melting ◽  
Temperature Range ◽  
Bitumen Emulsion ◽  
Image Measure ◽  
The Difference ◽  
Increasing Temperature

In this research, the durability of skid resistance during the ice melting process with temperature increasing from −5 °C to 10 °C was characterized by means of a British Pendulum Skid Tester. Four types of pavement surfaces were prepared and tested. The difference between two antiskid layers prepared with bitumen emulsion was the aggregate. The detailed angularity and form 2D index of fine aggregates used for antiskid surfaces, characterized by means of the Aggregate Image Measure System (AIMS) with micro image analysis methods, were then correlated with British Pendulum Number (BPN) values. Results indicate that skid resistance has the lowest value during the ice-melting process. The investigated antiskid layers can increase the surface friction during icy seasons. In icy conditions, the skid resistance behavior first worsens until reaches the lowest value, and then increases gradually with increasing temperature. Results from ice-melting conditions on four investigated pavement surfaces give the same temperature range where there will be lowest skid resistance. That temperature range is from 3 °C to 5 °C. A thicker ice layer will result in a lower skid resistance property and smaller “lowest BPN”.

Microwave Responce from La- and Dy- doped BiFeO3 Thin Films

2006 ◽  
Vol 966 ◽  
Author(s):  
Peter Kr. Petrov ◽  
Vaijayanti R Palkar ◽  
Neil McN Alford ◽  
Alexander K Tagantsev ◽  
K Prashanthi ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thin Films ◽  
Dielectric Response ◽  
Domain Walls ◽  
Structural Features ◽  
Type I ◽  
Microwave Frequencies ◽  
Bifeo3 Thin Films ◽  
Electric And Magnetic Fields ◽  
Exact Origin

ABSTRACTThe dielectric response of La- and Dy- doped BiFeO3 thin films to electric- and magnetic fields was measured at microwave frequencies (up to 12GHz) in a temperature range from 25 °C to 300 °C. Interesting phenomena were observed. Significant oscillations in the C(f) characteristic which were unaffected by the electric field or by elevated temperature but which were dampened by a magnetic field. We also observed ‘N’-type I-V characteristics. A possible explanation for this mesoscopic response is the presence of structural features that cause resonance (e.g. grains, grain-boundaries, domains, domain walls etc), with a contribution strong enough to be averaged by the system. The exact origin of these features is unknown at present.

g-Values for γ-irradiated water as a function of temperature

1990 ◽  
Vol 68 (5) ◽  
pp. 712-719 ◽  
Author(s):  
A. John Elliot ◽  
Monique P. Chenier ◽  
Denis C. Ouellette
Keyword(s):  
Experimental Data ◽  
Hydrogen Peroxide ◽  
Hydroxyl Radical ◽  
Temperature Dependence ◽  
Atomic Hydrogen ◽  
Molecular Hydrogen ◽  
Hydrated Electron ◽  
Temperature Range ◽  
Increasing Temperature

The g-values of primary species formed in the γ-radiolysis of water have been estimated for the temperature range 25–300 °C. The g-values for the hydrated electron, the hydroxyl radical, and molecular hydrogen all increase approximately 50% over this temperature range. The g-values for the minor products, hydrogen peroxide and atomic hydrogen, probably also increase with temperature; however, there is evidence from some of the experimental data which suggests that these g-values may slightly decrease with increasing temperature. Keywords: radiolysis, g-values, temperature dependence.

Phonon properties of delafossite multiferroic compound CuFeO2. Comparison with CuCrO2

2019 ◽  
Vol 33 (12) ◽  
pp. 1950141
Author(s):  
A. T. Apostolov ◽  
I. N. Apostolova ◽  
J. M. Wesselinowa
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
Phase Transition ◽  
Dopant Concentration ◽  
Phonon Energy ◽  
Function Technique ◽  
Ion Doping ◽  
Increasing Temperature ◽  
The Magnetic Field ◽  
Phonon Properties

The temperature, magnetic field and ion doping dependence of the phonon properties of CuFeO2 are studied on the basis of a microscopic model and using Green’s function technique. The phonon energy decreases with increasing temperature, whereas the phonon damping increases. There is a kink at the phase transition temperature [Formula: see text] which shows the influence of the magnetic field on the phonon properties. The kinks vanish by applying an external magnetic field. By doping of ions with different radius compared to the Fe ion, the phonon energy in CuFeO2 can increase (Ga) or decrease (Sc) with increasing dopant concentration, whereas the damping is always enhanced. The results are compared with those of CuCrO2. Some discrepancies in the literature are discussed. The observed results are in qualitative agreement with the experimental data.

Ultrasonic study of liquid-quenched sulfur from room temperature to 200 °C

1994 ◽  
Vol 9 (12) ◽  
pp. 3170-3173 ◽  
Author(s):  
Akira Doi ◽  
Satoru Kariya ◽  
Hiroaki Kamioka
Keyword(s):  
Thermal Analysis ◽  
Room Temperature ◽  
Polymerization Process ◽  
Structural Units ◽  
Ultrasonic Study ◽  
Temperature Range ◽  
The Difference ◽  
Increasing Temperature

When liquid S is heated above 159 °C, the S8 rings (which are the dominant structural units below this temperature) break open and polymerize into helical chains (S∞). Therefore, samples quenched from liquids at temperatures above or below 159 °C would be different in various properties by the difference in the amount of S∞. The present ultrasonic study of liquid-quenched S in the temperature range from room temperature to 200 °C has revealed this difference. It has been demonstrated that ultrasonics is as powerful as a conventional thermal analysis in dealing with the variation of a material with increasing temperature, even though both techniques were found to be relatively insensitive to the polymerization process.

scholarly journals Reduction kinetics of lead-rich slag with carbon in the temperature range of 1073 to 1473K

2013 ◽  
Vol 49 (2) ◽  
pp. 201-206 ◽  
Author(s):  
X. Hou ◽  
K.C. Chou ◽  
B. Zhao
Keyword(s):  
Activation Energy ◽  
Reaction Rate ◽  
Graphite Crucible ◽  
Reduction Reaction ◽  
Synthetic Slag ◽  
Reduction Kinetics ◽  
Temperature Range ◽  
Diffusion Controlled ◽  
The Difference ◽  
Increasing Temperature

Extensive experiments have been carried out on the reduction of lead-rich slag in graphite crucible at temperature range of 1073 to 1473K. The reduction kinetics was also compared between industrial sinters and synthetic slags. The extent of reduction was measured by the volume of CO-CO2 gas produced at a given temperature and time. It was found that, at a given temperature, the reaction rate between the slag and carbon was initially fast and then slow as the extent of the reaction increases. Only limited reaction between slag and carbon occurred at temperatures below 1173K. At temperatures above 1173K, the reaction rate increased significantly with increasing temperature. The reduction reaction was found to be mainly liquid-solid reaction, which was chemically controlled at initial stage and diffusion controlled at later stage. The apparent activation energy was calculated to be 83.8 kJ/mol at chemically controlled stage and 224.9 kJ/mol at diffusion controlled stage for reduction of industrial sinter. For the synthetic slag, the reaction activation energy was 102.9 kJ/mol at chemically controlled stage and 259.4 kJ/mol at diffusion controlled stage. The difference of the activation energy between industrial sinter and synthetic slag can be explained by the difference in their CaO/SiO2 ratios.

Imaging of ferroelectric domain walls by electron holography

1992 ◽  
Vol 50 (1) ◽  
pp. 246-247
Author(s):  
Xiao Zhang
Keyword(s):  
Magnetic Field ◽  
High Resolution ◽  
Domain Walls ◽  
Ferroelectric Domain ◽  
Object Wave ◽  
Electron Holography ◽  
High Resolution Imaging ◽  
Quantitative Measurements ◽  
Resolution Imaging ◽  
Electron Microscopes

Electron holography has recently been available to modern electron microscopy labs with the development of field emission electron microscopes. The unique advantage of recording both amplitude and phase of the object wave makes electron holography a effective tool to study electron optical phase objects. The visibility of the phase shifts of the object wave makes it possible to directly image the distributions of an electric or a magnetic field at high resolution. This work presents preliminary results of first high resolution imaging of ferroelectric domain walls by electron holography in BaTiO3 and quantitative measurements of electrostatic field distribution across domain walls.

scholarly journals A Magneto-Active Elastomer Crawler with Peristaltic and Caterpillar Locomotion Patterns

Actuators ◽  
2021 ◽  
Vol 10 (4) ◽  
pp. 74
Author(s):  
Tsam Lung You ◽  
Hemma Philamore ◽  
Fumitoshi Matsuno
Keyword(s):  
Magnetic Field ◽  
Experimental Data ◽  
External Magnetic Field ◽  
Mathematical Models ◽  
Confined Spaces ◽  
Low Mass ◽  
Structural Simplicity

In this work we present a soft crawler fabricated using a magneto-active elastomer. The crawler is controlled by an external magnetic field to produce two locomotion patterns: peristaltic and caterpillar crawling. Due to its structural simplicity, low mass, wirelessly controlled actuation and compliant body the design of this crawler has the potential to address the key challenges faced by existing crawling robots. Experimental data were gathered to evaluate the performance of the crawler locomotion in a pipe. The results validated the mathematical models proposed to estimate the distance traveled by the crawler. The crawler shows potential for use in exploration of confined spaces.

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