Temperature Dependences of the Magnetic Susceptibility of Water-Based Magnetic Fluids

2020 ◽  
Vol 9 (2) ◽  
pp. 90-97
Author(s):  
Yury I. Dikansky ◽  
Anna G. Ispiryan ◽  
Stanislav A. Kunikin ◽  
Maxim Zakharzhevskii ◽  
Andrey S. Drozdov
Keyword(s):  
Phase Transition ◽  
Magnetic Susceptibility ◽  
Colloidal Particles ◽  
Disperse Medium ◽  
Magnetic Fluids ◽  
Water Phase ◽  
Solidification Temperature ◽  
Dispersed Particles ◽  
Water Based ◽  
Temperature Dependences

This paper presents the results of a study of the temperature dependences of the magnetic susceptibility of water-based magnetic fluids (magnetic colloids) with magnetite particles stabilized by their electrostatic interaction. The average size of dispersed particles was 8 nm, and the volume concentration of particles in the selected samples under study was 1.4% and 1.6%. The investigations were carried out over a wide temperature range. The temperature dependence of the susceptibility, for the first time, was obtained in the region of the colloidal phase transition under supercooling of the dispersion medium (water). Significant differences were found between the temperature dependences of the magnetic susceptibility of such magnetic fluids, where as similar dependences have been found for the susceptibility of magnetic hydrocarbon-based fluids. The observed behavior of such dependences near the water phase transition temperature is determined by the changes in the water phase state, heat release and structuring of the colloid as a result of water crystallization. Moreover, it is suggested that a certain impact on the dependence behavior in the region of the colloidal solidification temperature can also come from the process of blocking the Brownian degrees of freedom of a small fraction of large dispersed particles. It is concluded that the observed maxima in the investigated susceptibility temperature dependences in the lower temperature region are due to magnetic transformations in the colloidal zones formed at the solidification front of the disperse medium with a dense packing of single-domain colloidal particles.

Mössbauer Studies of Fe2+ in Iron Langbeinites and other Crystals with Langbeinite Structure

1998 ◽  
Vol 53 (1-2) ◽  
pp. 27-37 ◽  
Author(s):  
M. Windhaus ◽  
B. D. Mosel ◽  
W. Müller-Warmuth
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
High Temperature ◽  
Low Temperature ◽  
High Spin State ◽  
Cubic Phases ◽  
Debye Temperatures ◽  
Phase Transition Temperatures ◽  
Abrupt Changes ◽  
Temperature Dependences

Abstract 57 Fe Mössbauer spectra have been measured at various temperatures between 4.2 K and 300 K for iron langbeinites A 2 Fe 2^04)3 with A = K, NH 4 , Rb, T1 and magnesium, manganese and cadmium lang-beinites doped with Fe" + . The spectra revealed several contributions whose isomer shifts and quadru-pole splittings have been obtained by fitting program routines. For the high-temperature cubic phases two crystallographically non-equivalent iron sites have been identified, characteristic of Fe2+ in the high-spin state. Abrupt changes of the quadrupole couplings indicated phase transitions; in some cases, the spectra have also revealed several sites for Fe2+ in low temperature phases. From the temperature dependences, phase transition temperatures, crystal field splittings and Debye temperatures have been derived.

Laser-Induced Pretransitional Ordering And Nonlinear Optical Properties Of Rigid-Rod Polymer Suspensions

1993 ◽  
Vol 328 ◽  
Author(s):  
Boris E. Vugmeister ◽  
Michelle S. Malcuit ◽  
John C. Kralik ◽  
Colleen Stevens
Keyword(s):  
Phase Transition ◽  
Colloidal Particles ◽  
Volume Fraction ◽  
Orientational Order ◽  
Critical Value ◽  
Orientational Relaxation ◽  
First Order ◽  
First Order Phase Transition ◽  
Rigid Rod ◽  
First Order Phase

ABSTRACTWe investigate the pretransitional behavior in laser-induced alignment of rigid rod-like polytetraflouroethylene (PTFE) suspensions. Using a laser-induced birefringence experiment, we measure both the orientational order parameter and the orientational relaxation time. We find that both increase as the volume fraction of colloidal particles approaches the critical value for the isotropic-nematic phase transition. Experimental results are compared with theory which takes into account the possibility of a first-order phase transition induced by a laser electric field.

scholarly journals Поведение керамических твердых растворов 33PbYb-=SUB=-1/2-=/SUB=-Nb-=SUB=-1/2-=/SUB=-O-=SUB=-3-=/SUB=--22PbZrO-=SUB=-3-=/SUB=--45PbTiO-=SUB=-3-=/SUB=- в электрическом поле

2020 ◽  
Vol 46 (6) ◽  
pp. 31
Author(s):  
Л.С. Камзина ◽  
G. Li
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Electric Field ◽  
Electric Fields ◽  
Dielectric Parameters ◽  
Morphotropic Phase Transition ◽  
Temperature Dependences ◽  
Pseudocubic Phase

The temperature dependences of the dielectric parameters were studied, as well as the changes in the dielectric constant with time in ceramic 33PbYb1 / 2Nb1 / 2O3-22PbZrO3-45 PbTiO3 samples in electric fields (0 <E <8 kV / cm). It is shown that in the phase existing below the temperature of the morphotropic phase transition, in addition to the rhombohedral and tetragonal phases, a small fraction of the relaxor pseudocubic phase is present. It was found that, unlike other relaxors, the dielectric constant practically does not change with time when an electric field is applied in the phase below the temperature of the morphotropic phase transition. Possible reasons for this behavior are discussed.

scholarly journals Impulsively-Laser Excitation and Propagation of Ultrasonic Waves through Nanomagnetic Fluid

2021 ◽  
Vol 12 (3) ◽  
pp. 211-219
Author(s):  
A. R. Baev ◽  
A. I. Мitkovets ◽  
M. V. Asadchaya ◽  
A. L. Mayorov
Keyword(s):  
Laser Radiation ◽  
Boundary Conditions ◽  
Magnetic Fluid ◽  
Colloidal Particles ◽  
Laser Excitation ◽  
Magnetic Fluids ◽  
Ultrasonic Waves ◽  
Dispersed Phase ◽  
Transformation Mechanism ◽  
Sedimentation Stability

Magnetic fluids belong to the class of nanomaterials with a high gain of light absorption, aggregative and sedimentation stability as well as controllability by external fields, which is of interest to use in the field of optoacoustics. The purpose of the work was to experimentally study the effect of the optoacoustic transformation in a magnetic fluid, depending on the concentration of magnetic colloidal particles, boundary conditions, intensity of the laser as well as to identify the possibilities of using the magnetic fluid as an element of the optoacoustic transformation in a number of applications.A brief analysis of the optoacoustic transformation mechanism in a magnetic fluid was carried out and a technique and an installation that implements the shadow measurement variant developed. A Lotis type laser was used as a source of ultrasonic pulse-laser excitation in magnetic fluids. A quartz and air were used as a material transmitting the energy of laser radiation in a magnetic fluid. Receiving of ultrasound signals was made by a piezoelectric probe at a working frequency of 5 MHz. In the measurement process, the concentration of the dispersed phase in tmagnetic fluid was varied from zero to 8 % and the energy in the impulse – from zero to 10 mJ.For the first time, it was established that: a) an amplitude of the function of the optoacoustic transformation in a magnetic fluid, depending on the concentration of the dispersed phase, has a maximum determined by the fluid physical properties and boundary conditions; b) for all samples within the measurement error, a quasilinear dependence of the specified amplitude of energy in the laser pulse in the range of 0–8 MJ has been established.A number ways of the optoacoustic effects in magnetic fluids to use in ultrasonic testing, measuring the intensity of the laser radiation had been suggested.

scholarly journals Температурные зависимости электропроводности и магнитной восприимчивости кристаллов твердых растворов Sb-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=--Bi-=SUB=-2-=/SUB=-Te-=SUB=-3-=/SUB=-

2021 ◽  
Vol 55 (12) ◽  
pp. 1162
Author(s):  
Н.П. Степанов ◽  
В.Ю. Наливкин ◽  
А.К. Гильфанов ◽  
А.А. Калашников ◽  
Е.Н. Трубицына
Keyword(s):  
Electrical Conductivity ◽  
Magnetic Susceptibility ◽  
Solid Solutions ◽  
Thermoelectric Materials ◽  
Materials Science ◽  
Practical Importance ◽  
Experimental Studies ◽  
Electronic System ◽  
Temperature Dependences ◽  
The Subject

Solid solutions Bi2Te3-Sb2Te3 continue to be the subject of numerous and versatile experimental studies due to their practical importance for thermoelectric materials science. In this regard, the problem of studying the regularities of changes in the state of the electronic system of these semiconductors from composition and temperature remains urgent. This paper presents the results of studying the temperature dependences of the magnetic susceptibility of Bi2Te3-Sb2Te3 crystals containing 10, 25, 40, 50, 60 mol. % Sb2Te3. The correlation of the behavior of the temperature dependences of the magnetic susceptibility and electrical conductivity is analyzed.

scholarly journals Растворимость теллура в кристаллах TlGaTe-=SUB=-2-=/SUB=-, TlInTe-=SUB=-2-=/SUB=- и электрофизические свойства твердых растворов

2018 ◽  
Vol 60 (9) ◽  
pp. 1656
Author(s):  
А.И. Наджафов ◽  
Н.А. Алиева ◽  
К.Г. Халилова
Keyword(s):  
Phase Transition ◽  
Electrical Conductivity ◽  
Solid Solutions ◽  
Physicochemical Analysis ◽  
Lattice Parameters ◽  
Temperature Dependences ◽  
Complex Methods

AbstractThe complex methods of the physicochemical analysis are used to study TlGaTe_2–Te and TlInTe_2–Te alloys in which the tellurium solubility region up to 5.0 at % is observed. The temperature dependences of the lattice parameters and the electrical conductivity of TlGaTe_2 + x and TlInTe_2 + x have been studied in different crystallographic directions. The TlGaTe_2 + x and TlInTe_2 + x solid solutions undergo a phase transition at a temperature of 498 K. The transition nature is interpreted.

scholarly journals Mixed-order phase transition in a colloidal crystal

2017 ◽  
Vol 114 (49) ◽  
pp. 12906-12909 ◽  
Author(s):  
Ricard Alert ◽  
Pietro Tierno ◽  
Jaume Casademunt
Keyword(s):  
Phase Transition ◽  
Phase Transitions ◽  
Colloidal Particles ◽  
Colloidal Crystal ◽  
Equilibrium Phase ◽  
Mean Field ◽  
Critical Dimension ◽  
Colloidal System ◽  
Test Bed ◽  
Mixed Order

Mixed-order phase transitions display a discontinuity in the order parameter like first-order transitions yet feature critical behavior like second-order transitions. Such transitions have been predicted for a broad range of equilibrium and nonequilibrium systems, but their experimental observation has remained elusive. Here, we analytically predict and experimentally realize a mixed-order equilibrium phase transition. Specifically, a discontinuous solid–solid transition in a 2D crystal of paramagnetic colloidal particles is induced by a magnetic field H. At the transition field Hs, the energy landscape of the system becomes completely flat, which causes diverging fluctuations and correlation length ξ∝|H2−Hs2|−1/2. Mean-field critical exponents are predicted, since the upper critical dimension of the transition is du=2. Our colloidal system provides an experimental test bed to probe the unconventional properties of mixed-order phase transitions.

scholarly journals III-1　Dynamics of Confined Water Phase Transition of Supercooled Water

RADIOISOTOPES ◽  
2014 ◽  
Vol 63 (6) ◽  
pp. 331-342
Author(s):  
Toshio YAMAGUCHI ◽  
Koji YOSHIDA
Keyword(s):  
Phase Transition ◽  
Supercooled Water ◽  
Water Phase ◽  
Confined Water

Field and temperature dependences of anisotropic magnetic susceptibility of CaNdAlO/sub 4/ crystal

1994 ◽  
Vol 30 (2) ◽  
pp. 1012-1014 ◽  
Author(s):  
J. Fink-Finowicki ◽  
R. Puzniak ◽  
M. Baran ◽  
P. Byszewski ◽  
M. Gutowski ◽  
...  
Keyword(s):  
Magnetic Susceptibility ◽  
Temperature Dependences
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