Ferrite Ferrofluids Research Articles

Advance effect of magnetic field on the rheological properties of manganese zinc ferrite ferrofluid

The rheological characteristics of manganese zinc (Mn-Zn) ferrite magnetic nanofluid synthesized using co-precipitation technique were examined in the absence and presence of magnetic fields. The research formulates required conditions needed for the formation of a gelly-like structure. The impact of magnetic field and temperature on the rheological properties of Mn-Zn ferrite ferrofluid is investigated. When a magnetic field was applied, higher magnetoviscoelasticity and magnetoviscosity were formed. Analysis was also done on other rheological parameters, such as the damping factor, which is crucial for regulating and restricting vibrations in a system. A stiff, gel-like structure is produced when a magnetic field is applied, and the gel-like quality grows as the magnetic field increases; when the magnetic field is removed, the gel-like and rigidity of the structure is lost. At low temperatures, the liquid phase is dominated by solid-like particles, whereas at high temperatures, the liquid-like structure is dominant. This study reveals the conditions required for the creation of high viscous effect and the viscoelastic behavior induced by the field offers important insights for optimizing the Mn-Zn ferrite ferrofluid for a range of applications. Other criterial for gel-like structure formation such as low torque and deflection angle of the ferrofluid were also established.

Modeling and Simulation of a High-Performance Magnetic Biosensor for Biomedical Sensing

The current magnetic-based biosensor technologies are expensive and intricate, making them unsuitable for meeting the requirements of point-of-care medical diagnosis. This research introduces a straightforward magnetic biosensor architecture that includes an L-shaped ferromagnetic core with UL dimensions. The design involves an air gap being replaced with highly porous aluminum or copper foam, offering a potentially cost-effective and uncomplicated solution for point-of-care diagnosis based on the magnetic field effect. The foam serves as a medium for hosting biological samples, such as proteins and DNA, which are labeled with high-permeability ferromagnetic nanoparticles. The biosensor operates by detecting labeled biological molecules through magnetic field interactions. The electrical parameters of the system underwent methodical optimization to enhance overall performance. The investigation delved into the influence of various materials on the magnetic properties of the air gap. It also examined the relationships between permeability, output-induced voltage, input voltage, and input frequency. The findings reveal that utilizing materials with elevated magnetic permeability, such as Magnetite (Fe3 O4 ) or Cobalt ferrite (CoFe2 O4 ) ferrofluids, significantly enhances the biosensor's performance by optimizing magnetic coupling between primary and secondary windings. This innovative magnetic biosensor exhibits potential applications in diverse fields, including molecular biology and medical diagnostics. The study contributes valuable insights into the design and optimization of magnetic biosensors, offering opportunities for heightened sensitivity and selectivity in the detection of ferromagnetic nanoparticles labeled biomolecules such as DNA or proteins.

Single domain soft ferromagnetic ferrofluid suitable for intratumoural magnetic hyperthermia

Magnetic hyperthermia is an effective modality for treating cancerous cells selectively at the intracellular level via proper administration, surface tagging and appropriate choice of magnetic nanoparticle. Also, achieving the therapeutic temperature with as much low concentration of nanoparticles, as possible, is desirable. Recently, ferromagnetic nanoparticles or ferrofluid are gaining attention as effective magnetic hyperthermia agents due to their enhanced heating potential under in vivo conditions. In the present work, we have fabricated citrate capped cobalt ferrite ferrofluid via a simple two-step process and investigated the physicochemical, magnetic and induction heating performance. The average size of the synthesized nanoparticle is 9 ± 4.3 nm which is suitable for intracellular hyperthermia and has the advantage that it can be easily eliminated from the body through renal clearance. The M(T) measurement of the ferrofluid confirmed the soft ferromagnetic behavior. The induction heating potential of the ferrofluid prepared was tested at different concentrations (1, 2, 5 & 10 mg/ml), suspension medium and alternating magnetic fields (15, 30 & 45 kA/m) with a fixed frequency of 316 kHz. Under a viscous environment, 1 mg/ml sample subjected to 45 kA/m reached the hyperthermia temperature within 160 s and the specific loss power was found to be 297 W/g(Co+Fe). Hence, the synthesized ferrofluid is suitable for intratumoural hyperthermia.

Characteristics of temperature-dependent shear flow in an ultrasonicated ferrofluid

The rheological effect of manganese zinc (Mn-Zn) ferrite ferrofluid was studied and the impact of temperature on the magnetoviscosity and viscoelastic system of manganese-zinc ferrite ferrofluid generated by co-precipitation process is investigated. At 25 ◦C, a ferrofluid structure that is both hard and elastic is produced. As the temperature rises, the fluid structure loses its elasticity and becomes semi-rigid. When a low relaxation modulus is applied, the fluid behavior, which is temperature-dependent, exhibits the development of linear stress relaxation and steady state flow. When a greater relaxation modulus is used, non-steady state flow results. At a high temperature of 50 ◦C, steady state flow is quickly obtained, whereas at a low temperature, equilibrium or steady state is attained more slowly. At low temperatures, the fluid exhibits a solid-like structure, whereas at high temperatures, a liquid-like structure forms as the fluid’s viscosity decreases. With the creation of yield stress in the region with high shear rates, shear stress increases with temperature, and yield stress increases with temperature. The viscoelastic system is underdamped, and the amount of fluid deflected at 25 ◦C is small, which prevents the disruption of the fluid’s rheology. This develops as a result of the presence of a small deflection angle, which facilitates the development of high magnetoviscosity at low temperature. High viscous effect forms at low temperatures due to the creation of low shear stress and low deflection angle at temperature 25 ◦C. The sample has a single phase and FCC structure, which X-ray diffraction research has verified.

A trivalent ferrite ferrofluid compound’s rheological response to angular frequency, magnetic induction and shear induction of chain clusters

At low and high temperatures in the presence and absence of magnetic fields, the effects of shear rate, angular frequency, and shear strain on the rheological characteristics of zinc ferrite ferrofluid is investigated. Chemical co-precipitation was used to create a zinc ferrite ferrofluid that was then coated with oleic acid to improve the stability of the fluid’s particles and avoid particle agglomeration. We looked at the rheological characteristics caused by the induced magnetic field, such as the shear stress, complex viscosity, storage modulus, loss modulus, relaxation modulus, viscous torque, damping factor, and figure of merit. From the analysis of time dependent relaxation modulus, a steady-state rheological system is formed at time interval beyond 50 s. As the shear and complex viscosities increase with an increase in magnetic field and a decrease in temperature, obstruction to fluid flow is produced. When a rheological system operates at low angular frequency and high shear rate, high shear stress is loaded; when it operates at high angular frequency and low shear rate, low shear stress is loaded. In the absence of magnetic field, a low viscosity 0.425 Pa.s and shear force 46 Pa were formed, while high viscosity 8.140 Pas and shear stress 168 Pa were formed when magnetic field 1.000 Tesla was applied. The oscillatory mode test demonstrates a change in structure from solid to liquid due to the establishment of a crossover point between shear strain 55 and 64%, supporting the solid–liquid phase transition behavior. The damping analysis demonstrates that the system is in fact excessively dampened, and it may now be utilized to reduce vibrations in a system. The system is really overdamped showing a maximum damping factor 2.08, according to the damping study, and can therefore be used to reduce vibrations in other systems. The fluid exhibits non-Newtonian shear-thinning behavior as shear rates increase. A high viscous torque is created at low shear strain and high angular frequency, which leads to the creation of a strong rotating magnetic field.

The effect of ions doping on the rheological properties of ferrite ferrofluids

A series of ferrite nanoparticles were synthesized via ion doping and then were coated by surfactant and dispersed in perfluorinated polyether oil (PFPE-oil), and the various ferrite ferrofluids were obtained. The scanning electron microscope was used to characterize the morphology of particles and the dispersed state of ferrofluid, energy-dispersive spectroscopy was used to study the chemical composition of particles, fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis were used to study the coated effect of PFPE-acids on particles, vibrating sample magnetometer was used to research the magnetization curves of ferrite particles, and the rheological property of the ferrite ferrofluids was studied by a rheometer. The results show that Zn2+, Mn2+/Zn2+, and Dy3+ ions were doped in the ferrite nanoparticles with a size less than 50 nm. The four kinds of ferrite nanoparticles have the characteristics of super-paramagnetic materials, and the M-T curves decrease with increasing temperature, while their decline rates are notably different. The ferrite particles are coated with PFPE acids chemically, and the ferrofluids have well dispersion stability. The rheological properties of the ferrite ferrofluids change with the variation of ion doping, magnetic field strength, temperature, etc. The magnetism and viscosity of ferrite ferrofluids are regularly affected by ion doping, and the results will have a great significance on basic research and related applications.

Morphological Effects on Natural Convection Heat Transfer of Magnesium Ferrite Ferrofluid

This investigation intends to analyze the influence of nanoparticles morphology on the magnetic flux dependent thermo-physical properties and magnetohydrodynamic free convection heat transfer performance of water-based magnesium ferrite ferrofluid under various volume fractions. The thermo-physical parameters of the ferrofluid suspended with cube shaped particles are examined at 25 °C using KD2 pro thermal analyzer, Ostwald viscometer and specific gravity bottle under magnetic flux. The free convection heat transfer is obtained using heat pipes assisted cubical enclosure. Without the influence of magnetic flux, the thermal conductivity of the ferrofluid was improved by a maximum of 12.75% at a volume fraction of 0.15%. At the same time, the maximum viscosity and density were raised by 32.92% and 6.11% at a volume fraction of 0.20% in comparison with water. Under the influence of 350 Gauss, thermal conductivity, and viscosity of ferrofluid enhanced by 21.81% and 37.41% while the density decreased by 4.91%. It was revealed that the addition of cube-shaped magnesium ferrite particles in ferrofluid improved the thermo-physical properties. The optimum concentration for maximum heat transfer is reduced to 0.025% with the use of cube shaped particles compared to other types of nanoparticles reported in previous studies.

Manyetik Alan Altinda Nanoakişkanlarin Akiş Karakteristiklerinin İncelenmesi

The existence/application of an externally induced magnetic field, like in satellite cooling applications, causes a decrement in heat transfer when used with nanofluids. This study investigates the flow characteristics and velocity profile of distilled water, alumina nanofluid, and cobalt ferrite ferrofluid in a horizontal cylindrical heat pipe flowing in a laminar regime and being exposed to an external magnetic field. All of the simulations were performed with ANSYS Fluent MHD module, for a concentration of 2%, Reynolds number of 10, and Hartmann numbers of 25, 50, and 150. The velocity profiles, pressure drops, and flow characteristics are examined by varying the magnetic field intensity while keeping all other parameters constant. It is concluded that an external magnetic field causes a deterioration in the velocity profiles of the nanofluid, especially in cobalt ferrite, while it does not have a significant effect on water. When the magnitude of the magnetic field is increased by 2 times, it is seen that the velocity of the fluid decreases by 6% and increasing the magnetic field from 0 to 50 Tesla causes a deceleration rate of 9%, which leads to the conclusion that application of a magnetic field for the first time has a more significant slowing effect when comparing it to increasing the magnetic field. In addition, when a magnetic field of 50 Tesla is considered, the maximum velocity of alumina is lower than that of water by 5.10%, and the maximum velocity of cobalt ferrite is lower by 28.57%.

Rheological investigation of strain rate and magnetic field on the magnetorheology of zinc ferrite ferrofluid

Rheological investigation of strain rate and magnetic field on the magnetorheology of zinc ferrite ferrofluid

Fabrication and characterization of superparamagnetic nickel ferrite ferrofluid

Because of their unique magnetic characteristics, magnetic nanoparticles are being used in various applications. We used a two-step method to create nickel ferrite ferrofluid in this study. The first step included hydrothermal preparation of oleic acid-capped nickel ferrite nanoparticles, followed by surface functionalization of the particles with citric acid, which made the nanoparticles hydrophilic. The materials' phase purity, functional groups, and magnetic behaviour were investigated. The production of mono-dispersed spherical nanoparticles with an average diameter of 9 ± 3.6 nm was shown by TEM images. With a blocking temperature of 53 K, ZFC-FC measurements verified the sample's superparamagnetic properties. The average magnetic moment per particle and the average size of the magnetic particle were calculated using the Langevin function.

Influence of temperature and magnetic field on rheological behavior of ultra-sonicated and oleic acid coated cobalt ferrite ferrofluid

The research work examines the influence of magnetic field and temperature on the magneto viscous and magneto viscoelastic nature of cobalt ferrite ferrofluid (FF). Steady rotational and oscillatory rheological measurements which examined the rheological responses of the fluid have been performed. A steady state flow was established through the application of suitable relaxation modulus and attempt was made to regulate unwanted oscillatory behavior by application of damping function. The particles were ultra-sonicated and coated with oleic acid to minimize agglomeration and improve fluid stability and its rheological behavior. The fluid is underdamped at high shear rate and high magnetic field due to damping factor that is less than one but overdamped behavior was obtained at low shear rate. Storage modulus (G’) and loss modulus were used to examine the viscoelastic behavior of the fluid. This fluid is accurately viscoelastic, because it exhibits of both elastic and viscous behaviors. Storage modulus is higher than loss modulus as a result of dominant magnetostatic forces at low strain rate. A crossover point was formed at critical strain due to overlapping of loss and storage modulus curves at high strain rate, this effect indicates the formation of phase transition. This occurred due to dominant hydrodynamic forces over magnetostatic forces. Magnetic effect revealed a steady increase in viscous effect which is as a result of formation of enhanced chain-like structure and strong particle aggregation. Enhanced viscous effect was shown in the presence of low temperature, low angular frequency and high applied magnetic field.

Effect of surfactant mediated inter-particle interactions on the magnetic properties of Manganese Zinc Ferrite ferrofluid

Ferrofluids of spinel ferrites presents a multitude of applications in engineering and biomedical fields. The nature of the divalent ions and their occupancy decides the magnetic properties of the spinel ferrites. The nanoparticles of these ferrites and their suspensions in various liquids are of great fundamental interest as well. This paper reports the synthesis and magnetic relaxation studies on fluid particles of Zinc substituted manganese ferrite. Nanoparticles of manganese zinc ferrite with a particle size around 5 -6 nm, are synthesized by chemical method and suspended in kerosene and water, with proper surfactants. The structural characterization is carried out by x-ray diffraction and electron microscopy. The magnetic properties are studied by employing a SQUID magnetometer. The temperature dependent static magnetic measurements and analysis reveal the inter particle interaction effects on the overall magnetic behavior of the constituent magnetic nanoparticles. The modification of the magnetic relaxation based on the surfactant is analysed.

Light-Transmitting Measurements through Starch-Coated Cobalt Ferrite Ferrofluids Exposed to an External Magnetic Field

The light-transmitting measurements at the 655 nm wavelength have been performed through starch-coated cobalt ferrite ferrofluids synthesized by well-established synthetic methods, i.e., coprecipitation, mechanochemical, ultrasonically assisted coprecipitation, microemulsion, and microwave-assisted hydrothermal syntheses, exposed to an external magnetic field of 200–400 mT. The investigated samples can be divided into the two groups. The first is where the samples showed higher rate of agglomeration and sedimentation effects. The group of samples synthesized by microemulsion, microwave-assisted hydrothermal method, and mechanochemical method showed less pronounced rate of chain formation. Such measurements present good method for the preliminary selection of possible magnetic resonance imaging (MRI) contrast agents between differently synthesized ferrite suspensions.

Effect of magnetic field on the thermophysical properties of low-density ferrofluid with disk-shaped MgFe2O4 nanoparticles

In this experimental study, the thermophysical properties of a novel disk-shaped magnesium ferrite / water-based ferrofluids (volume fraction from 0 .01 % to 0.20 %) are measured in terms of its thermal conductivity (k), density (ρ), and viscosity (μ) without and with the application of magnetic field (0−350 Gauss). The hydrothermal method is applied to the synthesis of the Magnesium ferrite (MgFe2O4) nanoparticles. The VSM analysis of ferrite particles indicates a soft ferromagnetic nature. The thermal conductivity of the ferrofluid is measured at 25 °C, while the viscosity and density are measured between 25 and 70 °C. The findings reveal that the thermal conductivity of magnesium ferrite ferrofluid rises by 10.06 % in the absence of the magnetic field and 13.92 % through the attendance of the magnetic field of 350 G at 0.20 % volume fraction. The viscosity of ferrofluid is increased by 28.31 % with the application of a magnetic field at a volume fraction of 0.20 %. The density of the ferrofluid enhances 5.33 % with the highest volume fraction of 0.20 % compared to the base fluid, and it decreases with the application of magnetic field. The experimental properties are validated against the available theoretical models. A new correlation also established for the prediction of thermal conductivity, viscosity, and density of ferrofluid with the application of magnetic field. The estimation of enhancement ratio indicates that the prepared fluid is suitable for heat transfer applications.

Electro-optics Behaviors of Fe3O4 Ferrofluids: A Preliminary Study

In this paper, we report the experimental observation of electro-optics effect in the ferrofluids comprising of Fe3O4 nanoparticles by a 1 mW He-Ne laser beam. An external electric field was applied perpendicular to the beam. Ferrite ferrofluid was prepared by using a coprecipitation-sonochemical technique. The effect of the electric field on the optical properties of ferrofluid was still too weak as we had expected. One possibility that can be suspected as the cause is that the electric field applied to ferrofluid is still too weak.

A Preliminary Study on the Thermo-optics Characteristics of Chromium Ferrite Ferrofluids

In this paper, we report the experimental observation of temperature influence on optical properties of ferrofluids comprising of chromium ferrite nanoparticles by a 1 mW He-Ne laser beam. An external thermal field was maintained perpendicular to the beam. In this research, the thermal response of chromium ferrite ferrofluids prepared by coprecipitation-sonochemical technique was studied. The preliminary investigation showed that the chromium ferrite ferrofluids have an excellent property as a candidate for a temperature sensor application showing a good response on the temperature treatment. Interestingly, we found a hysteresis phenomenon in one cycle in transmission light originating by varying temperature.

Effect of line dipole magnetic field on entropy generation of Mn-Zn ferrite ferrofluid flowing through a minichannel using two-phase mixture model

A numerical investigation is carried out to assess the effect of magnetic field on the entropy generation characteristics of a magnetic nanofluid flowing between parallel plates using the two-phase mixture model. The magnetic field is generated by one or multiple line dipole(s). The influences of Reynolds number, magnetic field strength, number of dipoles and also their arrangement are examined on the thermal, frictional and total entropy generation rates both locally and globally. The application of a magnetic field leads to rotation of magnetic nanofluid and consequently, mixing in the flow and more uniform temperature distribution. The results show that augmenting the magnetic field strength from 0.01 Am to 0.1 Am, at Reynolds number of 500, results in a 2.93% increase and a 5.54% decrease in the global frictional and thermal entropy generation rates, respectively. Moreover, it is reported that increasing the Reynolds number from 500 to 2000, for a magnetic field with strength of 0.1 Am, causes an increase of 63.02% and a decrease of 50.45% in the global frictional and thermal entropy generation rates, respectively. In the case of one dipole, the results reveal that the position of the dipole has no effect on the global total entropy generation rate, but this is not true for two and three dipoles cases.

Sintesis Kromium Ferit Dari Pasir Pantai dan Karakterisasi Awal Sensor Suhu

Ferrofluids for temperature sensor application become one of the important modern technology applications. Therefore, the development of the beach sand-based ferrofluids for temperature sensor becomes new and essential things for cutting off their production. In this research, the preliminary investigation of the temperature sensor is developed based on the chromium ferrite ferrofluids. The sample in powder and fluid were prepared by coprecipitation-sonochemical technique. The powder sample which was characterized by XRD has the crystallite size of 10 nm with high purity. The preliminary investigation shows that the chromium ferrite ferrofluid has a good property as a candidate for temperature sensor application showing a good response on the temperature treatment DOI: http://dx.doi.org/10.17977/um024v3i12018p001

Magnetoviscosity of Paraffin-Based Barium Ferrite Ferrofluid

The ferrofluids synthesized from platelet magnets in liquid media are quite interesting due to their shape-induced magnetic response. In this paper, the magnetoviscosity of barium ferrite (BaM) ferrofluid is studied to understand the magnetic response of BaM platelet particles. The platelet particles were synthesized by the hydrothermal method and coated with oleic acid. The X-ray diffraction data confirm the platelets consisting of BaM phase. The field-emission scanning electron microscopy and transmission electron microscopy micrographs show hexagonal platelets of 3–5 nm thickness and 50–250 nm in size. The magnetization versus magnetic field plot shows hard ferromagnetic behavior of the nanoparticles. The ferrofluid was synthesized by dispersing coated platelets in paraffin. The flow curves of the ferrofluid exhibit shear thinning with power law behavior in the presence of magnetic field. The yield stress values are determined by extrapolating shear stress versus shear rate plots to zero shear rate at various applied magnetic field values using Herschel–Bulkley equation. The magnetoviscosity, $\eta $ , of the ferrofluid as a function of magnetic field is investigated at various shear rates. The $\eta $ value increases with the increase in magnetic field, reaches a maximum value and then saturates at higher fields. This trend is due to the alignment of platelet-shaped magnetic particles along the direction of magnetic field at different shear rates. With the increase in magnetic field, the interaction between the magnetic nanoparticles and their arrangement becomes stronger leading to stacked plate chain formation. This shows that the variation of magnetoviscosity as a function of shear rate can be controlled by competition between the flow field and the magnetic field.

Formation of Columnar Structures by the Magnetically Directed Assembly of Cobalt Ferrite Nanoparticles

We have studied the assembly of cobalt ferrite nanoparticles in a magnetic field. Nanoparticles of different sizes, i.e., 5-40 nm, were synthesized with coprecipitation or under hydrothermal conditions. Their saturation magnetization values ranged between 31 and 68 Am2 /kg, respectively, resulting in a strong magnetic attraction and agglomeration between the nanoparticles. In aqueous ferrofluids this was prevented by the adsorption of citric acid on the nanoparticles' surfaces. The estimated interaction energies show that the DLVO (Derjaguin, Landau, Verwey, Overbeek) theory fails to explain the stability of cobalt ferrite ferrofluids and that the solvation interaction cannot be neglected. Cobalt ferrite ferrofluids were deposited on alumina substrates and dried in a magnetic field of 0.03 or 0.5 T. The homogeneity of the deposits decreased with the increasing saturation magnetization of the nanoparticles and/or with the increasing magnetic field, until columnar structures were formed from the nanoparticles with Ms ≥ 55 Am2/kg under a magnetic field of B = 0.5 T.