Non-magnetic Nanoparticles Research Articles

Effect of temperature on memory effect in nematic phase of liquid crystal and their composites with aerosil and geothite nanoparticles

Liquid crystal doped with aerosil nanoparticles is known for exhibiting an electromechanical memory effect. After exposing the composite to the electric field the state induced by the electric field stays remembered due to the presence of aerosil nanoparticles. In this paper, we investigated the memory effect induced by electric and magnetic fields. Liquid crystal 4-cyano-4′-pentylbiphenyl doped with non-magnetic aerosil nanoparticles and a mixture of aerosil nanoparticles and elongated magnetic goethite nanoparticles were explored via capacitance measurements. Studied systems exhibited hysteresis in capacitance-voltage and capacitance-magnetic field dependences. The measurements revealed a great impact of temperature and heating/cooling rate on the hysteresis of the system. Observed electromechanical and magnetomechanical memory effect provides potential use of the system as voltage-driven or magnetic field-driven non-volatile memory devices.

Natural convection of hybrid nanofluid with magnetic and thermal effects over an inclined needle

Hybrid nanofluids have several potential applications in various industries, including electronics cooling, automotive cooling systems, aerospace engineering, and biomedical applications. The primary goal of the study is to provide more information about the characteristics of a steady and incompressible stream of a hybrid nanofluid flowing over a thin, inclined needle. This fluid consists of two types of nanoparticles: non-magnetic nanoparticles (aluminium oxide) and magnetic nanoparticles (ferrous oxide). The base fluid for this nanofluid is a mixture of water and ethylene glycol in a 50:50 ratio. The effects of inclined magnetic fields and joule heating on the hybrid nanofluid flow are considered. The Runge-Kutta fourth-order method is used to numerically solve the partial differential equations and governing equations, which are then converted into ordinary differential equations using similarity transformations. Natural convection refers to the fluid flow that arises due to buoyancy forces caused by temperature differences in a fluid. In the context of an inclined needle, the shape and orientation of the needle have significantly affected the flow patterns and heat transfer characteristics of the nanofluid. These analyses protest that raising the magnetic parameter results in an increase in the hybrid nanofluid thermal profile under slip circumstances. Utilizing the potential of hybrid nanofluids in a variety of technical applications, such as energy systems, biomedicine, and thermal management, requires an understanding of and ability to manipulate these effects.

Dynamic tuning of phase change interfacial thermal energy transport in hybrid nano-enhanced phase change materials by a non-uniform magnetic field

The present study aims to explore the synergistic enhanced phase change heat transfer behavior between magnetic field and hybrid nanoparticles under the consideration of non-Newtonian effects. The visualized experiments are conducted using thermochromic liquid crystal technology to extract the interconnection between dynamic phase change interface evolution and temperature change of hybrid nano-enhanced phase change material (HNEPCM), and thermocouples to measure temperature data inside the latent heat thermal energy storage unit. The magnetic field and hybrid nanoparticles synergistic mechanism is then further revealed based on the analysis of liquid phase fraction, Nusselt number, energy storage and energy storage efficiency. The results show that under magnetic field, the magnetic nanoparticles form a “thermal conductivity layer” at the solid-liquid interface, while the non-magnetic nanoparticles in the liquid phase region drive the phase change heat transfer to proceed. The non-Newtonian effect induced by high concentration of HNEPCM can weaken the convection intensity. The competition between natural convection and magnetic viscous effect under magnetic field is induced at different hybrid ratios of magnetic and non-magnetic nanoparticles. High hybrid ratios (R = 1.0, 1.5 and 2.0) will be more favorable to satisfy the high thermal conductivity requirement in the liquid phase region and the dynamic adjustment condition at the phase change interface. Under a non-uniform magnetic field, 1 wt.% HNEPCM with R = 1.0 is considered as the optimum strategy with better energy storage performance and higher magnetic field effect.

(n, m) Distribution of Single-Walled Carbon Nanotubes Grown from a Non-Magnetic Palladium Catalyst

Non-magnetic metal nanoparticles have been previously applied for the growth of single-walled carbon nanotubes (SWNTs). However, the activation mechanisms of non-magnetic metal catalysts and chirality distribution of synthesized SWNTs remain unclear. In this work, the activation mechanisms of non-magnetic metal palladium (Pd) particles supported by the magnesia carrier and thermodynamic stabilities of nucleated SWNTs with different (n, m) are evaluated by theoretical simulations. The electronic metal-support interaction between Pd and magnesia upshifts the d-band center of Pd, which promotes the chemisorption and dissociation of carbon precursor molecules on the Pd surface, making the activation of magnesia-supported non-magnetic Pd catalysts for SWNT growth possible. To verify the theoretical results, a porous magnesia supported Pd catalyst is developed for the bulk synthesis of SWNTs by chemical vapor deposition. The chirality distribution of Pd-grown SWNTs is understood by operating both Pd-SWNT interfacial formation energy and SWNT growth kinetics. This work not only helps to gain new insights into the activation of catalysts for growing SWNTs, but also extends the use of non-magnetic metal catalysts for bulk synthesis of SWNTs.

Valorization of agriculture wastes as biosorbents for adsorption of emerging pollutants: Modification, remediation and industry application

The scarcity of clean water resources combined with other environmental and anthropogenic effects have urged the development of advanced technology for wastewater treatment. Adsorption attracts great attention as a cost-effective technique for the remediation of contaminated water. Despite a broad variety of adsorbents existing in the literature, agriculture waste-derived biosorbents appear to hold the greatest promise for the adsorption of emerging contaminants. Herein, this review introduces the recent developments of biosorbents in the adsorption field. The role of biosorbents in the green chemistry principle and their contribution towards Sustainable Development Goals (SDGs) are discussed. Different types of modifications of biosorbents including activation and modification of magnetic, non-magnetic nanoparticles and polymers are systematically reviewed. Besides, the application of modified biosorbents in the adsorption of heavy metals, dyes, PAHs and oils along with their respective mechanisms are analyzed. Apart from this, the potential practical application of biosorbents is canvassed through introducing simultaneous adsorption of pollutants, usage of real industrial wastewater matrix and reusability performance. Finally, the recommendations for future adsorption studies are presented. This review is anticipated to critically review and explore the potential of biosorbents as economical and green candidates for the adsorption of emerging pollutants.

Analysis of magnetic and non-magnetic nanoparticles with Newtonian/non-Newtonian base fluids over a nonlinear stretching sheet

An unsteady mixed convectional boundary layer flow of a Casson nanofluid having magnetic ( Fe3 O4) and non-magnetic ( Al2 O3) nanoparticles suspension within two different types of base fluids, water (Newtonian) and sodium alginate (non-Newtonian), which incorporates viscous dissipation effects over a nonlinear stretching sheet with magnetic field effects. Some suitable non-dimensional similarity transformations are applied to convert the governing coupled nonlinear partial differential equations into a set of ordinary differential equations and then solved by using differential transformation method in association with Pade-approximation. A comparison has been made with already published results to assure the validity and reliability of the computational results, good agreement is found between the current and previous studies. The impacts of different physical parameters active on flow, temperature, and nanoparticle concentration have been discussed both numerically and graphically. The impact of radiation, internal heat sink/source, viscous, and ohmic dissipation was discussed for magnetic and non-magnetic nanofluid categories. We have also presented the tabular results of various emerging parameters to discuss the nature of skin friction, Nusselt, and Sherwood numbers. It was observed that performance of non-Newtonian (sodium alginate) fluid in heat and mass transfer is slightly better than Newtonian (water) based fluid but no major difference was seen in heat and mass transfer when comparison was made with magnetic and non-magnetic nanoparticles.

The effect of microparticles/nanoparticles surface modification on the magnetorheological fluid properties: A review

Magnetorheological fluids are considered smart materials since their properties change significantly when exposed to a magnetic field, making them interesting for a variety of industries. These fluids are composed of three main components: dispersed particles, carrier fluid, and additives. The latter of which has been the subject of various studies. Therefore, this paper reviews the characteristics and parameters of the particles dispersed in additives and their impact on fluid rheological properties and stability. Also, the surface modification of magnetic and non-magnetic micro and nanoparticles have been investigated. A detailed review of previous studies has been carried out to examine the effects of various parameters such as types of coatings, coating layers, coating thickness, density change, and change in magnetic saturation, on the stability and rheological properties of MR fluids.

A strategy to improve dielectric permittivity of Mg–Zn ferrite by using silver nanoparticles

In this work, we used silver nanoparticles (Ag NPs) to enhance the dielectric properties of magnesium-zinc ferrite (Mg–ZnFe2O4) by enhancing local electric field with the creation of nano/micro capacitors between conducting metal particles (Ag NPs) and insulating host (Mg–ZnFe2O4). Mg–ZnFe2O4 was synthesized using the sol-gel method and silver NPs were decorated on magnesium zinc ferrite (Ag@Mg–ZnFe2O4) by employing a sonication approach. The effect of Ag NPs concentration was studied on the structural, morphological, optical, dielectric, and magnetic properties of Ag@Mg–ZnFe2O4 nanocomposite. X-ray diffraction (XRD) confirmed the presence of cubic Mg–ZnFe2O4 and face-centred cubic (FCC) Ag NPs in Ag@Mg–ZnFe2O4 nanocomposite. The structural parameters such as lattice strain, crystallite size and microstrain were correlated with Ag NPs concentration. The morphological study of Ag@Mg–ZnFe2O4 showed uniform decoration of silver at low concentrations; higher concentrations of silver led to reduced covering due to the agglomeration tendency of Ag NPs. Diffused reflectance spectroscopy (DRS) was employed to estimate the effect of Ag NPs on the optical bandgap of Mg–ZnFe2O4. The bandgap narrowing was observed due to the overlapping of the Ag conduction band with the valence band of Mg–ZnFe2O4. All Ag@Mg–ZnFe2O4 samples showed superparamagnetic behaviour and the saturation magnetization was decreased with the increase in the non-magnetic Ag nanoparticles in the nanocomposite. Impedance spectroscopy (IS) was employed to comprehensively analyze the dielectric properties of Ag@Mg–ZnFe2O4. Complex impedance plane plots confirmed the involvement of relaxation phenomena related to grains and grain boundaries in the observed dielectric properties. The decoration of silver nanoparticles was associated with the realization of a high dielectric constant (∼104) in all prepared samples at low frequency. Moreover, uniform decoration of silver was found to show a more stable dielectric constant with relatively low dielectric loss.

Tailoring the magnetic properties of non-magnetic Cd doped BaTiO3 nanostructures

In order to explore the potential role of non-magnetic cadmium (Cd) in establishing room temperature ferromagnetism (RTFM) in diamagnetic BaTiO3, the analyses of the structural, optical and magnetic properties of non-magnetic ions Cd-doped BaTiO3 nanoparticles of the series Ba1-xCdxTiO3 (x = 0.1 %, 0.3 % and 0.5 %) are successfully accomplished making use of the samples synthesized via facile sol–gel route. The X-ray diffraction and Raman scattering analyses demonstrate that doping with Cd leads to a change in the phase composition of the tetragonal BaTiO3 with the dominance of the BaTi2O5 phase. The core-level XPS study carried out gives direct evidence of cation vacancies due to the richness of lattice oxygen content in the investigated sample at x > 0.1 %. The Cd2+ substitution significantly reduces the optical bandgap of the BaTiO3 nanoparticles from 3.14 to 2.78 eV such that it enhances the PL visible emission. Ferromagnetism originates from the contributions of lattice contractions due to the structural deformation, defect formation and cation vacancies. Among all these samples, 0.3 % Cd doped BaTiO3 leads to the gaining of small saturation magnetization (Ms = 5.40 ± 0.02 × 10-3 emu/g).

Mathematical analysis of electromagnetic scattering by dielectric nanoparticles with high refractive indices

In this work, we are concerned with the mathematical modeling of the electromagnetic (EM) scattering by arbitrarily shaped non-magnetic nanoparticles with high refractive indices. When illuminated by visible light, such particles can exhibit a very strong isotropic magnetic response, resulting from the coupling of the incident wave with the circular displacement currents of the EM fields. The main aim of this work is to mathematically illustrate this phenomenon. We shall first introduce the EM scattering resolvent and the concept of dielectric subwavelength resonances. Then we derive the a priori estimates for the subwavelength resonances and the associated resonant modes. We also show the existence of resonances and obtain their asymptotic expansions in terms of the small particle size and the high contrast parameter. After that, we investigate the enhancement of the scattering amplitude and the cross sections when the resonances occur. In doing so, we develop a novel multipole radiation framework that directly separates the electric and magnetic multipole moments and allows us to clearly see their orders of magnitude and blow-up rates. We prove that at the dielectric subwavelength resonant frequencies, the nanoparticles with high refractive indices behave like the sum of the electric dipole and the resonant magnetic dipole. Some explicit calculations and numerical experiments are also provided to validate our general results and formulas.

Influence of Nanoparticles on Long-Term Thermal Stability of Vegetable Insulating Oil

Although vegetable oil is the best substitute for mineral oil, it exhibits numerous disadvantages, including a high dielectric loss factor, low volume resistivity, and high viscosity. Nanoparticle modification may improve the electrical properties of vegetable oil considerably. In this study, vegetable oil infused with Fe3O4, TiO2, and Al2O3 nanoparticles was investigated. Thermal aging experiments were performed at 100 °C, 130 °C, and 150 °C. The aged vegetable insulating oil was periodically sampled and tested. The results revealed that the nanoparticles with a mass fraction of 0.001% exhibited the best modification effect. The electrical properties of the vegetable insulating oil modified with magnetic nanoparticles were pronounced, whereas the modification effect of nonmagnetic nanoparticles was mild. The general trend of the modification effect of the nanoparticles on vegetable oil became obvious with the increase in the temperature. At the same content, the modification effect of nano-Fe3O4 was superior to that of nano-TiO2 and nano-Al2O3. The results of this study provide experimental and theoretical support for the mechanism of long-term stability of vegetable insulating oil with nanoparticles and can be used to improve the long-term stability of vegetable insulating oil.

The Foam Cell Formation Associated With Imbalanced Cholesterol Homeostasis Due to Airborne Magnetite Nanoparticles Exposure.

Fine particulate matter (PM) is a leading environmental cause for the increased morbidity and mortality of atherosclerosis (AS) worldwide, but little is known about the toxic component and disturbance of PM exposure on foam cell formation, a crucial pathological process in AS. Airborne magnetite nanoparticles (NPs) have been reported to be detected in human serum, which inevitably encounter with macrophages in atherosclerotic plaques, thus throwing potential disturbance on the formation of macrophage-derived foam cells. Here we comprehensively unveiled that the environmental concentrations of PM exposure triggered and potentiated the formation of macrophage-derived foam cells using both real-ambient PM-exposed mice and AS mice models, including high-fat diet-fed mice and apolipoprotein E-deficient mice. The in vitro model further defined the dose-dependent response of PM treatment on foam cell formation. Interestingly, airborne magnetite NPs rather than nonmagnetic NPs at the same concentration were demonstrated to be the key toxic component of PM in the promoted foam cell formation. Furthermore, magnetite NPs exposure led to abnormal cholesterol accumulation in macrophages, which was attributed to the attenuation of cholesterol efflux and enhancement of lipoprotein uptake, but independent of cholesterol esterification. The in-depth data revealed that magnetite NPs accelerated the protein ubiquitination and subsequent degradation of SR-B1, a crucial transporter of cholesterol efflux. Collectively, these findings for the first time identified magnetite NPs as one key toxic component of PM-promoted foam cell formation, and provided new insight of abnormal cholesterol metabolism into the pathogenesis of PM-induced AS.

Shape-Reconfigurable Ferrofluids.

Ferrofluids (FFs) can adapt their shape to a magnetic field. However, they cannot maintain their shape when the magnetic field is removed. Here, with a magneto-responsive and reconfigurable interfacial self-assembly (MRRIS) process, we show that FFs can be structured by a magnetic field and maintain their shape, like solids, after removing the magnetic field. The competing self-assembly of magnetic and nonmagnetic nanoparticles at the liquid interface endow FFs with both reconfigurability and structural stability. By manipulating the external magnetic field, we show that it is possible to "write" and "erase" the shape of the FFs remotely and repeatedly. To gain an in-depth understanding of the effect of MRRIS on the structure of FFs, we systematically study the shape variation of these liquids under both the static and dynamic magnetic fields. Our study provides a simple yet novel way of manipulating FFs and opens opportunities for the fabrication of all-liquid devices.

Ultrasound Study of Magnetic and Non-Magnetic Nanoparticle Agglomeration in High Viscous Media.

Ultrasound attenuation spectroscopy has found wide application in the study of colloidal dispersions such as emulsions or suspensions. The main advantage of this technique is that it can be applied to relatively high concentration systems without sample preparation. In particular, the use of Epstein-Carhart-Allegra-Hawley’s (ECAH) ultrasound scattering theory, along with experimental data of ultrasound velocity or attenuation, provide the method of estimation for the particle or droplet size from nanometers to millimeters. In this study, suspensions of magnetite and silica nanoparticles in high viscous media (i.e., castor oil) were characterized by ultrasound spectroscopy. Both theoretical and experimental results showed a significant difference in ultrasound attenuation coefficients between the suspensions of magnetite and silica nanoparticles. The fitting of theoretical model to experimental ultrasound spectra was used to determine the real size of objects suspended in a high viscous medium that differed from the size distributions provided by electron microscopy imaging. The ultrasound spectroscopy technique demonstrated a greater tendency of magnetic particles toward agglomeration when compared with silica particles whose sizes were obtained from the combination of experimental and theoretical ultrasonic data and were more consistent with the electron microscopy images.

Solid supported ruthenium catalyst for growing single-walled carbon nanotubes with narrow chirality distribution

The past two decades witnessed the thriving of non-conventional nanoparticles in catalytic synthesis of single-walled carbon nanotubes (SWNTs). However, most of the SWNTs are limited to growing on a flat surface which usually suffers low output, thus making the evaluation of SWNT chirality distribution challenging. In this work, we report a solid magnesia (MgO) supported ruthenium (Ru) catalyst for chemical vapor deposition (CVD) growth of SWNTs with sufficient quantity for optical characterizations. Both MgO supported atomically dispersed Ru catalyst and Ru nanoparticles pre-deposited onto porous MgO are active for catalytic synthesis of small diameter SWNTs. Particularly, enriched (6, 5) SWNTs are achieved at temperatures higher than 800 °C by CO CVD, which is partially attributed to the high activity of Ru clusters. Besides, density functional theory (DFT) calculations reveal that the charge transfer from the MgO support to the Ru clusters promotes the carbon precursor absorption and dissociation, accounting for the activation of Ru clusters. This work not only demonstrates the application of atomically dispersed catalyst for CVD growth of SWNTs, but also paves the way for the chirality-selective growth of SWNTs from non-magnetic nanoparticles.

Nanomaterial-immobilized lipases for sustainable recovery of biodiesel – A review

In recent years, the development and deployment of nano-immobilized lipases, as robust biocatalysts, has appeared a promising alternative for biodiesel production. There is a significant hike in using nano-sized support matrices for enzyme-based biotransformation bioprocesses with ever-increasing scientific awareness and nanotechnological advancement. Several nano-scale materials include magnetic and non-magnetic nano-particles, silica nano-particles, carbon nanotubes, graphene/graphene oxide, electrospun nanofibers, metal–organic frameworks, and other nanohybrid matrices are of supreme interest that can shield the catalytic attributes of enzymes after immobilization. Furthermore, nano-sized support matrices immobilized enzymes also offer numerous advantages that native enzymes fail to display on their own, such as high catalytic efficacy, high catalytic turnover, induced stability under harsh reaction conditions, high resistivity against reaction by-products (which otherwise can hinder/inhibit the pristine enzyme), low mass transfer limitation, and high yield under mild processing environment. Lipases are considered principal candidates (biocatalysts) for biodiesel production via transesterification processes, among several industrially relevant enzymes. The nano-immobilized lipases showed a broader working range under different pH and temperature conditions, a highly requisite challenge in indusial settings. Herein, we reviewed several perspectives of sustainable biodiesel production using nano-immobilized lipases. First, following a brief introduction, this review is spotlighting numerous existing and state-of-the-art strategies for lipase immobilization on nanomaterials. Second, the critical factors that characterize nano-biocatalysts are discussed to show the need for optimal reaction conditions to further sustainable transformation. Third, promising nano-carriers to develop lipase-based nanobiocatalyst are given with suitable examples. Fourth, some influential factors that improve the overall performance of nano-immobilized lipases are discussed in terms of the sustainability and processability of the entire production process. Lastly, the contemporary challenges and key considerations for sustained biodiesel production from waste resources are also given for future studies.

Analytical Study on Sodium Alginate Based Hybrid Nanofluid Flow through a Shrinking/Stretching Sheet with Radiation, Heat Source and Inclined Lorentz Force Effects

This study investigated the flow and heat transfer of sodium alginate-based hybrid nanofluids with a stretching/shrinking surface. The heat source/sink, Joule heating, inclined magnetic field, and thermal radiation influences are also examined in the designed model. The mixers of non-magnetic and magnetic nanoparticles are utilized, such as Cu and Fe3O4. The Casson fluid model is applied to determine the viscoplastic characteristics of sodium alginate (SA). The necessary governing SA-based hybrid nanofluid flow equations are solved analytically by hypergeometric function. SA-based hybrid nanofluid velocity, temperature, skin friction, and Nusselt number results are discussed in detail with various pertinent parameters, such as radiation, heat source/sink, inclined angle, magnetic field, Eckert number, and Casson parameters. It is noted that the dimensions of both Cu and Fe3O4 hybrid nanoparticles and Casson parameters are minimized by the momentum surface layer thickness. The magnetic field, radiation, heat source and Casson parameters serve to enhance the thermal boundary layer thickness. Finally, the current result was verified with previously published works.

A Study of Magnetic/Nonmagnetic Nanoparticles Fluid Flow under the Influence of Nonlinear Thermal Radiation

The present research work scrutinizes numerical heat transfer in convective boundary layer flow having characteristics of magnetic ( Fe 3 O 4 ) and nonmagnetic ( Al 2 O 3 ) nanoparticles synthesized into two different kinds of Newtonian (water) and non-Newtonian (sodium alginate) convectional base fluids of casson nanofluid which integrates the captivating effects of nonlinear thermal radiation and magnetic field embedded in a porous medium. The characterization of electrically transmitted viscous incompressible fluid is taken into account within the Casson fluid model. The mathematical formulation of governing partial differential equations (PDEs) with highly nonlinearity is renovated into ordinary differential equations (ODEs) by utilizing the suitable similarity transform that constitutes nondimensional pertinent parameters. The transformed ODEs are tackled numerically by implementing b v p 4 c in MATLAB. A graphical illustration for the purpose of better numerical computations of flow regime is deliberated for the specified parameters corresponding to different profiles (velocity and temperature). To elaborate the behavior of Nusselt and skin friction factor, a tabular demonstration against the distinct specific parameters is analyzed. It is perceived that the velocity gradient of Newtonian fluids is much higher comparatively to non-newtonian fluids. On the contrary, the thermal gradient of non-Newtonian fluid becomes more condensed than that of Newtonian fluids. Graphical demonstration disclosed that the heat transfer analysis in non-Newtonian (sodium alginate)-based fluid is tremendously influenced comparatively to Newtonian (water)-based fluid, and radiation interacts with the highly denser temperature profile of non-Newtonian fluid in contrast to that of Newtonian fluid. Through such comparative analysis of magnetic or nonmagnetic nanoparticles synthesized into distinct base fluids, a considerable enhancement in thermal and heat transfer analysis is quite significant in many expanding engineering and industrial phenomenons.

The therapeutic effects of tumor treating fields on cancer and noncancerous cells

Tumor treating fields (TTFields) are among clinically active anticancer modalities that utilize low‐intensity, intermediate frequency (IF), and alternating electric fields (AEFs) to selectively disrupt mitosis in cancerous cells. Application of TTFields in the range of 100–900 kHz in cancer therapy and its effect on normal and cancer cells have attracted a great deal of interest in recent years. TTFields affect solid tumors by introducing increased chromatid aberrations that reduce the capacity to repair DNA damage and chromosome segregation, resulting in autophagy and subsequent cell death. In this review, we present an overview of the applications of TTFields in the treatment of cancer. We discuss several practical applications of TTField frequencies combined with metallic nanoparticles (NPs) (magnetic or nonmagnetic NPs) for internalization into cancer cells. In addition, TTFields can be combined effectively with chemotherapy and radiotherapy.

Magnetic properties of doped CaF2 powders

Room-temperature “ferromagnetism” found last decades in nonmagnetic nanoparticles is a puzzle that is not solved yet. In this work we report about the observation of room-temperature magnetism in powders of CaF2 doped with CeO2 as well as in the undoped powder but containing small amount impurity. The studied powders were obtained by grinding of bulk crystals using a sapphire mortar with a pestle. Magnetization dependences on magnetic field for the studied powder samples resemble the dependences observed in nonmagnetic oxide nanoparticles like CeO2. The comparative study of bulk and powder fluorite samples unambiguously confirms the key role of surface defects in the observed features. XRD and TEM measurements show that powder samples have particles of different sizes from the micro down to the submicron scale. The undoped bulk fluorite as well as doped with 0.5at.% (two differently grown crystals), 2at.%, 10at.% of CeO2 revealed only diamagnetic or paramagnetic contribution to magnetization curve whereas the powders of the same samples have ferromagnetic-like contribution on M−H curve. This work may help to get new insight in room-temperature “ferromagnetism” phenomenon of nonmagnetic nanoparticles.