scholarly journals Heat dissipation in Sm3+ and Zn2+ co-substituted magnetite (Zn0.1SmxFe2.9-xO4) nanoparticles coated with citric acid and pluronic F127 for hyperthermia application

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
S. Shatooti ◽  
M. Mozaffari ◽  
G. Reiter ◽  
D. Zahn ◽  
S. Dutz
Keyword(s):  
Citric Acid ◽  
Heat Dissipation ◽  
Magnetic Measurements ◽  
Exchange Interactions ◽  
Pluronic F127 ◽  
Precipitation Method ◽  
Solution Ph ◽  
Coated Nanoparticles ◽  
Phase Spinel ◽  
Co Precipitation

AbstractIn this work, Sm3+ and Zn2+ co-substituted magnetite Zn0.1SmxFe2.9-xO4 (x = 0.0, 0.01, 0.02, 0.03, 0.04 and 0.05) nanoparticles, have been prepared via co-precipitation method and were electrostatically and sterically stabilized by citric acid and pluronic F127 coatings. The coated nanoparticles were well dispersed in an aqueous solution (pH 5.5). Magnetic and structural properties of the nanoparticles and their ferrofluids were studied by different methods. XRD studies illustrated that all as-prepared nanoparticles have a single phase spinel structure, with lattice constants affected by samarium cations substitution. The temperature dependence of the magnetization showed that Curie temperatures of the uncoated samples monotonically increased from 430 to 480 °C as Sm3+ content increased, due to increase in A-B super-exchange interactions. Room temperature magnetic measurements exhibited a decrease in saturation magnetization of the uncoated samples from 98.8 to 71.9 emu/g as the Sm3+ content increased, which is attributed to substitution of Sm3+ (1.5 µB) ions for Fe3+ (5 µB) ones in B sublattices. FTIR spectra confirmed that Sm3+ substituted Zn0.1SmxFe2.9-xO4 nanoparticles were coated with both citric acid and pluronic F127 properly. The mean particle size of the coated nanoparticles was 40 nm. Calorimetric measurements showed that the maximum SLP and ILP values obtained for Sm3+ substituted nanoparticles were 259 W/g and 3.49 nHm2/kg (1.08 mg/ml, measured at f = 290 kHz and H = 16kA/m), respectively, that are related to the sample with x = 0.01. Magnetic measurements revealed coercivity, which indicated that hysteresis loss may represent a substantial portion in heat generation. Our results show that these ferrofluids are potential candidates for magnetic hyperthermia applications.

scholarly journals Magnetically recyclable Ag/TiO2 co-decorated magnetic silica composite for photodegradation of dibutyl phthalate with fluorescent lamps

2020 ◽  
Vol 81 (4) ◽  
pp. 790-800
Author(s):  
Zhiqiang Ding ◽  
Yue Liu ◽  
Yong Fu ◽  
Feng Chen ◽  
Zhangpei Chen ◽  
...  
Keyword(s):  
Magnetic Particles ◽  
Dibutyl Phthalate ◽  
Degradation Process ◽  
Environmental Safety ◽  
Degradation Efficiency ◽  
Precipitation Method ◽  
Solution Ph ◽  
Fluorescent Lamps ◽  
Butyl Phthalate ◽  
Co Precipitation

Abstract In recent years, industrial contaminants and especially organic pollutions have been threatening both environmental safety and human health. Particularly, dibutyl phthalate (DBP) has been considered as one of the major hazardous contaminants due to its widespread production and ecological toxicities. Consequently, reliable methods toward the efficient and environmentally benign degradation of DBP in wastewater would be very desirable. To this end, a novel magnetically separable porous TiO2/Ag composite photocatalyst with magnetic Fe3O4 particles as the core was developed and successfully introduced to the photocatalytic degradation of DBP under visible irradiation with a fluorescent lamp. The presented work describes the grafting of Ag co-doped TiO2 composite on the silica-modified porous Fe3O4 magnetic particles with a simple and inexpensive chemical co-precipitation method. Through the investigation of the influencing factors including photocatalyst dosage, initial concentration of DBP, solution pH, and H2O2 content, we found that the degradation efficiency could reach 74%. The photodegradation recovery experiment showed that the degradation efficiency of this photocatalyst remained almost the same after five times of reuse. In addition, a plausible degradation process was also proposed involving the attack of active hydroxyl radicals generated from this photocatalysis system and production of the corresponding intermediates of butyl phthalate, diethyl phthalate, dipropyl phthalate, methyl benzoate, and benzoic acid.

Preparation of Chitosan - Hydroxyapatite Nanocomposites

2011 ◽  
Vol 284-286 ◽  
pp. 1760-1763
Author(s):  
Jing Xian Zhang ◽  
Dong Liang Jiang ◽  
Qing Ling Lin ◽  
Zhong Ming Chen ◽  
Zheng Ren Huang
Keyword(s):  
Mechanical Properties ◽  
Fourier Transform ◽  
Phase Composition ◽  
Fourier Transform Infrared ◽  
Chitosan Solution ◽  
Precipitation Method ◽  
Solution Ph ◽  
Cylindrical Form ◽  
Infrared Spectrometer ◽  
Co Precipitation

Chitosan/Hydroxyapatite composites with a homogeneous nanostructure have been prepared by a co-precipitation method. Initially, a chitosan solution was prepared and mixed with the (NH4)2HPO4 solution. After homogenizing, the obtained chitosan/ (NH4)2HPO4 solution was gradually dropped into the Ca (NO3)2.4H2O solution under stirring. The solution pH was adjusted to 9 using NH3.H2O. The precipitate was compressed into a cylindrical form followed by post treatment. The microstructure, phase composition and mechanical properties of the resulting chitosan-HAp composites were characterized. In the presence of chitosan, HAp crystallites were found to be well aligned along the c-axes in the respective aggregates. Fourier transform infrared spectrometer results indicated that an intermolecular bridging complexes might have been developed between the chitosan and HAp. The compact composites obtained were mechanically flexible, the highest strength was found to be 38.4 MPa for chitosan/HAp samples with a 20 wt% of chitosan.

PROCESSING OF NANO-CRYSTALLITE SPINEL FERRITE PREPARED BY CO-PRECIPITATION METHOD

2009 ◽  
Vol 23 (03) ◽  
pp. 365-374 ◽  
Author(s):  
P. MATHUR ◽  
A. THAKUR ◽  
M. SINGH
Keyword(s):  
Grain Size ◽  
Curie Temperature ◽  
Spinel Ferrite ◽  
Initial Permeability ◽  
Nano Particles ◽  
Precipitation Method ◽  
Ferrite Powder ◽  
Type Semiconductor ◽  
Phase Spinel ◽  
Co Precipitation

Mn 0.4 Cu 0.4 Zn 0.2 Fe ferrite was synthesized by soft chemical approach called co-precipitation technique. The ferrite powder was calcined, compacted and sintered at 700°C and 800°C for 3 h. The initial permeability, density, grain size, Curie temperature and dc resistivity have been studied. X-ray diffraction (XRD) method confirmed the sample to be a single-phase spinel structure without unreacted constituents. The particle size was calculated from XRD spectrum using Scherrer's formula and found to be ~55 nm. Then, nanoparticles were observed with tunneling electron microscopy (TEM). Further, scanning electron micrograph (SEM) also confirmed nano-phase and the uniformity of the particles. The initial permeability values do not exhibit much variation with temperature, except near Curie temperature, where it falls sharply. The initial permeability is found to increase with the increase in sintering temperature. This is attributed to the increase in the grain size. Calculation of activation energy indicates that the given ferrite is p-type semiconductor. Mössbauer study of these samples shows superparamagnetic behavior, which also confirms the formation of nano-particles. Possible models and mechanisms contributing to these processes have been discussed.

scholarly journals ON SPIN HAMILTONIAN FITS TO MÖSSBAUER SPECTRA OF NiFe2O4 NANOPARTICLES SYNTHESIZED BY CO-PRECIPITATION

2020 ◽  
Vol 5 (6) ◽  
Author(s):  
Jose Higino Dias Filho ◽  
Jorge Luis López Aguilar ◽  
Adriana Silva De Albuquerque ◽  
Renato Dourado Maia ◽  
Wesley De Oliveira Barbosa ◽  
...  
Keyword(s):  
Mössbauer Spectra ◽  
Magnetic Measurements ◽  
Magnetic Transition ◽  
Particle Diameter ◽  
Evolutionary Strategies ◽  
Precipitation Method ◽  
Magnetic Anisotropy Energy ◽  
Magnetic Transition Temperature ◽  
Mossbauer Spectra ◽  
Co Precipitation

Nanocrystalline NiFe2O4 particles prepared by chemical co-precipitation method were studied using magnetic measurements, 57Fe Mössbauer spectroscopy, X-ray diffraction, and transmission electron microscopy. Fits to Mössbauer spectra, in the range of 4.2 K – 300 K, were done using spin hamiltonians to describe both the electronic and nuclear interactions, a model of superparamagnetic relaxation of two levels (spin ½) and stochastic theory, a log-normal particle size distribution function as well as a dependency of the magnetic transition temperature and the anisotropy constant on particle diameter. We have used evolutionary strategies to fit the more complex Mössbauer spectra line shapes. The nanoparticles have an average size of 7 nm and exhibit superparamagnetism at room temperature. The saturation magnetization (Ms) at 4.2 K was determined from M vs. 1/H plots by extrapolating the value of magnetizations to infinite fields, to 24.21 emu/g and coercivity to 3.15 kOe. A magnetic anisotropy energy constant (K) 1.9´105 J/m3, at 4.2 K, were calculated from magnetization measurements. The synthesis, characterization, and functionalization of magnetic nanoparticles is a highly active area of current research located at the interface between materials science, biotechnology, and medicine. Superparamagnetic iron oxides nanoparticles have unique physical properties and have emerged as a new class of diagnostic probes for multimodal tracking and as contrast agents for magnetic resonance imaging (MRI).

scholarly journals Influence of the sintering temperature on the morphology and structural properties of Ni-Mg substituted of cobalt ferrites

2015 ◽  
Vol 11 (2) ◽  
Author(s):  
R. M. Rosnan ◽  
Zulkafli Othman ◽  
A. A. Ati
Keyword(s):  
Structural Properties ◽  
Spinel Ferrite ◽  
Precipitation Method ◽  
Nominal Composition ◽  
Average Crystalline Size ◽  
X Ray Diffraction ◽  
Cobalt Ferrites ◽  
Phase Spinel ◽  
Co Precipitation ◽  
Good Agreement

This study evaluates the morphology and structural properties of Ni-Mg substituted Cobalt ferrite samples prepared through the co-precipitation method. The nominal composition of Co0.5Ni0.5−xMgx Fe2O4 in the range x = 0.1 have been synthesized and then were sintered at temperature 700 and 1000°C for 10 hour with a heating rate of 5°C/min. The prepared nano-ferrites were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM). XRD confirmed formation of single phase spinel ferrite with average crystalline size in the range of 40–120 nm. Further information about the structure and morphology of the nanoferrites was obtained from FESEM and results are in good agreement with XRD.

Study on Nanometer ATO Powder Prepared with Citric Acid as Dispersant and its Conductive Properties

2014 ◽  
Vol 599-601 ◽  
pp. 118-123
Author(s):  
Xie Bin Zhu ◽  
Jing Chen ◽  
Zhong Jia Huang
Keyword(s):  
Citric Acid ◽  
Ph Value ◽  
Ammonia Solution ◽  
Raw Material ◽  
Precipitation Method ◽  
Technological Condition ◽  
Nano Powder ◽  
Sb Doping ◽  
Co Precipitation ◽  
Conductive Properties

Antimony doped tin oxide (ATO) Nano powder was prepared by co-precipitation method, selecting SnCl4 • 5H2O and SbCl3 as the main raw material, citric acid as dispersant, ammonia solution (1:3) as precipitant, which was characterized, analyzed and tested by XRD, SEM, and digital conductivity meter. The optimum technological condition is that evenly-scattered powder whose crystalline structure is rutile, particle is sphere, size is about 10nm and conductivity is 1.32 ×102 µs/cm can be obtained when the reaction temperature is 60°C, Sb doping ratio is 10%, pH value is 2, calcinations temperature are 600°C and calcinations time are 2 hours.

Microstructural and Magnetic Studies on Calcined Ni-Zn Ferrite Powders Prepared by Chemical Co-Precipitation Method

2011 ◽  
Vol 264-265 ◽  
pp. 524-529
Author(s):  
I.Z. Rahman ◽  
T.T. Ahmed
Keyword(s):  
Room Temperature ◽  
Magnetic Measurements ◽  
Precipitation Method ◽  
Particle Sizes ◽  
Magnetic Studies ◽  
Zn Ferrite ◽  
Different Temperatures ◽  
Bet Technique ◽  
Co Precipitation ◽  
Cation Distributions

In this paper, we report on structural and magnetic properties of NiZn ferrite powders prepared by chemical co-precipitation method and calcined at different temperatures. Structural, topological and compositional analyses were performed by XRD, SEM, AFM and EDX techniques. The cation distributions in Ni0.8Zn0.2Fe2O4 ferrites were investigated by XPS (Al K radiation: h=1486.6 eV). Particle sizes were measured using AFM techniques and results were compared with BET technique and magnetic measurements were carried out using a vibrating sample magnetometer at room temperature.

scholarly journals Immobilization of Chitosanases onto Magnetic Nanoparticles to Enhance Enzyme Performance

Catalysts ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 401 ◽  
Author(s):  
Wei Wang ◽  
Na Guo ◽  
Wencan Huang ◽  
Zhaohui Zhang ◽  
Xiangzhao Mao
Keyword(s):  
Magnetic Measurements ◽  
Sol Gel ◽  
Residual Activity ◽  
Precipitation Method ◽  
Optimal Conditions ◽  
Initial Activity ◽  
Transmission Electron ◽  
Infrared Spectrometer ◽  
Ft Ir ◽  
Co Precipitation

In this study, chitosanase cloning from Streptomyces albolongus was fermented and purified by a Ni-NTA column. Fe3O4-SiO2 magnetite nanoparticles (MNPs) were synthesized by the co-precipitation method coating with silica via a sol-gel reaction and were then amino functioned by treating with 3-aminopropyltriethoxysilane. Chitosanases were immobilized onto the surface of MNPs by covalent bonding (MNPs@chitosanase). Transmission electron microscopy (TEM), Fourier transform infrared spectrometer (FT–IR), and magnetic measurements were used to illustrate the MNPs and immobilized chitosanase. The optimal conditions of immobilization were studied. The thermal, pH, and stabilities of immobilized chitosanase were tested and the results showed that the stabilities were significantly enhanced compared with free chitosanase. After being recycled 10 times, the residual activity of the immobilized chitosanase was 43.7% of the initial activity.

scholarly journals Room Temperature Magnetic Memory Effect in Cluster-Glassy Fe-Doped NiO Nanoparticles

Nanomaterials ◽  
2020 ◽  
Vol 10 (7) ◽  
pp. 1318 ◽  
Author(s):  
Ashish Chhaganlal Gandhi ◽  
Tai-Yue Li ◽  
B. Vijaya Kumar ◽  
P. Muralidhar Reddy ◽  
Jen-Chih Peng ◽  
...  
Keyword(s):  
Magnetic Moment ◽  
Room Temperature ◽  
Magnetic Measurements ◽  
Oxide System ◽  
Precipitation Method ◽  
Magnetic Memory ◽  
Nio Nanoparticles ◽  
Magnetic Anisotropy Energy ◽  
Spintronic Devices ◽  
Co Precipitation

The Fe-doped NiO nanoparticles that were synthesized using a co-precipitation method are characterized by enhanced room-temperature ferromagnetic property evident from magnetic measurements. Neutron powder diffraction experiments suggested an increment of the magnetic moment of 3d ions in the nanoparticles as a function of Fe-concentration. The temperature, time, and field-dependent magnetization measurements show that the effect of Fe-doping in NiO has enhanced the intraparticle interactions due to formed defect clusters. The intraparticle interactions are proposed to bring additional magnetic anisotropy energy barriers that affect the overall magnetic moment relaxation process and emerging as room temperature magnetic memory. The outcome of this study is attractive for the future development of the room temperature ferromagnetic oxide system to facilitate the integration of spintronic devices and understanding of their fundamental physics.

Sign in / Sign up

Export Citation Format

Share Document