scholarly journals Hydrophobically Coated Superparamagnetic Iron Oxides Nanoparticles Incorporated into Polymer-Based Nanocapsules Dispersed in Water

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1219 ◽  
Author(s):  
Elżbieta Gumieniczek-Chłopek ◽  
Joanna Odrobińska ◽  
Tomasz Strączek ◽  
Agnieszka Radziszewska ◽  
Szczepan Zapotoczny ◽  
...  
Keyword(s):  
Aqueous Dispersion ◽  
Average Diameter ◽  
Superparamagnetic Nanoparticles ◽  
X Ray Diffraction ◽  
Bias Effect ◽  
Exchange Bias Effect ◽  
Superparamagnetic Behavior ◽  
Superparamagnetic Iron Oxides ◽  
Organometallic Precursor ◽  
Iron Oxide Magnetic Nanoparticles

This paper reports the characterization of iron oxide magnetic nanoparticles obtained via the thermal decomposition of an organometallic precursor, which were then loaded into nanocapsules prepared via the emulsification process in the presence of an amphiphilic derivative of chitosan. The applied synthetic method led to the formation of a hydrophobic layer on the surface of nanoparticles that enabled their loading in the hydrophobic liquid inside of the polymer-based capsules. The average diameter of nanoparticles was determined to be equal to 15 nm, and they were thoroughly characterized using X-ray diffraction (XRD), magnetometry, and Mössbauer spectroscopy. A core–shell structure consisting of a wüstite core and maghemite-like shell was revealed, resulting in an exchange bias effect and a considerable magnetocrystalline anisotropy at low temperatures and a superparamagnetic behavior at room temperature. Importantly, superparamagnetic behavior was observed for the aqueous dispersion of the nanocapsules loaded with the superparamagnetic nanoparticles, and the dispersion was shown to be very stable (at least 48 weeks). The results were analyzed and discussed with respect to the potential future applications of these nanoparticles and nanocapsules based on biopolymers as platforms designed for the magnetically navigated transport of encapsulated hydrophobic substances.

Effect of Gd-substitution at Y-site on the structural, magnetic and dielectric properties of Y1-xGdxMnO3 (x=0, 0.05) nanoparticles

2014 ◽  
Vol 1675 ◽  
pp. 121-128
Author(s):  
Samta Chauhan ◽  
Saurabh Kumar Srivastava ◽  
Amit Singh Rajput ◽  
Ramesh Chandra
Keyword(s):  
Dielectric Properties ◽  
Average Particle Size ◽  
Hexagonal Structure ◽  
Average Particle ◽  
X Ray Diffraction ◽  
Bias Effect ◽  
Exchange Bias Effect ◽  
Conventional Solid State Reaction ◽  
Transmission Electron Microscopy Analysis ◽  
X Ray

ABSTRACTEffect of Gd substitution at Y-site on the structural and magnetic properties of Y1-xGdxMnO3 (x=0, 0.05) nanoparticles prepared by conventional solid state reaction method has been studied. The structural study using X-ray diffraction pattern indicates the hexagonal structure with P63cm space group for all the samples. The average particle size for all the samples lies in the range of 30-40 nm as confirmed by X-ray diffraction and transmission electron microscopy analysis. The change in a and c lattice parameters confirm the substitution of Gd at Y-site. Magnetization versus temperature measurements show enhanced magnetic moment and an increase in Neel temperature with Gd-doping. Spin glass behavior is observed at low temperature in all the samples. Exchange bias effect has been observed at 5 K after field cooling the samples which is ascribed to the formation of antiferromagnetic-ferromagnetic (AFM-FM) core-shell structure of the nanoparticles. A significant improvement in the dielectric properties of Gd-doped samples has also been observed.

Structural, Morphological, Magnetic and Self-Heating Studies of One-Step Polyol Synthesized Manganese Ferrite (MnFe2O4) Nanoparticles

2019 ◽  
Vol 19 (01) ◽  
pp. 1950003
Author(s):  
P. R. Ghutepatil ◽  
S. H. Pawar
Keyword(s):  
Room Temperature ◽  
Synthesis Method ◽  
Average Crystallite Size ◽  
Superparamagnetic Nanoparticles ◽  
Polyol Synthesis ◽  
X Ray Diffraction ◽  
Self Heating ◽  
Transmission Electron ◽  
One Step ◽  
Mnfe2o4 Nanoparticles

In this paper, uniform and superparamagnetic nanoparticles have been prepared using one-step polyol synthesis method. Structural, morphological and magnetic properties of obtained MnFe2O4 nanoparticles have been investigated by using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscope (FE-SEM), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM) and thermogravimetric analysis (TGA) techniques. Structural investigation showed that the average crystallite size of obtained nanoparticles was about 10[Formula: see text]nm. Magnetic study revealed that the nanoparticles were superparamagnetic at room temperature with magnetization 67[Formula: see text]emu/g at room temperature. The self-heating characteristics of synthesized MnFe2O4 nanoparticles were studied by applying external AC magnetic field of 167.6 to 335.2[Formula: see text]Oe at a fixed frequency of 265[Formula: see text]kHz. The SAR values of MnFe2O4 nanoparticles were calculated for 2, 5, 10[Formula: see text]mg[Formula: see text]mL[Formula: see text] concentrations and it is observed that the threshold hyperthermia temperature is achieved for all concentrations.

Antisite-disorder driven large exchange bias effect in phase separated La1.5Ca0.5CoMnO6 double perovskite

2017 ◽  
Vol 428 ◽  
pp. 86-91 ◽  
Author(s):  
R.C. Sahoo ◽  
D. Paladhi ◽  
Papri Dasgupta ◽  
A. Poddar ◽  
Ripandeep Singh ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Double Perovskite ◽  
Bias Effect ◽  
Exchange Bias Effect ◽  
Antisite Disorder

Analysis of exchange bias effect of NiO+NiFe2O4 composites

2010 ◽  
Vol 322 (1) ◽  
pp. 79-83 ◽  
Author(s):  
J.H. He ◽  
S.L. Yuan ◽  
S.Y. Yin ◽  
K.L. Liu ◽  
P. Li ◽  
...  
Keyword(s):  
Exchange Bias ◽  
Bias Effect ◽  
Exchange Bias Effect

Preparation of NiO Microspheres by Hydrothermal Method and its Electrochemical Capacitive Properties

2015 ◽  
Vol 814 ◽  
pp. 81-85 ◽  
Author(s):  
Qian Qian Li ◽  
Run Hua Fan ◽  
Ke Lan Yan ◽  
Kai Sun ◽  
Xu Ai Wang ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Electrochemical Impedance ◽  
Specific Capacity ◽  
Rate Capability ◽  
Average Diameter ◽  
Three Dimensions ◽  
Electrochemical Characteristics ◽  
X Ray Diffraction ◽  
High Specific Capacity ◽  
Capacitive Properties

The precursor Ni (OH)2 was synthesized by a simple hydrothermal method with hexamethylenetetramine ((CH2)6N4) as precipitant and template, and then NiO was gained after calcination. The phase and morphology of the synthesized product were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM), and the electrochemical capacitive characterization was performed using cyclic voltammetry (CV), chronopotentiometry and electrochemical impedance spectroscopy (EIS) in a 6mol/L KOH aqueous solution electrolyte. The result shows that spherical NiO without impurity was synthesized, the average diameter of the spheres is 5 um and these spheres were constructed by the interactive arrangement of many nanoflakes in three dimensions. This kind of NiO shows the typical electrochemical characteristics of pseudo capacitance with high specific capacity and excellent rate capability. The specific capacity can reach 515F/g at the current density of 1A/g

Exchange bias effect in nickel zinc ferrite–mesoporous silica nanocomposites

2013 ◽  
Vol 332 ◽  
pp. 98-102 ◽  
Author(s):  
Shilpi Banerjee ◽  
Partha Hajra ◽  
Mykanth Reddy Mada ◽  
Asim Bhaumik ◽  
Sri Bandyopadhyay ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Exchange Bias ◽  
Zinc Ferrite ◽  
Bias Effect ◽  
Exchange Bias Effect ◽  
Silica Nanocomposites ◽  
Nickel Zinc

Fabrication and repair of GaN nanorods by plasma etching with self-assembled nickel nanomasks

2021 ◽  
Author(s):  
Shiying Zhang ◽  
Lei Zhang ◽  
Yueyao Zhong ◽  
Guodong Wang ◽  
Qingjun Xu
Keyword(s):  
Inductively Coupled Plasma ◽  
Average Diameter ◽  
Etching Time ◽  
X Ray Diffraction ◽  
Plasma Etch ◽  
Inductively Coupled ◽  
Icp Etching ◽  
Self Organized ◽  
Gan Film ◽  
Koh Etching

High crystal quality GaN nanorod arrays were fabricated by inductively coupled plasma (ICP) etching using self-organized nickel (Ni) nano-islands mask on GaN film and subsequent repaired process including annealing in ammonia and KOH etching. The Ni nano-islands have been formed by rapid thermal annealing, whose density, shape, and dimensions were regulated by annealing temperature and Ni layer thickness. The structural and optical properties of the nanorods obtained from GaN epitaxial layers were comparatively studied by high-resolution X-ray diffraction (HRXRD), Raman spectroscopy and photoluminescence (PL). The results indicate that damage induced by plasma can be successfully healed by annealing in NH3 at 900 °C. The average diameter of the as-etched nanorod was effectively reduced and the plasma etch damage was removed after a wet treatment process in a KOH solution. It was found that the diameter of the GaN nanorod was continuously reduced and the PL intensity first increased, then reduced and finally increased as the KOH etching time sequentially increased.

Large exchange bias effect in NiFe2O4/CoO nanocomposites

2018 ◽  
Vol 5 (3) ◽  
pp. 035029 ◽  
Author(s):  
Rajendra Mohan ◽  
Mritunjoy Prasad Ghosh ◽  
Samrat Mukherjee
Keyword(s):  
Exchange Bias ◽  
Bias Effect ◽  
Exchange Bias Effect
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