Preparation and Magnetic Properties of α-MnO2 Nanoparticles

2011 ◽  
Vol 492 ◽  
pp. 264-267 ◽  
Author(s):  
Bao Ling Zhu ◽  
Qiherima ◽  
Li Lv ◽  
Xiao Jing Wang
Keyword(s):  
Hysteresis Loop ◽  
Magnetic Hysteresis ◽  
Average Particle Size ◽  
Magnetic Hysteresis Loop ◽  
Molar Ratio ◽  
Thermal Method ◽  
Average Particle ◽  
Straight Line ◽  
Lower Temperature ◽  
Average Size

α-MnO2 nanoparticles with the average size about 22-29 nm were synthesized by hydro- thermal method. The as-synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform-Infrared Rediation (FT-IR) and thermogravimetric-differential thermal analysis (TG- DTA). We find that the average particle size of α-MnO2 is increased with the reaction temperature increasing. The diluent reactant is beneficial for the growth of α-MnO2. The smaller the molar ratio of K/Mn is, the more stable α-MnO2 phase is. The Neel temperature (TN) of nano-α-MnO2 is 5.0K obtained by the magnetic susceptibility determination, lower then the value of 24.5K for MnO2 single crystal phase. The magnetic hysteresis loop can be observed obviously at T = 5.0 K. It indicated that when the particles are at the level of nano-size level, the anti-ferromagnetic MnO2 showed the ferromagnetic nature at the lower temperature. When the temperature is high up to 60.0K, the magnetic hysteresis loop can't be observed. While when the temperature is at 120.0K, a straight line of magnetic hysteresis loop is obtained, indicating the paramagnetic magnetic nature of our sample.

Mesoporous Silica Nanoparticles of Hydroxyurea: Potential

2020 ◽  
Vol 10 ◽  
Author(s):  
Kumar Nishchaya ◽  
Swatantra K.S. Kushwaha ◽  
Awani Kumar Rai
Keyword(s):  
Drug Release ◽  
Silica Nanoparticles ◽  
Mesoporous Silica Nanoparticles ◽  
Release Kinetics ◽  
Average Particle Size ◽  
Silica Nanoparticle ◽  
Average Particle ◽  
Independent Variables ◽  
Lower Temperature

Background: Present malignant cancer medicines has the advancement of magnetic nanoparticles as delivery carriers to magnetically accumulate anticancer medication in malignant growth tissue. Aim: In the present investigation, a silica nanoparticles (MSNs) stacked with hydroxyurea were combined and was optimized for dependent and independent variables. Method: In this study, microporous silica nanoparticle stacked with neoplastic medication had been prepared through emulsification followed with solvent evaporation method. Prepared MSNs were optimized for dependent and independent variables. Different formulations were prepared with varying ratio of polymer, lipid and surfactant which affects drug release and kinetics of drug release pattern. The obtained MSNs were identified by FTIR, SEM, drug entrapment, in-vitro drug release, drug release kinetics study, stability testing in order to investigate the nanoparticle characteristics. Results: The percentage drug entrapment of the drug for the formulations F1, F2, F3, was found to be 27.78%, 65.52% and 48.26%. The average particle size for F2 formulation was found to be 520 nm through SEM. The cumulative drug release for the formulations F1, F2, F3 was found to be 64.17%, 71.82% and 32.68%. The formulations were found to be stable which gives controlled drug delivery for 6 hours. Conclusion: From the stability studies data it can be culminated that formulations are most stable when stored at lower temperature or in refrigerator i.e. 5˚C ± 3˚C. It can be concluded that MSN’s loaded with hydroxyurea is a promising approach towards the management of cancer due to its sustained release and less side effects.

Correlation between Anomalous Peak Effect in Magnetic Hysteresis Loop and Nanoscale Structure forNdBa2Cu3O7-δSingle-Crystal Superconductor

1996 ◽  
Vol 35 (Part 1, No. 7) ◽  
pp. 3882-3886 ◽  
Author(s):  
Masaru Nakamura ◽  
Tsukasa Hirayama ◽  
Yasuji Yamada ◽  
Yuichi Ikuhara ◽  
Yuh Shiohara
Keyword(s):  
Hysteresis Loop ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop ◽  
Peak Effect ◽  
Anomalous Peak ◽  
Nanoscale Structure

Magnetic Hysteresis Loop of Single Co Nano-islands

2008 ◽  
Vol 47 (12) ◽  
pp. 9013-9015 ◽  
Author(s):  
Guillemin Rodary ◽  
Sebastian Wedekind ◽  
Dirk Sander ◽  
Jürgen Kirschner
Keyword(s):  
Hysteresis Loop ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop

Ageing behavior study of 5Cr–0.5Mo steel by magnetic Barkhausen emissions and magnetic hysteresis loop techniques

2007 ◽  
Vol 40 (2) ◽  
pp. 173-178 ◽  
Author(s):  
J.N. Mohapatra ◽  
A.K. Panda ◽  
M.K. Gunjan ◽  
N.R. Bandyopadhyay ◽  
A. Mitra ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Magnetic Hysteresis ◽  
Magnetic Hysteresis Loop ◽  
Behavior Study

scholarly journals Effect of the polymeric coating over Fe3O4 particles used for magnetic separation

2010 ◽  
Vol 8 (5) ◽  
pp. 1041-1046 ◽  
Author(s):  
Raúl Reza ◽  
Carlos Martínez Pérez ◽  
Claudia Rodríguez González ◽  
Humberto Romero ◽  
Perla García Casillas
Keyword(s):  
Particle Size ◽  
Magnetite Nanoparticles ◽  
Average Particle Size ◽  
Spherical Shape ◽  
Polymeric Coating ◽  
Average Particle ◽  
Synthesis Conditions ◽  
Aging Conditions ◽  
Magnetite Particles ◽  
Average Size

AbstractIn this work, the synthesis of magnetite nanoparticles by two variant chemical coprecipitation methods that involve reflux and aging conditions was investigated. The influence of the synthesis conditions on particle size, morphology, magnetic properties and protein adsorption were studied. The synthesized magnetite nanoparticles showed a spherical shape with an average particle size directly influenced by the synthesis technique. Particles of average size 27 nm and 200 nm were obtained. When the coprecipitation method was used without reflux and aging, the smallest particles were obtained. Magnetite nanoparticles obtained from both methods exhibited a superparamagnetic behavior and their saturation magnetization was particle size dependent. Values of 67 and 78 emu g−1 were obtained for the 27 nm and 200 nm magnetite particles, respectively. The nanoparticles were coated with silica, aminosilane, and silica-aminosilane shell. The influence of the coating on protein absorption was studied using Bovine Serum Albumin (BSA) protein.

Fe3O4 Magnetic Preparation by Bauxite Ore Washing Fine Mud

2014 ◽  
Vol 1010-1012 ◽  
pp. 961-965
Author(s):  
Jian Qiang Xiao ◽  
Guo Wei He ◽  
Yan Jin Hu
Keyword(s):  
Particle Size ◽  
Aging Time ◽  
Average Particle Size ◽  
Xrd Analysis ◽  
Test Methods ◽  
Raw Material ◽  
Molar Ratio ◽  
Average Particle ◽  
Experimental Conditions ◽  
Particle Size Analyzer

Bauxite waste sludge as a raw material, the use of reverse chemical coprecipitation synthesize Fe3O4. Researching temperature, precipitation concentration, aging time and Fe2+/Fe3+ molar ratio effect on the particle size, morphology. Optimal experimental conditions: temperature 70 °C, the precipitant NaOH mass ratio of 10%, aging time 3h, Fe2+/Fe3+ molar ratio of 2:3. Test methods using a laser particle size analyzer, XRD analysis of the products were characterized, the product is Fe3O4, the average particle size of 0.11mm.

Exchange Bias Properties in Bulk Ni45Co5Mn38Sn12 Heusler Alloy

2014 ◽  
Vol 875-877 ◽  
pp. 272-276 ◽  
Author(s):  
Chao Jing ◽  
Ye Jun Yang ◽  
Dong Hua Yu ◽  
Zhe Li ◽  
Xiao Long Wang ◽  
...  
Keyword(s):  
Hysteresis Loop ◽  
Exchange Bias ◽  
Heusler Alloy ◽  
Magnetic Hysteresis ◽  
Hysteresis Loops ◽  
Bias Field ◽  
Magnetic Hysteresis Loop ◽  
Zero Field ◽  
Co Substitution ◽  
Exchange Bias Field

We report the exchange bias properties in the bulk Ni45Co5Mn38Sn12quaternary Heusler alloy. The ferromagnetic (FM) –antiferromagnetic (AFM) interactions get reinforced after the Co substitution for Ni in the Ni-Mn-Sn alloy, which increase the exchange bias field (HE). A maximum shift in hysteresis loops of 306 Oe was observed in the 10 kOe field cooled sample. The origin of this large exchange bias field has been discussed. Magnetic hysteresis loop obtained in the zero field cooled (ZFC) mode shows double-shifted loop, and the reason of this phenomenon has been explained in detail.

Сrystalline structure and dielectric properties of ceramic materials based on AgNbO3

2020 ◽  
Vol 63 (7) ◽  
pp. 75-78
Author(s):  
Polina A. Bezborodova ◽  
◽  
Elena M. Filonenko ◽  
Kseniya R. Erager ◽  
Anatoly V. Butakov ◽  
...  
Keyword(s):  
Rietveld Method ◽  
Average Particle Size ◽  
Ceramic Materials ◽  
Analysis Data ◽  
Molar Ratio ◽  
Average Particle ◽  
Dielectric Parameters ◽  
Low Frequencies ◽  
X Ray ◽  
Substitution Degree

Using the data of qualitative X-ray phase analysis, it was shown that in a wide concentration range at 1223 K compounds based on silver niobate are formed in the condition of the heterovalent substitution of tungsten(VI) ions for niobium(V) ions. These compounds are isomorphic to a perovskite-type structure. Microprobe analysis data allows to determine the homogeneity of the analyzed samples and the correspondence of their experimental compositions to the theoretical ones for the formula Ag1-xNb1-xWxO3. Using the data of X-ray diffraction analysis (Rietveld method) in the Crystallography Data Analysis Software – GSAS, the crystal structure of the obtained compounds was refined. The surface morphology of samples having been obtained at 1373 K was investigated by scanning electron microscopy (SEM). It was shown that with an increase of Nb5+ to W6+ substitution degree for Ag1-xNb1-xWxO3 ceramic samples in the range of the (0.2≤x≤0.8) molar ratio, the average particle size for the studied compositions grows from 1.3 to 5.2 μm, respectively. For the obtained ceramic compounds based on silver niobate with a perovskite-like structure (tetragonal distortion), the temperature-frequency dependences of dielectric parameters in the range 300-900 K were studied. It was found that samples slowly cooled from 1373 K are characterized by low values of (ε ~ 10) and loss (tgδ ~ 0.004 at f = 1 kHz) at room temperature. The ceramics obtained are characterized by relatively high values of dielectric permittivity ε at low frequencies and/or high temperatures. The dielectric parameters of the obtained ceramics are similar to the characteristics of so-called "colossal" dielectric constant materials. The revealed features of the dielectric characteristics of quenched ceramics apparently result from Maxwell-Wagner relaxation at intercrystalline contacts.

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