Structural, Magnetic and Hyperfine Properties of Molybdenum Dioxide-Hematite Mixed Oxide Nanostructures

MRS Advances ◽  
2018 ◽  
Vol 3 (47-48) ◽  
pp. 2887-2892
Author(s):  
Richard Trotta ◽  
Felicia Tolea ◽  
Mihaela Valeanu ◽  
Lucian Diamandescu ◽  
Agnieszka Grabias ◽  
...  
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Mechanochemical Activation ◽  
Magnetic Measurements ◽  
Activation Process ◽  
Zero Field ◽  
Molybdenum Dioxide ◽  
Nanoparticle System ◽  
Ball Milling Time ◽  
Field Cooling

ABSTRACTMoO2-Fe2O3 nanoparticle system was successfully synthesized by mechanochemical activation of MoO2 and α-Fe2O3 equimolar mixtures for 0-12 hours of ball milling time. The study aims at exploring the formation of magnetic oxide semiconductors at the nanoscale. X-ray powder diffraction (XRD), Mössbauer spectroscopy and magnetic measurements were used to study the phase evolution of MoO2-Fe2O3 nanoparticle system under the mechanochemical activation process. The Mössbauer studies showed that the spectrum of the mechanochemically activated composites evolved from a sextet for hematite to sextet and a doublet upon duration of the milling process with molybdenum dioxide. Recoilless fraction was determined using our dual absorber method and was found to decrease with increasing ball milling time. Magnetic measurements recorded at 5 and 300 K in an applied magnetic field of 50,000 Oe showed the magnetic properties in the antiferromagnetic and canted ferromagnetic states. The Morin transformation was evidenced by zero-field cooling-field cooling (ZFC-FC) measurements in 200 Oe and the transformation characteristic temperatures were shifted to lower values.

Synthesis and Characterization of Indium Oxide Doped Hematite xIn2O3·(1-x)α-Fe2O3 Solid Solution

2011 ◽  
Vol 1309 ◽  
Author(s):  
Monica Sorescu ◽  
Tianhong Xu ◽  
Lucian Diamandescu
Keyword(s):  
Solid Solution ◽  
Ball Milling ◽  
Indium Oxide ◽  
Milling Time ◽  
Mechanochemical Activation ◽  
Synthesis And Characterization ◽  
Quadrupole Split ◽  
Grain Sizes ◽  
Ball Milling Time

ABSTRACTIndium oxide-doped hematite xIn2O3·(1-x)α-Fe2O3 (x = 0.1-0.7) solid solution systems were synthesized using mechanochemical activation. The microstructures, magnetic and thermal properties of the system were dependent on In2O3 molar concentration x and ball milling time. XRD results showed that the completion of In3+ substitution of Fe3+ in hematite lattice occurs after 12 h ball milling for x = 0.1. For x = 0.3, 0.5 and 0.7, the substitutions between In3+ and Fe3+ into hematite and In2O3 lattices occur simultaneously. The lattice parameters of hematite and In2O3 vary as a function of ball milling time. The change in these parameters was due to ions substitution between In3+and Fe3+ and the decrease in grain sizes. Mössbauer spectra of the system with x = 0.3 were fitted with three sextets and two quadrupole-split doublets after milling, representing In3+ substitution of Fe3+ in hematite lattice and Fe3+ substitution of In3+ in two different sites of In2O3 lattice. TGA results showed that the hematite decomposition is enhanced due to the smaller hematite grain size. The crystallization of hematite and In2O3 was suppressed with the drops of enthalpy values due to the stronger solid-solid interactions after ball milling. These caused gradual In3+-Fe3+ substitution in hematite/In2O3 lattices.

Europium Oxide-Hematite Magnetic Ceramic Nanoparticles

MRS Advances ◽  
2015 ◽  
Vol 1 (3) ◽  
pp. 215-220 ◽  
Author(s):  
Monica Sorescu ◽  
Lucian Diamandescu ◽  
John DiGnazio ◽  
Tianhong Xu
Keyword(s):  
Milling Time ◽  
Mechanochemical Activation ◽  
Phase Evolution ◽  
Milling Process ◽  
Europium Oxide ◽  
Activation Process ◽  
Solid Solution Formation ◽  
Biomedical Sensing ◽  
Solution Formation ◽  
Nanoparticle System

ABSTRACTNanoparticle system with the composition xEu2O3-(1-x)α-Fe2O3 (x = 0.1 and 0.5) was successfully synthesized by mechanochemical activation of Eu2O3 and α-Fe2O3 mixtures for 0-12 hours of ball milling time. The study is of relevance to catalysis, biomedical, sensing and energy-related applications. 57Fe and 151Eu Mössbauer spectroscopy were used to investigate the phase evolution, solid solution formation and hyperfine parameters of xEu2O3-(1-x)α-Fe2O3 nanoparticle system under the mechanochemical activation process. The 57Fe Mössbauer studies showed that the spectrum of the ball milled samples evolved from a sextet for hematite to sextets and a doublet upon duration of the milling process with europium oxide. This indicated the formation of the EuFeO3 perovskite for large x values and long milling times. The 151Eu Mössbauer investigations showed that the isomer shift decreased with increasing milling time for all molar concentrations employed.

Experimental Investigation and Micro-Structural Evolution Analysis of CNT & Fly Ash Reinforced Aluminium Matrix Composites

2015 ◽  
Vol 830-831 ◽  
pp. 429-432 ◽  
Author(s):  
Udaya ◽  
Peter Fernandes
Keyword(s):  
Mechanical Properties ◽  
Experimental Investigation ◽  
Fly Ash ◽  
Ball Milling ◽  
Milling Time ◽  
Structural Evolution ◽  
Matrix Composites ◽  
Evolution Analysis ◽  
Ball Milling Time ◽  
Al Matrix

The paper illustrates Carbon nanotubes reinforced pure Al (CNT/Al) composites and fly ash reinforced pure Al (FA/Al) composites produced by ball-milling and sintering. Microstructures of the fabricated composite were examined and the mechanical properties of the composites were tested and analysed. It was indicated that the CNTs and fly ash were uniformly dispersed into the Al matrix as ball-milling time increased with increase in hardness.

Preparation of High Density BaZr0.97Y0.03O3-δ Ceramic and its Interaction with Titanium Melt

2018 ◽  
Vol 768 ◽  
pp. 261-266 ◽  
Author(s):  
Ju Yun Kang ◽  
Guang Yao Chen ◽  
Bao Tong Li ◽  
Zi Wei Qin ◽  
Xiong Gang Lu ◽  
...  
Keyword(s):  
Particle Size ◽  
Ball Milling ◽  
Milling Time ◽  
Sintered Pellet ◽  
Conventional Solid State Reaction ◽  
Industrial Grade ◽  
Minimum Particle Size ◽  
Ni Alloy ◽  
Improved Stability ◽  
Ball Milling Time

In this paper, the BaZrO3(BZ) and BaZr0.97Y0.03O3-δ(BZY3) powders were prepared by using the industrial grade BaCO3, ZrO2and Y2O3powders combining the conventional solid state reaction. The BaZrO3(BZ) and BaZr0.97Y0.03O3-δ(BZY3) ceramics were fabricated at 1750°C. The effect of ball milling time and sintering aid (TiO2) on the sinterability of BaZr0.97Y0.03O3-δ(BZY3) ceramics were investigated, and the improved stability of BaZrO3refractory with Y2O3additive were studied according to the refractory-metal interaction. The results revealed that the particle size of BZY3 powders decreased first and then increased with the increasing of ball milling time from 6h to 12h, and the minimum particle size was only 2.252μm at 8h. When 2wt.%TiO2was added, the sintered pellet of BZY3 was the most densest and the relative density was above 95%. After melting the Ti2Ni alloy on the BZY and BZ ceramics, the thickness erosion layer of BaZrO3and BZY3refractories and Ti2Ni alloy is approximately 50μm and 20μm respectively, showing that BZY3 was more stable than BaZrO3refractory.

Surface Effects on the Magnetic Behavior of Nanocrystalline Nickel Ferrites: The Effect of Surface Roughness and Dilution

2005 ◽  
Vol 877 ◽  
Author(s):  
H. Nathani ◽  
R.D.K. Misra ◽  
W.F. Egelhoff
Keyword(s):  
Surface Roughness ◽  
Nickel Ferrite ◽  
Magnetic Measurements ◽  
Magnetic Behavior ◽  
Magnetic Data ◽  
Zero Field ◽  
Nanocrystalline Nickel ◽  
Polyethylene Matrix ◽  
Dilution Effects ◽  
Field Cooling

AbstractThe paper describes the surface roughness and dilution effects on the magnetic behavior of nanocrystalline nickel ferrites studied by SQUID magnetometer. Two different kinds of measurements were performed: (a) zero-field cooling (ZFC) and field cooling (FC) magnetization versus temperature and (b) magnetization as a function of the applied field. The analysis of magnetic measurements indicate that while the superparamagnetic behavior is retained by nanocrystalline ferrites of different surface roughness (0.8-1.8 nm) at 300K, the hysteresis loop at 2K becomes non-squared and the coercivity increases with increase in surface roughness. This behavior is discussed in terms of broken bonds and degree of surface spin disorder. In diluted dispersion systems containing 10-40% nickel ferrite in a polyethylene matrix, the interparticle attractions continue to be dominant even when the concentration of nickel ferrite is 10 wt.% in the diluted system. The general magnetic behavior of diluted dispersion system is similar to the undiluted system; however, coercivity, remanence, and saturation magnetization are altered. These changes in the magnetic data are ascribed to magnetization interactions that encourage flux closure configuration.

Mechanochemical Synthesis of Novel Sensor Materials

2009 ◽  
Vol 1226 ◽  
Author(s):  
Monica Sorescu ◽  
Lucian Diamandescu ◽  
Adelina Tomescu
Keyword(s):  
Ball Milling ◽  
Milling Time ◽  
Gas Sensing ◽  
Mechanochemical Activation ◽  
Magnetic Characteristics ◽  
X Ray Diffraction ◽  
Recoilless Fraction ◽  
X Ray ◽  
Immiscible System ◽  
Sensing Applications

AbstractThe xZnO-(1-x)alpha-Fe2O3 and xZrO2-(1-x)alpha-Fe2O3 nanoparticles systems have been obtained by mechanochemical activation for x=0.1, 0.3 and 0.5 and for ball milling times ranging from 2 to 24 hours. Structural and magnetic characteristics of the zinc and zirconium-doped hematite systems were investigated by X-ray diffraction (XRD), Mössbauer spectroscopy and conductivity measurements. Using the dual absorber method, the recoilless fraction was derived as function of ball milling time for each value of the molar concentration involved. As ZnO is not soluble in hematite in the bulk form, the present study clearly illustrates that the solubility limits of an immiscible system can be extended beyond the limits in the solid state by mechanochemical activation. Moreover, this synthetic route allowed us to reach nanometric particle dimensions, which makes these materials very important for gas sensing applications.

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