scholarly journals Role of Zn And Polyaniline In Magnetic Nanocomposites And Enhanced Arsenic Adsorption Capacity In Wastewater

2021 ◽  
Author(s):  
Tran Minh Thi ◽  
Nguyen Mau Lam ◽  
Do Khanh Tung ◽  
Nguyen Manh Nghia ◽  
Duong Quoc Van ◽  
...  
Keyword(s):  
Grain Size ◽  
Adsorption Capacity ◽  
Relative Pressure ◽  
Arsenic Adsorption ◽  
Saturation Magnetic Moment ◽  
Structure Of Nanoparticles ◽  
Bet Method ◽  
Xrd Patterns ◽  
20 Nm

Abstract Polyaniline/Fe0.90Zn0.10Fe2O4 (PANI/Zn0.10Fe2.90O4) nanocomposites were synthesized by a chemical method and an onsite polymerization method. XRD patterns showed that the Zn0.10Fe2.90O4 grain size about 12 nm, while TEM image showed grain size from 10 to 20 nm. The results of Raman spectra and DTA analyses showed that PANI participated in part of the PANI/Zn0.10Fe2.90O4 nanocomposite samples. The grain size of PANI/Zn0.10Fe2.90O4 samples measured by SEM was about 35–50 nm. These results demonstrated the shell–core structures of the nanocomposite material. The magnetization measurements at room temperature showed that in 1250 Oe magnetic field, the saturation magnetic moment of PANI/Zn0.10Fe2.90O4 samples decreased from 71.2 to 42.3 emu/g when the PANI concentration increased from 0 % to 15 %. The surface area and porous structure of nanoparticles were investigated by the BET method at 77 K and a relative pressure P/P0 of about 1. The arsenic adsorption capacity of the PANI/Zn0.10Fe2.90O4 sample with the PANI concentration of 5 % was better than that of Fe3O4 and Zn0.10Fe2.90O4 in a solution of pH 7. In the solution with pH P14, the arsenic adsorption of magnetic nanoparticles was insignificant. Due to substitution of Fe ions by Zn transition metal and coating polyaniline, these materials could be reabsorbed and reused.

Strength and Ductility in Electrodeposited Nanocrystalline Nickel

2009 ◽  
Vol 633-634 ◽  
pp. 411-420 ◽  
Author(s):  
Heather W. Yang ◽  
Farghalli A. Mohamed
Keyword(s):  
Grain Size ◽  
Grain Growth ◽  
Annealing Treatment ◽  
Average Grain Size ◽  
Annealing Twins ◽  
Grain Distribution ◽  
Small Grains ◽  
20 Nm ◽  
Strength And Ductility

Electrodeposited nanocrystalline (nc) Ni having an average grain size of 20 nm was annealed at 443 K for different holding times. An examination of the microstructure following annealing showed three important features. First, all annealed samples exhibited abnormal grain growth, which was manifested by the presence of large grains that were surrounded by regions of small grains (bimodal grain distributions). Second, annealing twins existed in the large grains of the samples that showed a bimodal grain distribution. Third, by estimating the density of annealing twin, it was found that annealing nc-Ni at 443 K resulted in a maximum twin density after 5h. Following annealing treatment, specimens with different volume fractions of twins were tested under uniaxial tension at 393 K and a strain rate of 10-4 s-1. The results showed that both strength and ductility in nc-Ni attained maximum values after annealing for 5h. The role of both bimodal grain distributions and annealing twins in enhancing ductility and strength was discussed.

Field-dependent Morin Transition and Temperature-Dependent Spin-flop in Synthetic Hematite Nanoparticles

2019 ◽  
Vol 16 ◽  
Author(s):  
Ihab M. Obaidat ◽  
Sulaiman Alaabed ◽  
Imad A. Al-Omari ◽  
Venkatesha Narayanaswamy ◽  
Bashar Issa ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Transition Temperature ◽  
Temperature Dependent ◽  
Morin Transition ◽  
Hematite Nanoparticles ◽  
Xrd Patterns ◽  
20 Nm ◽  
Applied Fields ◽  
Nano Size

Background: In nano-size α-Fe2O3 particles, Morin transition temperature was reported to be suppressed. This suppression of the TM in nano-size α-Fe2O3 was suggested to be due to high internal strain and to the enhanced role of surface spins because of the enhanced surface to volume ratio. It was reported that for nanoparticles of diameters less than 20 nm, no Morin transition was observed and the antiferromagnetic phase disappears. In addition, annealing of samples was reported to result in both an increase of TM and a sharper transition which were attributed to reduction in de¬fects, crystal growth, or both. Objective: In this work we investigated the role of applied magnetic field on TM, the extent of the Morin transition, thermal hysteresis, and the spin-flop field in synthetic α-Fe2O3 nanoparticles of diameter around 20 nm. Methods: Hematite nanoparticles were synthesized using sol-gel method. Morphology and structural studies of the particles were done using TEM, and XRD, respectively. The XRD patterns confirm that the particles are hematite with a very small maghemite phase. The average size of the nanoparticles is estimated from both TEM images and XRD patterns to be around 20 nm. The magnetization versus temperature measurements were conducted upon heating from 5 K to 400 K and cooling down back to 5 K at several applied fields between 50 Oe and 500 Oe. Magnetization versus magnetic field measurements between -5 T and +5 T were conducted at several temperatures in the temperature range of 2-300 K. Results: We report three significant findings in these hematite nanoparticles. First, we report the occurrence of Morin transition in hematite nanoparticles of such size. Second, we report the slight field dependence of Morin transition temperature. Third, we report the strong temperature dependence of the spin-flop. Zero-field-cooled magnetization versus temperature measurements were conducted at several applied magnetic fields. Conclusion: From the magnetization versus temperature curves, Morin transition was observed to occur at all applied fields at Morin transition temperature, TM which is around 250 K with slight field dependence. From the magnetization versus magnetic field curves, spin-flop in the antiferromagnetic state was observed and found to be strongly temperature dependent. The results are discussed in terms of three components of magnetic phase in our sample. These are, the paramagnetic, soft ferromagnetic, and hard ferromagnetic components.

The Role of Disorder in the Magnetic Properties of Mechanically Milled Nanostructured Alloys

2001 ◽  
Vol 674 ◽  
Author(s):  
Diandra L. Leslie-Pelecky ◽  
Elaine M. Kirkpatrick ◽  
Tom Pekarek ◽  
Richard L. Schalek ◽  
Paul Shand ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnetic Properties ◽  
Spin Glass ◽  
Defect Formation ◽  
Fold Increase ◽  
Nanostructured Alloys ◽  
Glassy Behavior ◽  
Mean Grain Size ◽  
20 Nm

ABSTRACTMechanical milling provides a unique means of studying the influence of grain size and disorder on the magnetic properties of nanostructured alloys. This paper compares the role of milling in the nanostructure evolution of two ferromagnets – SmCo5 and GdAl2 – and the subsequent impact of nanostructure on magnetic properties and phase transitions. The ferromagnetic properties of SmCo5 are enhanced by short (< 2 hours) milling times, producing up to an eight-fold increase in coercivity and high remanence ratios. The coercivity increase is attributed to defect formation and strain. Additional milling increases the disorder and produces a mix of ferromagnetic and antiferromagnetic interactions that form a magnetically glassy phase. GdAl2, which changes from ferromagnetic in its crystalline form to spin-glass-like in its amorphous form, is a model system for studying the dependence of magnetically glassy behavior on grain size and disorder. Nanostructured GdAl2 with a mean grain size of 8 nm shows a combination of ferromagnetic and magnetically glassy behavior, in contrast to previous studies of nanostructured GdAl2 with a grain size of 20 nm that show only spin-glass-like behavior.

Grain Size Effect in the Electrical Properties of Nanostructured Functional Oxides through Pressure Modification of the Spark Plasma Sintering Method

2011 ◽  
Vol 484 ◽  
pp. 107-116 ◽  
Author(s):  
D.V. Quach ◽  
S. Kim ◽  
R.A. De Souza ◽  
Manfred Martin ◽  
Z.A. Munir
Keyword(s):  
Grain Size ◽  
Grain Boundary ◽  
Spark Plasma Sintering ◽  
Functional Oxides ◽  
Boundary Area ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
20 Nm ◽  
Sintering Method

Through the use of a high-pressure modification of the spark plasma sintering method, it was possible to consolidate functional oxides (yttria- stabilized zirconia and doped ceria) to high densities and retain a grain size of < 20 nm. The role of the pressure on densification and on the grain size of the sintered samples was demonstrated. The pressure had a marked effect on density at relatively low temperature but an insignificant effect at relatively high temperature. It was found that when prepared with such small grain sizes, these oxides conduct protonically even at temperatures as low as room temperature. The dependence of the protonic conductivity is stronger dependence on grain size than what can be anticipated from a geometric consideration based on an increase in grain boundary area. This observation strongly suggests that factors other than an increase in grain boundary area play a role, a consideration that is being further investigated.

scholarly journals Laser Heating Study of the High-Temperature Interactions in Nanograined Uranium Carbides

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5568
Author(s):  
Sanjib Chowdhury ◽  
Dario Manara ◽  
Oliver Dieste-Blanco ◽  
Davide Robba ◽  
António Pereira Gonçalves
Keyword(s):  
Grain Size ◽  
Nuclear Materials ◽  
Nuclear Fuels ◽  
Crystalline Materials ◽  
Grain Sizes ◽  
Effective Role ◽  
20 Nm ◽  
Laser Heated ◽  
Temperature Interactions

Nanograined nuclear materials are expected to have a better performance as spallation targets and nuclear fuels than conventional materials, but many basic properties of these materials are still unknown. The present work aims to contribute to their better understanding by studying the effect of grain size on the melting and solid–solid transitions of nanograined UC2−y. We laser-heated 4 nm–10 nm grain size samples with UC2−y as the main phase (but containing graphite and UO2 as impurities) under inert gas to temperatures above 3000 K, and their behavior was studied by thermal radiance spectroscopy. The UC2−y solidification point (2713(30) K) and α-UC2 to β-UC2 solid–solid transition temperature (2038(10) K) were observed to remain unchanged when compared to bulk crystalline materials with micrometer grain sizes. After melting, the composite grain size persisted at the nanoscale, from around 10 nm to 20 nm, pointing to an effective role of carbon in preventing the rapid diffusion of uranium and grain growth.

Development and Characterization of Amine-Clay Hybrid Adsorbents for CO2 Capture

2016 ◽  
Vol 1133 ◽  
pp. 547-551 ◽  
Author(s):  
Ali E.I. Elkhalifah ◽  
Mohammad Azmi Bustam ◽  
Azmi Mohd Shariff ◽  
Sami Ullah ◽  
Nadia Riaz ◽  
...  
Keyword(s):  
Adsorption Capacity ◽  
Surface Area ◽  
Surface Properties ◽  
Molar Mass ◽  
Adsorption Ability ◽  
Stepwise Increase ◽  
Inverse Effect ◽  
Bet Method ◽  
Sodium Form

The present work aims at a better understanding of the influences of the intercalated mono-, di- and triethanolamines on the characteristics and CO2 adsorption ability of sodium form of bentonite (Na-bentonite). The results revealed that the molar mass of intercalated amines significantly influenced the structural and surface properties as well as the CO2 adsorption capacity of Na-bentonite. In this respect, a stepwise increase in the d-spacing of Na-bentonite with the molar mass of amine was recorded by XRD technique. However, an inverse effect of the molar mass of amine on the surface area was confirmed by BET method. CO2 adsorption experiments on amine-bentonite hybrid adsorbents showed that the CO2 adsorption capacity inversly related to the molar mass of amine at 25 ͦC and 101 kPa. Accordingly, Na-bentonite modified by monoethanolammonium cations adsorbed as high as 0.475 mmol CO2/g compared to 0.148 and 0.087 mmol CO2/g for that one treated with di- and triethanolammonium cations, respectively.

scholarly journals On the role of grain size on slurry erosion behavior of a novel medium-carbon, low-alloy pipeline steel after induction hardening

Wear ◽  
2021 ◽  
pp. 203678
Author(s):  
Vahid Javaheri ◽  
Oskari Haiko ◽  
Saeed Sadeghpour ◽  
Kati Valtonen ◽  
Jukka Kömi ◽  
...  
Keyword(s):  
Grain Size ◽  
Pipeline Steel ◽  
Induction Hardening ◽  
Slurry Erosion ◽  
Medium Carbon ◽  
Erosion Behavior

TiO2-pillared magadiite and its arsenic adsorption capacity

2019 ◽  
Vol 26 (1) ◽  
pp. 311-318
Author(s):  
Sarah Louise S. Atulba ◽  
Jeong Hun Jang ◽  
Man Park
Keyword(s):  
Adsorption Capacity ◽  
Arsenic Adsorption

Role of Sm3+ on Mn Nanoparticles Embedded Zinc Tellurite Glasses Absorption and Luminescence Characteristic

2020 ◽  
Vol 981 ◽  
pp. 73-77
Author(s):  
Nurul Ainaa Najihah Busra ◽  
Ramli Arifin ◽  
Sib Krishna Ghoshal ◽  
Rodziah Nazlan
Keyword(s):  
Electric Field Effect ◽  
Tellurite Glasses ◽  
Solid State Lasers ◽  
Absorption Bands ◽  
Precise Control ◽  
Amorphous Nature ◽  
Xrd Patterns ◽  
Inorganic Glasses ◽  
Rare Earth Doped

Enhancing the optical performance of rare earth doped binary inorganic glasses is an ever-demanding quest. Samarium (Sm3+) doped zinc tellurite glasses containing Manganese (Mn) nanoparticles (NPs) with composition (59-x)TeO2-20ZnCl2-10ZnO-10Li2O-1Sm2O3-(x)Mn3O4, where x = 0 to 0.06 mol% are prepared by melt quenching technique. The role played by Mn NPs in enhancing the optical behaviors are analyzed and discussed. The XRD patterns confirm the amorphous nature of the glass. The UV-Vis-NIR spectra reveal seven prominent absorption bands of Sm3+ ions. The photoluminescence spectra display four peaks corresponding to 4G5/2→6H5/2, 4G5/2 →6H7/2, 4G5/2→6H9/2 and 4G5/2 →6H11/2 transitions. An enhancement in the luminescence intensity is observed up to 0.05 mol% concentration of NPs and the intensity quenches beyond it. The enhancement is attributed to local electric field effect of NPs in the proximity of Sm3+ ion. Our results on improved optical response via precise control of NPs contents may be useful for the development of solid state lasers and amplifiers.

Size-Dependence of Photoluminescence Property of ZnO Nanoparticles

2014 ◽  
Vol 887-888 ◽  
pp. 143-146 ◽  
Author(s):  
Xiao Fang Wang ◽  
Yun Liang Fang ◽  
Tian Le Li ◽  
Fu Juan Wang
Keyword(s):  
Grain Size ◽  
Lower Energy ◽  
Size Dependence ◽  
Surface States ◽  
Photoluminescence Property ◽  
Precipitation Method ◽  
Pl Spectra ◽  
Broadband Emission ◽  
Band Emission ◽  
20 Nm

Nanometer-sized ZnO crystals with the diameter from 20 nm to 110 nm were prepared by homogenous precipitation method (HPM). The photoluminescence (PL) spectra of as-prepared nanoparticles under excitation at the wavelength of 320 nm were detected. The PL spectra were fitted with Gaussian curves, in which a good fitting consisting of six Gaussian peaks was obtained. We observed that the multi-peak centers do not change much, while the relative amplitude of Gaussian combination to the band-to-band emission decreases rapidly with the increased grain size. It shows that the broadband emission at the lower energy is associated with the surface states.

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