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nanocrystalline-materials
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A new model for the effect of grain size on the elastic modulus of nanocrystalline materials
, Article Materials Science- Poland ; Volume 27, Issue 1 , 2009 , Pages 279-285 ; 01371339 (ISSN) ; Sharif University of Technology
2009
Abstract
A new model is developed for the structure of nanocrystalline materials. Based on the developed model, a new approach for investigating the effect of grain size on the elastic moduli of nanocrystalline materials is introduced. The predictions of the model are strongly correlated with the experimental results reported in the existing literature
End-closed NiCoFe-B nanotube arrays by electroless method
, Article Materials Letters ; Volume 65, Issue 2 , 2011 , Pages 289-292 ; 0167577X (ISSN) ; Mohammadi, M ; Sadrnezhaad, S. K ; Sharif University of Technology
2011
Abstract
A novel approach is obtained during the fabrication of NiCoFe-B nanotube arrays via electroless method. Porous anodic aluminum oxide (AAO) templates fabricated by anodization of aluminum foil were sensitized using PdCl 2 solution and immersed into electroless plating baths at room temperature to produce nanotube arrays. Compositional and morphological properties of the nanotube arrays are characterized. Results indicates the formation of end-closed nanotubes with the dimension of 100-130 nm in outside diameter, which is determined by the pore size of the AAO template, and about 15 nm in thickness of tube walls. The possible formation mechanism of end-closed metallic nanotube arrays is...
Preparation and characterization of nanocrystalline misch-metal-substituted yttrium iron garnet powder by the sol-gel combustion process
, Article International Journal of Applied Ceramic Technology ; Volume 5, Issue 5 , 26 August , 2008 , Pages 464-468 ; 1546542X (ISSN) ; Madaah Hosseini, H. R ; Nemati, Z. A ; Sharif University of Technology
2008
Abstract
Nanocrystalline Y3-xMMxFe5O12 powders (MM denotes Misch-metal, x = 0.0, 0.25, 0.5, 0.75, and 1.0) were synthesized by a sol-gel combustion method. Magnetic properties and crystalline structures were investigated using X-ray diffraction (XRD), a vibrating sample magnetometer (VSM), and a scanning electron microscope. The XRD patterns showed that the single-phase garnet of Y3-xMMxFe5O12 was formed at x values ≤ 1.0. The saturation magnetization of powders increased with decreasing MM content and reached the maximum value at Y3 Fe5O12. The crystallite size of powders calcined at 800°C for 3 h was in the range of 38-53 nm. © 2008 American Ceramic Society
A new model for inverse Hall-Petch relation of nanocrystalline materials
, Article Journal of Materials Engineering and Performance ; Volume 17, Issue 5 , 2008 , Pages 662-666 ; 10599495 (ISSN) ; Dehghani, K ; Sharif University of Technology
2008
Abstract
In the present article, a new model for inverse Hall-Petch relation in nanocrystalline materials has been proposed. It is assumed that lattice distortion along grain boundaries can cause internal stresses and high internal stresses along grain boundaries can promote the grain boundary yielding. The designed model was then verified using the nanocrystalline-copper data. The minimum grain size for inverse Hall-Petch relation is determined to be about 11 nm for Cu. © 2008 ASM International
The effect of nanocrystalline tungsten oxide concentration on surface properties of dip-coated hydrophilic WO3-SiO2 thin films
, Article Journal of Physics D: Applied Physics ; Volume 40, Issue 7 , 2007 , Pages 2089-2095 ; 00223727 (ISSN) ; Azimirad, R ; Akhavan, O ; Moshfegh, A. Z ; Sharif University of Technology
2007
Abstract
WO3-SiO2 compound thin films were deposited on glass substrates using the sol-gel method, and then all the samples were dried at 100 °C and annealed at 400 °C in air. The effect of WO3 concentration on the hydrophilicity of WO3-SiO2 compound films was studied for the first time and it was shown that the films containing 85 mol% of the concentration possessed a superhydrophilic surface without UV or visible irradiation. Optical properties of the films such as transmittance, reflectance and bandgap energy were investigated using a UV-visible spectrophotometer. According to atomic force microscopy, the surface ratio was maximized in 85 mol% concentration of WO3 similar to hydrophilicity....
Modeling nano-scale grain growth of intermetallics
, Article Bulletin of Materials Science ; Volume 32, Issue 1 , 2009 , Pages 19-21 ; 02504707 (ISSN) ; Sharif University of Technology
2009
Abstract
The Monte Carlo simulation is utilized to model the nano-scale grain growth of two nanocrystalline materials, Pd81Zr19 and RuAl. In this regard, the relationship between the real time and the time unit of simulation, i.e. Monte Carlo step (MCS), is determined. The results of modeling show that with increasing time of heating, the grain sizes of both nano-crystalline materials increased as in the case of conventional materials. Moreover, it is found that for both nano-crystalline materials the relationship between the real time and MCS is in power law form, which is linear for the conventional materials. © Indian Academy of Sciences
Mechanical behavior modeling of nanocrystalline NiAl compound by a feed-forward back-propagation multi-layer perceptron ANN
, Article Computational Materials Science ; Volume 44, Issue 4 , 2009 , Pages 1231-1235 ; 09270256 (ISSN) ; Mousavi Anijdan, S. H ; Samadi, A ; Bahrami, A ; Sharif University of Technology
2009
Abstract
In this paper, an artificial neural network (ANN) model has been developed to predict the yield and tensile strengths of hot pressed NiAl intermetallic compound based on the experimental data from Albiter et al. [A. Albiter, M. Salazar, E. Bedolla, R.A.L. Drew, R. Perez, Mater. Sci. Eng. A 347 (2003) 154]. The predicted results, with a correlation relation between 0.9791 and 0.9921, show a very good agreement with the experimental values. Furthermore, the sensitivity analysis was performed to investigate the importance of the effects of chemical composition and temperature on the mechanical behavior of hot pressed NiAl intermetallic compound. © 2008 Elsevier B.V. All rights reserved
A heterogeneous strong basic nanocrystalline copper(II) oxide catalyst for efficient synthesis of 4-keto-4,5,6,7-tetrahydrobenzofurans
, Article Catalysis Communications ; Volume 10, Issue 10 , 2009 , Pages 1423-1426 ; 15667367 (ISSN) ; Sadjadi, S ; Hosseinpour, M ; Outokesh, M ; Hekmatshoar, R ; Sharif University of Technology
2009
Abstract
An efficient synthesis of tetrahydrobenzofurans is carried out in one pot through the reaction of 1,3-diketone and phenacyl bromides compound using a heterogeneous basic nano particles copper oxide catalyst. The protocol offers advantages in terms of higher yields, short reaction times, and mild reaction conditions, with reusability of the catalyst. © 2009 Elsevier B.V. All rights reserved
Evaluating Cu2SnS3nanoparticle layers as hole-transporting materials in perovskite solar cells
, Article ACS Applied Energy Materials ; Volume 4, Issue 6 , 2021 , Pages 5560-5573 ; 25740962 (ISSN) ; Mirhosseini, M ; Abdizadeh, K ; Mahdavi, S. M ; Taghavinia, N ; Sharif University of Technology
American Chemical Society
2021
Abstract
We investigate the use of simple nontoxic Cu2SnS3 (CTS) nanoparticles (NPs) as low-cost dopant-free hole-transport materials (HTMs) a substitute for spiro-OMeTAD in an n-i-p mesoscopic architecture of perovskite solar cells (PSCs). Besides, this work confirms the critical role of the crystalline phase of CTS NPs on the performance of the device. Using a facile one-pot heating-up procedure, pure zincblende and wurtzite structures of CTS NPs were obtained by sulfur element and thiourea as the sulfur source, respectively, and were dispersed in chloroform to make very stable nonpolar ink that is compatible with the perovskite. Nanoparticles with the wurtzite crystal phase showed much better...
Polyacids for producing colloidally stable amorphous calcium carbonate clusters in water
, Article Journal of Applied Polymer Science ; November , 2021 ; 00218995 (ISSN) ; Basak Kayitmazer, A ; Ahmad, A ; Ramzan, N ; Li, Y ; Xu, Y ; Sun, S ; Sharif University of Technology
John Wiley and Sons Inc
2021
Abstract
As an important precursor of crystalline phases, amorphous calcium carbonate (ACC), especially ultrasmall ACC clusters, have been attracting great interest in fundamental research, materials chemistry, as well as industrial applications. However, it is still challenging to synthesize stable ACC clusters in water that can be isolated and concentrated without severe aggregation. Herein, we report a facile dialysis method for producing colloidally stable ACC clusters that are well dispersed in water with the protection of specific polycarboxylic acids, which could be also easily deprotected by small-molecule acids like sodium citrate. Inherent proto-calcite short-range order is found to be...
Synthesis and characterization of nanocrystalline barium strontium titanate
, Article Materials Science- Poland ; Volume 28, Issue 2 , 2010 , Pages 421-426 ; 01371339 (ISSN) ; Nemati, Z. A ; Faghihi Sani, M. A ; Sharif University of Technology
2010
Abstract
Barium strontium titanate (BST) was prepared via the simple sol-gel method by using tetrabutyl ti-tanate, ethanol, citric acid and ethylene glycol as starting materials. Thermogravimetry and differential thermal analysis were used to examine the behaviour of the xerogel. The particle size of BST was approximately 21 nm, as calculated by the X-ray diffraction and confirmed by transition electron microscopy for the calcination temperature of 750 °C. It was found that the particles of BST powders calcined at 750 °C were smaller and more homogeneous and uniform than those obtained at 800 °C
Iron-borosilicate soft magnetic composites: the correlation between processing parameters and magnetic properties for high frequency applications
, Article Journal of Magnetism and Magnetic Materials ; Volume 429 , 2017 , Pages 241-250 ; 03048853 (ISSN) ; Madaah Hosseini, H .R ; Seyed Reihani, S. M ; Sharif University of Technology
Elsevier B.V
2017
Abstract
Iron-borosilicate soft magnetic composites are suitable magnetic materials for high temperature and high frequency applications. In this research two different techniques have been applied to fabricate these composites: uniaxial pressing following by sintering and spark plasma sintering. Different processing parameters including the content of borosilicate, the amount of compaction pressure and the size of iron particles have been evaluated through the study of microstructure and magnetic properties. The microstructural observations showed that the borosilicate is distributed on the iron grain boundaries enhancing the resistivity and causing the loss of eddy currents. Increasing the...
Preparation of nitrogen-doped aluminium titanate (Al2TiO5) nanostructures: Application to removal of organic pollutants from aqueous media
, Article Advanced Powder Technology ; Volume 31, Issue 8 , 2020 , Pages 3328-3341 ; Zekavat, M ; Soltaninejad, M ; Bakhshandeh, F ; Reza Madaah Hosseini, H ; Kashani, S ; Amutha, C ; Khatiboleslam Sadrnezhaad, S ; Ramakrishna, S ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Recently, aluminum titanate (Al2TiO5)-based nanostructures have been proved to serve as an efficient photocatalytic material with satisfactory photodegradation capacity. In this study, the citrate sol–gel method was used to synthesize these nanostructures and inspect the significant impacts of nitrogen-doping-originated crystalline defects on their photocatalytic performance in some details for the first time. The results indicated that the penetration of nitrogen atoms into AT crystal lattice, depending on the nitriding time and temperature, can induce a great deal of the residual stress and result in propagating the existing cracks and breaking down the particles. The XPS and FTIR results...
Compaction simulation of crystalline nano-powders under cold compaction process with molecular dynamics analysis
, Article Powder Technology ; Volume 373 , August , 2020 , Pages 741-753 ; Sameti, A. R ; Mofatteh, H ; Sharif University of Technology
Elsevier B. V
2020
Abstract
In this paper, the uniaxial cold compaction process of metal nano-powders is numerically analyzed through the Molecular Dynamics (MD) method. The nano-powders consist of nickel and aluminum nano-particles in the pure and mixed forms with distinctive contributions. The numerical simulation is performed using the different number of nano-particles, mixing ratios of Ni and Al nano-particles, compaction velocities, and ambient temperatures in the canonical ensemble until the full-dense condition is achieved. In the MD analysis, the inter-atomic interaction between metal nano-particles is modeled by the many-body EAM potential, and the interaction between frictionless rigid die-walls and metal...
Measurement modulus of elasticity related to the atomic density of planes in unit cell of crystal lattices
, Article Materials ; Volume 13, Issue 19 , 2020 , Pages 1-17 ; Palevicius, A ; Dashti, A ; Nasiri, S ; Monshi, A ; Vilkauskas, A ; Janusas, G ; Sharif University of Technology
MDPI AG
2020
Abstract
Young’s modulus (E) is one of the most important parameters in the mechanical properties of solid materials. Young’s modulus is proportional to the stress and strain values. There are several experimental and theoretical methods for gaining Young’s modulus values, such as stress–strain curves in compression and tensile tests, electromagnetic-acoustic resonance, ultrasonic pulse echo and density functional theory (DFT) in different basis sets. Apparently, preparing specimens for measuring Young’s modulus through the experimental methods is not convenient and it is time-consuming. In addition, for calculating Young’s modulus values by software, presumptions of data and structures are needed....
Densification and grain growth of nanocrystalline 3Y-TZP during two-step sintering
, Article Journal of the European Ceramic Society ; Volume 28, Issue 15 , 2008 , Pages 2933-2939 ; 09552219 (ISSN) ; Simchi, A ; Golestani Fard, F ; Sharif University of Technology
2008
Abstract
Two-step sintering (TSS) was applied on nanocrystalline yttria tetragonal stabilized zirconia (3Y-TZP) to control the grain growth during the final stage of sintering. The process involves firing at a high temperature (T1) followed by rapid cooling to a lower temperature (T2) and soaking for a prolonged time (t). It is shown that for nanocrystalline 3Y-TZP (27 nm) the optimum processing condition is T1 = 1300 °C, T2 = 1150 °C and t = 30 h. Firing at T1 for 1 min yields 0.83 fractional density and renders pores unstable, leading to further densification at the lower temperature (T2) without remarkable grain growth. Consequently, full density zirconia ceramic with an average grain size of 110...
Effect of Si content and heat treatment on microstructure and magnetic properties of mechanically alloyed Fe-Si powders
, Article Materials Science and Technology Conference and Exhibition, MS and T'07 - ""Exploring Structure, Processing, and Applications Across Multiple Materials Systems"", Detroit, MI, 16 September 2007 through 20 September 2007 ; Volume 4 , 2007 , Pages 2701-2712 ; 9781605601335 (ISBN) ; Abachi, P ; Madaah Hosseini, H. R ; Sharif University of Technology
2007
Abstract
In this study, the effects of milling time, chemical composition and heat treatment on microstructure and magnetic properties of nanocrystalline Fe-Si (6.5-25 at.% Si) alloys prepared by mechanical alloying have been investigated. The results show that increasing the milling time or the Si content, decreases the lattice parameter and increases the internal microstrain. The prepared powders mainly consist of micron-sized particles with an average grain size of less than 20 nm. The specific saturation magnetization values are slightly less than those of single crystal or conventional Fe-Si alloys and decrease as Si content increases. The coercive force values of the nanocrystalline as-milled...
Taguchi analysis of extrusion variables and composition effects on the morphology and mechanical properties of EPR-g-MA toughened polyamide 6 and its composite with short glass fiber
, Article Materials Science and Engineering A ; Volume 506, Issue 1-2 , 2009 , Pages 45-57 ; 09215093 (ISSN) ; Fereydoon, M ; Sharif University of Technology
2009
Abstract
Various compositions of maleated ethylene-propylene-rubber (EPR-g-MA) toughened polyamide 6 without and with short glass fiber, i.e. 5-20 wt.% rubber and 5-20 wt.% fiber, are prepared using an industrial twin-screw extruder at different levels of feed rate (100-250 kg/h), screw speed (200-450 rpm) and barrel temperature (230-260 °C). Trial runs designed based on the Taguchi's orthogonal arrays are subjected to tensile, impact, scanning electron microscopy (SEM) and optical microscopy tests; and the results are used to perform the analysis of variance (ANOVA). It is shown that the rubber particle size decreases significantly by increasing the rubber content for the unreinforced blend. The...
Kinetics investigation of the photocatalytic degradation of acid blue 92 in aqueous solution using nanocrystalline TiO2 prepared in an ionic liquid
, Article Progress in Reaction Kinetics and Mechanism ; Volume 34, Issue 1 , 2009 , Pages 55-76 ; 14686783 (ISSN) ; Rahimnejad, S ; Rahman Setayesh, S ; Hosseini, M ; Gholami, M. R ; Sharif University of Technology
2009
Abstract
TiO2 nanoparticles were prepared by the sol - gel process using 2-hydroxylethy- lammonium formate as an ionic liquid. Nanoparticles were crystallized at various temperatures (300-700°C). The products were characterized using X-ray diffraction (XRD), nitrogen adsorption - desorption isotherms and scanning electron microscopy (SEM) techniques. It was found that the resulting TiO2 nanoparticles had good thermal stability either to resist collapse or the anatase-to-rutile phase transformation during heat treatment. The photocatalytic activity of the nanocrystalline TiO2 was evaluated by the degradation of Acid Blue 92 (AB92) which is commonly used as a textile dye. The results showed that the...
Low-temperature perovskite-type cadmium titanate thin films derived from a simple particulate sol-gel process
, Article Acta Materialia ; Volume 57, Issue 4 , 2009 , Pages 1049-1059 ; 13596454 (ISSN) ; Fray, D. J ; Sharif University of Technology
2009
Abstract
Low-temperature perovskite-type cadmium titanate (CdTiO3) with a nanocrystalline and mesoporous structure was prepared at various Ti:Cd molar ratios by a straightforward particulate sol-gel route. The prepared sols had a narrow particle size distribution, in the range 23-26 nm. X-ray diffraction and Fourier transform infrared spectroscopy revealed that the powders contained a mixture of ilmenite-CdTiO3, perovskite-CdTiO3, anatase and rutile phases, depending on the annealing temperature and the Ti:Cd molar ratio. Perovskite-CdTiO3 was the major type obtained from cadmium-prominent powders at low temperature, whereas ilmenite-CdTiO3 was the major type obtained from titanium-prominent powders...