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Boehmite nanopetals self assembled to form rosette-like nanostructures
, Article Materials Letters ; Volume 62, Issue 26 , 2008 , Pages 4184-4186 ; 0167577X (ISSN) ; Attarchi, M ; Lak, A ; Mohajerani, M. S ; Kajbafvala, A ; Zanganeh, S ; Sadrnezhaad, S. K ; Sharif University of Technology
2008
Abstract
Rosette-like boehmite nanostructures were prepared successfully via a simple hydrothermal process. The obtained material was characterized with X-ray powder diffractometry (XRD), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Using Scherrer formula, the average crystallite size of the obtained boehmite rosettes was measured to be about 8 nm. It was shown that boehmite nanopetals with average width of about 41 nm determined by TEM, were formed during the hydrothermal process and then self assembled due to weak hydrogen bonds to fabricate boehmite rosettes. The specific surface area of the obtained rosette-like nanostructures was calculated through BET...
Characterization of yittria stabilized zirconia/titania core-shell powders synthesized via air plasma spray method
, Article Materials Chemistry and Physics ; Volume 200 , 2017 , Pages 280-286 ; 02540584 (ISSN) ; Rahimipour, M. R ; Vaezi, M. R ; Gholamzadeh, A ; Sharif University of Technology
Abstract
In this study, Yittria Stabilized Zirconia/Titania powders synthesized via air plasma spray (APS) method such as morphology changes and phase transformations of core-shell structure characterized. Phase analysis of powders was performed by XRD. The crystallite size and lattice strain of YSZ/TiO2 core-shell structure was calculated by Williamson-Hall method. Morphology was observed with scanning electron microscope. EDS and map analysis were used for core-shell characterization. Results revealed that all TiO2 nano particles were melted around YSZ powders with the thickness between 1 up to 5 μm. After spraying the YSZ/TiO2 mixture in water, strain values increased but crystallite size...
Synergetic effect of Ni and Nb2O5 on dehydrogenation properties of nanostructured MgH2 synthesized by high-energy mechanical alloying
, Article International Journal of Hydrogen Energy ; Volume 34, Issue 18 , 2009 , Pages 7724-7730 ; 03603199 (ISSN) ; Kaflou, A ; Simchi, A ; Sharif University of Technology
2009
Abstract
Nanostructured MgH2-Ni/Nb2O5 nanocomposite was synthesized by high-energy mechanical alloying. The effect of MgH2 structure, i.e. crystallite size and lattice strain, and the presence of 0.5 mol% Ni and Nb2O5 on the hydrogen-desorption kinetics was investigated. It is shown that the dehydrogenation temperature of MgH2 decreases from 426 °C to 327 °C after 4 h mechanical alloying. Here, the average crystallite size and accumulated lattice strain are 20 nm and 0.9%, respectively. Further improvement in the hydrogen desorption is attained in the presence of Ni and Nb2O5, i.e. the dehydrogenation temperature of MgH2/Ni and MgH2/Nb2O5 is measured to be 230 °C and 220 °C, respectively. Meanwhile,...
Effect of brookite presence on nanocrystalline anatase - Rutile phase transformation
, Article International Journal of Nanotechnology ; Volume 6, Issue 10-11 , 2009 , Pages 961-972 ; 14757435 (ISSN) ; Askari, M ; Sasani Ghamsari, M ; Sharif University of Technology
2009
Abstract
TiO2nanocrystals were prepared by hydrolysis and peptisation of titanium isopropoxide under different pH values. The as-prepared powder of very fine anatase crystallites ranges from 8 nm in acidic solution of pH 3 to 10 nm in basic solution of pH 8. Heat treatment of the powders leads to grain growth and anatase - rutile transformation. Experimental results have shown that the anatase to rutile phase transformation in the heat-treated powders depend not only on primary crystallite size but also the presence of brookite phase. It is observed that in the powders with the same size the presence brookite phase would accelerate the anatase to rutile transformation. Furthermore it has been found...
The relation between particle size and transformation temperature of gibbsite to αLPHA-alumina
, Article Mineral Processing and Extractive Metallurgy: Transactions of the Institute of Mining and Metallurgy ; 2020 ; Nemati, A ; Arzani, K ; Baghshahi, S ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
The transformation of gibbsite to α-alumina occurs in the range 1100 to 1300°C. The higher the calcination temperature, the larger the crystallites and this leads to abnormal grain growth. The main goal of this research was to reduce the transformation temperature of gibbsite to α-alumina by reducing the gibbsite particles size. The sodium content of the gibbsite used in the study was reduced to less than 0.1% by washing it in HCl solution. It was then ground in a fast mill at ambient conditions for different times then calcined at different temperatures. The microstructure, particles size and thermal behaviour of the samples were examined with SEM, XRD, XRF, PSA and STA, respectively. In a...
Surface severe plastically deformed nanostructured aa7075 alloy: assessment on tribological and axial fatigue behaviors
, Article Journal of Materials Engineering and Performance ; Volume 29, Issue 6 , 2020 , Pages 3774-3783 ; Karademir, I ; Husem, F ; Maleki, E ; Unal, O ; Sharif University of Technology
Springer
2020
Abstract
AA7075 alloy is exposed to severe shot peening (SSP) with an Almen intensity of 20A. The microstructure is analyzed via FEGSEM and EBSD microscopy. X-ray diffraction (XRD) analysis is used to evaluate the crystallite size in terms of FWHM measurements. The residual stress measurements show a thicker compressed layer (600 µm) formed by SSP. Microhardness improvements are observed as 30% on topmost surface and releases substantially after 600 µm. Coefficient of friction (COF) of treated material remains higher throughout the sliding distance, however, is reduced particularly in the early stage of sliding distance for the wear load of 20 N. The effect of SSP is vanished particularly at lower...
Artificial neural network modeling of mechanical alloying process for synthesizing of metal matrix nanocomposite powders
, Article Materials Science and Engineering A ; Volume 466, Issue 1-2 , 2007 , Pages 274-283 ; 09215093 (ISSN) ; Shokuhfar, A ; Simchi, A ; Sharif University of Technology
2007
Abstract
An artificial neural network model was developed for modeling of the effects of mechanical alloying parameters including milling time, milling speed and ball to powder weight ratio on the characteristics of Al-8 vol%SiC nanocomposite powders. The crystallite size and lattice strain of the aluminum matrix were considered for modeling. This nanostructured nanocomposite powder was synthesized by utilizing planetary high energy ball mill and the required data for training were collected from the experimental results. The characteristics of the particles were determined by X-ray diffraction, scanning and transmission electron microscopy. Two types of neural network architecture, i.e. multi-layer...
Nickel-doped monoclinic WO3 as high performance anode material for rechargeable lithium ion battery
, Article Journal of Electroanalytical Chemistry ; Volume 894 , 2021 ; 15726657 (ISSN) ; Javanbakht, M ; Omidvar, H ; Hooshyari, K ; Salarizadeh, P ; Askari, M. B ; Sharif University of Technology
Elsevier B.V
2021
Abstract
The anode materials are one of the critical components in rechargeable lithium ion batteries (LIBs). The monoclinic tungsten trioxide (mWO3) is introduced as interesting anode electrode for LIBs due to its good structure for intercalation and de-intercalation of lithium ions, high abundance and various oxidation state of tungsten and etc. In this study, we prepare and investigate the effect of various amounts of nickel dopant on characteristics and electrochemical properties of the mWO3 as the anode electrode in a rechargeable LIB. The experimental investigations confirm that the number of nickel atoms has a remarkable effect on controlling spherical particle diameter, crystallite size, and...
Metal–organic frameworks (MOFs) for cancer therapy
, Article Materials ; Volume 14, Issue 23 , 2021 ; 19961944 (ISSN) ; Rabiee, N ; Mozafari, M ; Verpoort, F ; Voskressensky, L. G ; Luque, R ; Sharif University of Technology
MDPI
2021
Abstract
MOFs exhibit inherent extraordinary features for diverse applications ranging from cataly-sis, storage, and optics to chemosensory and biomedical science and technology. Several procedures including solvothermal, hydrothermal, mechanochemical, electrochemical, and ultrasound techniques have been used to synthesize MOFs with tailored features. A continued attempt has also been directed towards functionalizing MOFs via “post-synthetic modification” mainly by changing linkers (by altering the type, length, functionality, and charge of the linkers) or node components within the MOF framework. Additionally, efforts are aimed towards manipulating the size and morphology of crystallite domains in...
Impact of holmium on structural, dielectric and magnetic properties of Cu–Zn spinel ferrites synthesized via sol–gel route
, Article Journal of Materials Science: Materials in Electronics ; Volume 32, Issue 2 , 2021 , Pages 2205-2218 ; 09574522 (ISSN) ; Khan, M. A ; Hussain, A ; Akhtar, M. N ; Ahmad, M ; Javid, M. A ; Sharif University of Technology
Springer
2021
Abstract
The mixed nano-ferrites materials Cu0.6Zn0.4HoxFe2−xO4 (0.00 ≤ x ≤ 0.12) were prepared via the sol–gel auto combustion technique. The TGA curve established the annealing temperature (500 °C) for phase formation. The single exothermic peak on the DSC plot occurred at 341 °C temperature. XRD patterns of these nano ferrites verified single phase formation of the FCC cubic structure. The lattice constant a was increased from 8.4244 to 8.4419 Å and then its value decreased to 8.4319 Å. Crystallite size was found in the range of 7 to 16 nm. The surface morphology of the samples was observed from the scanning electron microscope (SEM) images. The grain size was found within the range of 90 nm to...
Impact of holmium on structural, dielectric and magnetic properties of Cu–Zn spinel ferrites synthesized via sol–gel route
, Article Journal of Materials Science: Materials in Electronics ; Volume 32, Issue 2 , 2021 , Pages 2205-2218 ; 09574522 (ISSN) ; Khan, M. A ; Hussain, A ; Akhtar, M. N ; Ahmad, M ; Javid, M. A ; Sharif University of Technology
Springer
2021
Abstract
The mixed nano-ferrites materials Cu0.6Zn0.4HoxFe2−xO4 (0.00 ≤ x ≤ 0.12) were prepared via the sol–gel auto combustion technique. The TGA curve established the annealing temperature (500 °C) for phase formation. The single exothermic peak on the DSC plot occurred at 341 °C temperature. XRD patterns of these nano ferrites verified single phase formation of the FCC cubic structure. The lattice constant a was increased from 8.4244 to 8.4419 Å and then its value decreased to 8.4319 Å. Crystallite size was found in the range of 7 to 16 nm. The surface morphology of the samples was observed from the scanning electron microscope (SEM) images. The grain size was found within the range of 90 nm to...
Structural, spectral, dielectric, and magnetic properties of indium substituted Cu0.5Zn0.5Fe2−xO4 magnetic oxides
, Article Journal of Materials Science: Materials in Electronics ; 2021 ; 09574522 (ISSN) ; Khan, M. A ; Al Muhimeed, T. I ; AlObaid, A. A ; Nazir, G ; Alshahrani, T ; Mahmood, Q ; Akhtar, M. N ; Sharif University of Technology
Springer
2021
Abstract
The influence of indium on the properties of Cu0.5Zn0.5Fe2O4 nano ferrites synthesized by sol–gel auto-combustion technique was studied. X-ray diffraction (XRD) analysis demonstrated that pure and substituted ferrites possessed cubic spinel structure. The lattice parameter increases with the inclusion of In3+ for x ≤ 0.16 and decreases subsequently. A linear decrease in crystallite size was found as concentration of indium increased. X-ray density, strain, and dislocation density were increased as indium content increases. Hopping lengths as well as radii of A and B sites revealed increasing behavior up to x = 0.16 and decreased thereafter. The spectral bands indicated the formation of...
Preparation of nanocrystalline Fe-Si-Ni soft magnetic powders by mechanical alloying
, Article Materials Science and Engineering B: Solid-State Materials for Advanced Technology ; Volume 123, Issue 1 , 2005 , Pages 74-79 ; 09215107 (ISSN) ; Bahrami, A ; Sharif University of Technology
2005
Abstract
In this study, structural and magnetic properties of nanocrystalline Fe-Si-Ni powders produced by mechanical alloying (MA) have been investigated. The samples with different chemical compositions and milling times were characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The alloy powders with average grain size 8-19 nm were synthesized by milling for 35-100 h. Coercivity (Hc) and crystallite size exhibited a similar decrease by increasing the mechanical alloying time. Maximum saturation magnetization (Ms) and minimum Hc were obtained at the composition of Fe87Si10Ni5 after 70 h milling. © 2005 Elsevier B.V. All rights reserved
Mechanical induced reaction in Al-CuO system for in-situ fabrication of Al based nanocomposites
, Article Journal of Alloys and Compounds ; Volume 465, Issue 1-2 , 2008 , Pages 151-156 ; 09258388 (ISSN) ; Simchi, A ; Seyed Reihani, S. M ; Sharif University of Technology
2008
Abstract
Gradual chemical (displacement) reaction between CuO and Al powders during high-energy attrition milling under a high purity argon atmosphere was studied. Differential thermal analysis (DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques were employed to study the solid-state reaction. It was shown that the solid-state reaction occurred during mechanical alloying (MA) and resulted in the dissolution of copper into the aluminum lattice and formation of nanometric alumina particles. The reinforcement particles were mostly distributed at the grain boundaries of Al matrix with an average crystallite size of about 50 nm. In DTA curve of the milled powders, a small...
Application of the statistical Taguchi method to optimize TiO2 nanoparticles synthesis by the hydrothermal assisted sol-gel technique
, Article Ceramics International ; Vol. 40, Issue 3 , 2014 , pp. 4193-4201 ; ISSN: 02728842 ; Faghihi Sani, M. A ; Madaah Hosseini, H. R ; Sharif University of Technology
Abstract
TiO2 nanoparticles were synthesized by hydrothermal assisted sol-gel technique. The preparation parameters including pH value, the amount of water, titanium tetra isopropoxide content, temperature and time of hydrothermal process were investigated by Taguchi statistical experiments to determine the influence of synthesizing variables on the optimal conditions and to realize the highest degree of crystallinity or smallest crystallite size. X-ray diffraction (XRD) analysis and direct band gap energy (Eg) values, measured via diffuse reflectance spectra (DRS), proved that all the samples consist of anatase as a unique phase. Transmission electron microscopy (TEM) and specific surface area...
Synthesis and characterization of co-doped TiO2 thin films on glass-ceramic
, Article Materials Science in Semiconductor Processing ; Vol. 26, Issue 1 , October , 2014 , pp. 41-48 ; ISSN: 13698001 ; Nemati, A ; Solati-Hashjin, M ; Sharif University of Technology
Abstract
In this research, an attempt was made to improve TiO2 photo-catalyst properties, thus pure, N-Ce co-doped TiO2 thin films were prepared on glass-ceramic substrate using a sol-gel dip-coating technique. The samples were calcinated in air at 475 °C, 550°C, and 650°C for 2 h. The result of simultaneous thermal analysis (STA) and X-ray diffraction (XRD) showed that the presence of Ce in TiO2 could inhibit the phase transformation from anatase to rutile and enhance the thermal stability, and anatase was the dominant phase in N-Ce co-doped TiO2 samples. Also based on the results, the doping results in decreasing the size of TiO 2 crystallite. The results of ultra violet-visible light diffuse...
Synthesis of nanocrystalline Ni/Ce-YSZ powder via a polymerization route
, Article Materials Science- Poland ; Volume 31, Issue 3 , 2013 , Pages 343-349 ; 01371339 (ISSN) ; Tamizifar, M ; Arzani, K ; Nemati, A ; Khanfekr, A ; Bolandi, M ; Sharif University of Technology
Oficyna Wydawnicza Politechniki Wroclawskiej
2013
Abstract
Pechini process was used for preparation of three kinds of nanocrystalline powders of yttria-stabilized zirconia (YSZ): doped with 1.5 mol% nickel oxide, doped with 15 mol% ceria, and doped with 1.5 mol% nickel oxide plus 15 mol% ceria. Zirconium chloride, yttrium nitrate, cerium nitrate, nickel nitrate, citric acid and ethylene glycol were polymerized at 80 °C to produce a gel. XRD, SEM and TEM analyses were used to investigate the crystalline phases and microstructures of obtained compounds. The results of XRD revealed the formation of nanocrystalline powder at 900 °C. Morphology of the powder calcined at 900 °C, examined with a scanning electron microscope, showed that the presence of...
Structural characteristics and desorption properties of nanostructured MgH2 synthesised by high energy mechanical milling
, Article Powder Metallurgy ; Volume 54, Issue 4 , 2011 , Pages 480-483 ; 00325899 (ISSN) ; Kaflou, A ; Simchi, A ; Sharif University of Technology
2011
Abstract
The effect of particle size, lattice strain and crystallite size on the hydrogen desorption properties of nanocrystalline magnesium hydride powder was investigated. Commercial MgH2 powder was milled in a Spex 8000M up to 16 h and its structural evolution and desorption characteristics at different time intervals were examined using various analytical techniques. At the early stage of milling, the formation of metastable γ-MgH2 phase was noticed. While the crystallite size gradually decreased to 12 nm with increasing the milling time, the accumulated lattice strain gained a maximum value of 0·9% after 4 h milling. The highest drop in the desorption temperature (∼100°C) was attained at the...
Electrophoretic deposition and sintering of a nanostructured manganese-cobalt spinel coating for solid oxide fuel cell interconnects
, Article Ceramics International ; Volume 42, Issue 6 , May , 2016 , Pages 6648–6656 ; 02728842 (ISSN) ; Simchi, A ; Faghihi Sani, M. A ; Yazdanyar, A ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
Solid oxide fuel cell (SOFC) is one of the promising candidates for clean energy production. Due to the high operating temperature of SOFCs, a protective coating is commonly applied on the surface of interconnects to prevent oxidation. In this study, electrophoretic deposition was employed to prepare a manganese-cobalt spinel coating on ferritic stainless steel (AISISAE430) substrates. Nanostructured MnCo2O4 powder with an average crystallite size of 60nm was utilized and the sintering behavior of the coatings at different temperatures was studied. Non-isothermal and isothermal sintering behavior of the powder were examined by employing a sensitive dilatometer. Master sintering curve of the...
Facile synthesis of NiTiO3 yellow nano-pigments with enhanced solar radiation reflection efficiency by an innovative one-step method at low temperature
,
Article
Dyes and Pigments
;
Volume 123
,
2015
,
Pages 92-99
;
01437208 (ISSN)
; Shahrouzianfar, A
; Ashiri, R
;
Sharif University of Technology
Elsevier Ltd
2015
Abstract
Abstract Inorganic NiTiO3 nano-pigments have received recent attentions as possible candidates for cool pigment materials to be used in building roofs and facades. In this paper, we have attempted to develop an innovative low temperature (50 °C) synthesis pathway for obtaining NiTiO3 nanocrystals based on an ultrasound-assisted wet chemical processing method. The crystallite size, average particle size and band gap are found to be 11 nm, in the range of 10-20 nm and 3.72 eV, respectively. Ultraviolet-visible (UV-vis) reflectance spectra show that NiTiO3 nanoparticles have a high reflection peak at ∼580 nm, which is associated with the brilliant yellow color...