Search for: rare-earths
Total 42 records
Solvent extraction of rare earth elements from a nitric acid leach solution of apatite by mixtures of tributyl phosphate and di-(2-ethylhexyl) phosphoric acid, Article Metallurgical and Materials Transactions B: Process Metallurgy and Materials Processing Science ; Volume 48, Issue 6 , 2017 , Pages 3380-3387 ; 10735615 (ISSN) ; Yoozbashizadeh, H ; Sharif University of Technology
Solvent extraction of rare earths from nitrate leach liquor of apatite using mixtures of tributyl phosphate (TBP) and di-(2-ethylhexyl) phosphoric acid (D2EHPA) was studied. The effects of nitrate and hydrogen ion concentration of the aqueous phase as well as the composition and concentration of extractants in the organic phase on the extraction behavior of lanthanum, cerium, neodymium, and yttrium were investigated. The distribution ratio of REEs increases by increasing the nitrate concentration in aqueous phase and concentration of extractants in organic phase, but the hydrogen ion concentration in aqueous phase has a decreasing effect. Yttrium as a heavy rare earth is more sensitive to...
Effect of rare-earth element additions on high-temperature mechanical properties of AZ91 magnesium alloy, Article Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science ; Volume 36, Issue 12 , 2005 , Pages 3489-3494 ; 10735623 (ISSN) ; Nami, B ; Khoshkhooei, S ; Sharif University of Technology
Minerals, Metals and Materials Society 2005
The present article focuses on the high-temperature mechanical properties of the magnesium alloy AZ91. The addition of rare-earth (RE) elements up to 2 wt pct improves both yield and tensile strengths at 140 °C by replacing the Mg17Al12 phase with RE-containing intermetallic compounds. This intermetallic phase is thermally and metallurgically stable and is expected to boost the grain-boundary strengthening. It also increases the resistance of grain boundaries to flow at high temperatures. Further increases of RE additions reduce strength and ductility due to growth of the Al11RE3 brittle phase, which has sharp edges. Still, at a 3 wt pct RE addition, the strength of the alloy at high...
Article ChemPhysChem ; Volume 18, Issue 23 , 2017 , Pages 3292-3308 ; 14394235 (ISSN) ; Taghavinia, N ; Wei Guang Diau, E ; Sharif University of Technology
Relative to the broadband solar spectrum, a narrow range of spectral absorption of photovoltaic (PV) devices is considered an important determinant that the efficiency of light harvesting of these devices is less than unity. Having the narrowest spectral response to solar radiation among all PV devices, dye-sensitized solar cells (DSSCs) suffer severely from this loss. Luminescent spectral conversion provides a mechanism to manipulate and to adapt the incident solar spectrum by converting, through photoluminescence, the energies of solar photons into those that are more effectively captured by a PV device. This mechanism is particularly helpful for DSSCs because there is much flexibility in...
Article Magnesium Technology 2009, San Francisco, CA, 15 February 2009 through 19 February 2009 ; 2009 , Pages 483-488 ; 15454150 (ISSN); 9780873397308 (ISBN) ; Khomamizadeh, F ; Magnesium Committee of the Light Metals Division; Minerals, Metals and Materials Society, TMS ; Sharif University of Technology
This paper focuses on creep properties of AZ91-RE and heat treated AZ91 magnesium alloy. Influence of heat treatment and rare earths addition on microstructure and mechanical properties were investigated. Creep behavior is dependent on the stability of the near grain boundary microstructure and is improved by rare earth addition. The results show that sliding of grain boundaries has an important part in the deformation mechanism in AZ91 alloy at elevated temperatures which is greatly suppressed by the rare earths addition
Article Sensors and Actuators B: Chemical ; Volume 348 , 2021 ; 09254005 (ISSN) ; Legin, E ; Legin, A ; Yaghmaei, S ; Nechaev, A ; Babain, V ; Kirsanov, D ; Sharif University of Technology
Elsevier B.V 2021
Scandium is a rare earth element that is not very abundant on Earth, however in recent years due to the employment of scandium in various high-tech fields the interest in the analytical chemistry of this metal is growing. Currently, the methods for scandium quantification are mainly based on inductively coupled plasma atomic emission and mass-spectrometry and to the best of our knowledge no potentiometric sensors for scandium detection were reported so far. This study is devoted to the development of simple and cost-effective ion-selective sensors for quantification of Sc3+ in aqueous media. Employing the variety of lipophilic ligands suggested in liquid extraction for separation of...
Article Minerals and Metallurgical Processing ; Volume 30, Issue 1 , February , 2013 , Pages 53-58 ; 07479182 (ISSN) ; Yoozbashizadeh, H ; Mohammadi, M ; Abazarpoor, A ; Maarefvand, M ; Sharif University of Technology
Molybdenum resources around the world are mainly associated with porphyry copper ores. Molybdenite (MoS2) is the main Mo mineral that has rhenium in its crystal lattice. This paper investigates the recovery of rhenium and molybdenum from a molybdenite concentrate using a hydrometallurgical treatment method. The molybdenite concentrate is leached with nitric acid and subjected to solvent extraction to recover and separate rhenium and molybdenum from the leached liquor. The effects of pH and the chemicals' concentration on extraction characteristics of Mo and Re are investigated to define the best condition for selective extraction of these metals. The tested leached liquor contained of 8.2...
Article Laser Physics ; Volume 28, Issue 4 , March , 2018 ; 1054660X (ISSN) ; Rooholamininejad, H ; Bahrampour, A ; Sharif University of Technology
Institute of Physics Publishing 2018
In this work, the generation of two-soliton and three-soliton molecules in a circular fiber array laser with an active optical central fiber is studied. Certain fibers of the array are excited by Gaussian and super-Gaussian pulses. The central fiber of the circular fiber laser is a rare-earth doped fiber. A circular fiber array is employed as a saturable absorber in a soliton mode locked fiber laser. Generation of two-soliton and three-soliton molecules are observed in our simulation. Numerical calculation of binding energy shows that the super-Gaussian pulse tends to be more stable, and therefore it would be a proper choice for the generation of soliton molecules in the circular fiber array...
Process optimization and kinetics for leaching of cerium, lanthanum and neodymium elements from iron ore waste's apatite by nitric acid, Article Transactions of Nonferrous Metals Society of China (English Edition) ; Volume 27, Issue 2 , 2017 , Pages 420-428 ; 10036326 (ISSN) ; Yoozbashizadeh, H ; Sharif University of Technology
Nonferrous Metals Society of China 2017
The leaching of rare earth elements (REEs) including cerium, lanthanum and neodymium from apatite concentrate obtained from iron ore wastes by nitric acid was studied. The effects of nitric acid concentration, solid to liquid ratio and leaching time on the recoveries of Ce, La and Nd were investigated using response surface methodology. The results showed that the acid concentration and solid to liquid ratio have significant effect on the leaching recoveries while the time has a little effect. The maximum REE leaching recoveries of 66.1%, 56.8% and 51.7% for Ce, La and Nd, respectively were achieved at the optimum leaching condition with 18% nitric acid concentration, 0.06 solid to liquid...
Geochemical characteristics of rare earth elements in different types of soil: a chemometric approach, Article Chemosphere ; Volume 184 , 2017 , Pages 673-678 ; 00456535 (ISSN) ; Behkami, S ; Yusoff, I ; Md Zain, S. B ; Bakar, N. K. A ; Bakar, A. F. A ; Alias, Y ; Sharif University of Technology
Rare earth elements (REEs) are becoming significant due to their huge applications in many industries, large-scale mining and refining activities. Increasing usage of such metals pose negative environmental impacts. In this research ICP-MS has been used to analyze soil samples collected from former ex-mining areas in the depths of 0–20 cm, 21–40 cm, and 41–60 cm of residential, mining, natural, and industrial areas of Perak. Principal component analysis (PCA) revealed that soil samples taken from different mining, industrial, residential, and natural areas are separated into four clusters. It was observed that REEs were abundant in most of the samples from mining areas. Concentration of the...
M.Sc. Thesis Sharif University of Technology ; Maddah Hosseini, Hamid Reza ; Mohammadi, Mohammad Reza
Photodynamic therapy that has developed over last century, now has become more widely used medical tool for the treatment of various diseases such as cancer. This technique involves delivery of photosensitizing drugs, irradiation of light and motivation of drugs. The limitation of light penetration in body tissue, may resolve by application of upconversion nanoparticles. Upconverting nanoparticles could help treatment of cancer tumors in deep or critical points of body by converting high penetrating Near-Infrared emissions to higher energy visible emissions.In this research Er3+-Yb3+ Co-doped titanium dioxide upconversion nanoparticles prepared by Sol-gel method. The phase structure and...
M.Sc. Thesis Sharif University of Technology ; Maddah Hosseini, Hamid Reza
Photodynamic therapy that has been developed over last century, now has become more widely used medical tool for the treatment of various diseases such as cancer. This technique involves delivery of photosensitizing drugs, irradiation of light and motivation of drugs. The limitation of light penetration in body tissue, may resolve by application of upconversion nanoparticles. Upconverting nanoparticles could help treatment of cancer tumors in deep or critical points of body by converting high penetrating Near-Infrared emissions to higher energy visible emissions. In the present work, rare earth elements doped TiO2 nanoparticles are synthesized. The photodynamic properties of rare earth...
Apatite Digestion and Two-step Leaching in Concentrate Sulfuric Acid for Recovery of REEs’ Cerium, Lanthanum, Neodymium and Yttrium, M.Sc. Thesis Sharif University of Technology ; Yoozbashizadeh, Hossein
Nowadays, apatite mineral is one of the most sought for the recovery of rare earth elements. This mineral is also the main source of phosphoric acid production. To achieve this end, apatite has to react with sulfuric acid to give phosphoric acid. This process is called the wet process. During the wet process, more rare elements enter the remaining solids called phosphogypsum (PG). For the dissolution of rare elements, PG, which is the same as chalk, can be leach with an acidic solution. In this project, the phosphate concentrate from Chadormalu iron ore waste after characteristics diagnosis is digested in concentrated sulfuric acid at temperatures below 100 ° C, and then hydration is...
an Investigation on REEs' Cerium, Lanthanum, Neodymium leaching from Phosphate Concentrate of Iron Ore Waste in Acidic Environment and Studing Purification and Concentration of the Solution, M.Sc. Thesis Sharif University of Technology ; Yoozbashizadeh, Hossein
The term “Rare Earth”, represents 17 metalic elements such as Sc, Y and Lanthanides wich have similar chemical properties. Lanthanides are a group of elements with atomic numbers of 57 to 71 that all of them exept Pm are present in nature. Rare earth elements are never concentrated in a special mine rock, but they could be found in various rocks and at very low concentrations. In the present study, apatite concentrate of Chadormalu was used for leaching and solvent extraction of Cerium, Lanthanum and Neodymium. After leaching step, its optimum conditions were found as follow: 30% nitric acid, 10 mins time and 10% for solid to liquid ratio. After finding optimum conditions, sufficient leach...
Modification of Three-Way Catalyst (Twc)Formulation for Gasoline Vehicles with the Goal of Improving Its Thermal Stability, M.Sc. Thesis Sharif University of Technology ; Hamzehlouyan, Tayebeh
Vehicle exhaust gas catalysts play a significant role in air pollution control. In order to solve the problems of cold start and limited supply of precious metals, new studies have focused on the development of three-way catalysts for gasoline vehicles with small amounts of precious metals and increase thermal stability. Different metal ions, especially rare earth metals, due to different physical and chemical properties, show different reinforcing effects on the properties of ceria-zirconia-based materials. Previous studies have shown that the enhancing effect of these materials and the ceria-zirconia ratio on catalyst activity and stability, as well as studies on thermal stability at 1050...
The effect of different rare earth elements content on microstructure, mechanical and wear behavior of Mg-Al-Zn alloy, Article Materials Science and Engineering A ; Volume 527, Issue 7-8 , 2010 , Pages 2027-2035 ; 09215093 (ISSN) ; Masoudi, A ; Khomamizadeh, F ; Sharif University of Technology
The effect of Rare earths addition to AZ91 magnesium alloy and its influence on the microstructure and mechanical properties was investigated in this study. Addition of cerium rich misch metal to AZ91 alloy resulted in formation of needle shape particles, which had a very high thermal stability, providing superior mechanical properties compared to AZ91 magnesium alloy. As a result, the grain boundaries were less susceptible for grain boundary sliding at high temperatures. The steady state creep rates were specified and for the AZ91 alloy and the results indicate a mixed mode of creep behavior, with some grain boundary effects contributing to the overall behavior. However for the RE added...
The effects of MM38.2Co46.4Ni15.4 alloy additions on the mechanical properties of a Nd12.8Fe 79.8B7.4-type sintered magnet, Article Materials Letters ; Volume 60, Issue 4 , 2006 , Pages 555-558 ; 0167577X (ISSN) ; Kianvash, A ; Sharif University of Technology
The mechanical properties of the Nd-Fe-B-based alloys are closely related to their microstructures. It was found that the Co and Ni additions to the Nd2Fe14B (Φ) matrix phase and reduction in the amounts of rare earth (RE)-rich (n) and B-rich (η) grain boundary phases are very effective in improving the mechanical properties. The addition of a MM 38.1(MM: Misch Metal)-Co46.4-Ni15.5 alloy to a ternary Nd12.8Fe79.8B7.4-type alloy by a binary powder blending technique resulted in a considerable increase in bending and compressive strength, and a significant decrease in impact strength. The solid solution hardening of the matrix phase by Co and Ni and the presence of intergranular cracks within...
Article Materials Science and Engineering A ; Volume 588 , December , 2013 , Pages 357-365 ; 09215093 (ISSN) ; Azadi, M ; Hossein Farrahi, G ; Winter, G ; Eichlseder, W ; Sharif University of Technology
In the present paper, an improvement in high temperature fatigue properties of the AZ91 magnesium alloy with rare earth elements has been obtained by a typical heat treatment, denoted by T6. For this objective, out-of-phase thermo-mechanical fatigue, room temperature and high temperature low cycle fatigue tests are performed to compare lifetimes. Several rare earth elements are initially added to the AZ91 alloy during a gravity casting process in permanent molds. Also, the type of the heat treatment is examined. Results of specimens with only the solution (the T4 heat treatment) and the solution with the ageing process (the T6 heat treatment) are compared under isothermal fatigue loadings....
Article Journal of Alloys and Compounds ; Volume 509, Issue 5 , February , 2011 , Pages 1567-1572 ; 09258388 (ISSN) ; Khomamizadeh, F ; Sharif University of Technology
In the present article, the effect of Rare Earth elements on the microstructural development of as cast and semisolid Mg-4Al alloy produced by SIMA process is studied. Investigation conducted by metallographic observation, scanning electron microscope and quantitative metallographic methods. Results showed that alloy's dendrites turn into larger fully dendritic shape with sharp and narrow arms from equiaxed rosette type as the amount of RE elements increased from 0 through 4%. The effect of RE elements on the microstructure of the treated-alloys was detectable through elimination of vast number of intragranular liquid droplets as well as by decreasing kinetic of microstructural changes. It...
Article Journal of Rare Earths ; Volume 27, Issue 2 , 2009 , Pages 255-258 ; 10020721 (ISSN) ; Saebnoori, E ; Sharif University of Technology
Chinese Society of Rare Earths 2009
Influences of rare earth (RE) elements addition on thermal fatigue behaviors of AZ91 alloy were studied. Repeated heating and cooling cycles were applied on the samples at 170 and 210 °C to develop thermal fatigue cracks. Crack growth mechanisms and microstructural influences were investigated by optical and scanning electron microscopy (SEM) as well as energy dispersive X-ray spectroscopy (EDS). Thermal fatigue behaviors were observed to improve successively by addition of the RE up to 2wt.%. This improvement was attributed to the consummation of aluminum in melt by precipitation of the needle shaped Al11RE3 phases. This process was attributed to the reduction of Mg17Al12 phase volume...
Effect of Gd and Co contents on the microstructural, magneto-optical and electrical characteristics of cobalt ferrite (CoFe2O4) nanoparticles, Article Ceramics International ; 2021 ; 02728842 (ISSN) ; Yousaf, M ; Akhtar, M. N ; Noor, A ; Akbar, M ; Shah, M. A. K. Y ; Yan, S ; Wang, F ; Sharif University of Technology
Elsevier Ltd 2021
Rare earth oxides with a trivalent nature play a pivotal role in reinforcing the magneto-optical attributes of spinel ferrite nanoparticles by replacing Fe3+ ions. In this study, rare earth Gd oxide doped with CoFe2O4 NPs with a composition of Co1+xGdxFe2-2xO4 (x = 0, 0.05, 0.10, and 0.15) were synthesized using sol-gel auto-combustion. The outcome of Gd cations on the physical, magneto-optical and electrical characteristics of the cobalt ferrite NPs were reported. X-ray diffraction (XRD), and Fourier transform infrared (FTIR) investigations confirmed the single-phase cubic crystalline nature and metal ion stretching in the cobalt ferrite synthesized samples. Decreasing drift in the average...