scholarly journals Effects of La2O3 Addition into CaO-SiO2 Slag: Structural Evolution and Impurity Separation from Si-Sn Alloy

2021 ◽  
Author(s):  
Mengyi Zhu ◽  
Guixuan Wu ◽  
Alexander Azarov ◽  
Eduard Monakhov ◽  
Kai Tang ◽  
...  
Keyword(s):  
Acid Leaching ◽  
Structural Evolution ◽  
Charge Compensation ◽  
Interaction Coefficient ◽  
Positive Interaction ◽  
Weak Charge ◽  
Slag Refining ◽  
Slag Chemistry ◽  
Slag Treatment ◽  
Dynamics Simulations

AbstractBoron (B) and phosphorus (P) are the most problematic impurities to be removed in the production of solar-grade silicon by the metallurgical process. In this work, the distribution of B and P between CaO-(La2O3)-SiO2 slags and Si-10 mass pct Sn melt was experimentally studied. B distribution coefficient increased from 2.93 in binary CaO-SiO2 slag to 3.33 and 3.65 with 2 and 10 mass pct La2O3 additions, respectively. In the followed acid-leaching experiments, the slag-treated Si-Sn alloys exhibited higher B and P removal than that of the initial alloy without slag treatment. Molecular dynamics simulations were performed to study the effect of La2O3 addition on the slag structural and transport properties. A novel oxygen classification method was proposed to distinguish the different structural roles of La and Ca in the CaO-La2O3-SiO2 system. It was found that La3+ prefers to stay in the depolymerized region, mostly connects with 6-7 non-bridging oxygen, and requires a weak charge compensation with Ca2+. Possible silicothermic reduction was evaluated to discuss the slag chemistry and the mass transfer between slag and metal phase. A thermodynamic model was derived to theoretically study the alloying effect on impurity distribution in slag refining where positive interaction coefficient and high alloying concentration were found most beneficial to improve the impurity removal.

Tunable Carbon Surface from Mono- to Multi-Metallic Single Atoms

2020 ◽  
Author(s):  
Weihong Lai ◽  
Heng Wang ◽  
Quan jiang ◽  
Zichao Yan ◽  
Hanwen Liu ◽  
...  
Keyword(s):  
Synergistic Effects ◽  
Structural Evolution ◽  
Charge Compensation ◽  
Catalytic Reactions ◽  
Single Atom ◽  
Carbon Surface ◽  
Hydrogen Electrode ◽  
Single Atoms ◽  
Mass Activity ◽  
Co Doped

<p>Herein, we develop a non-selective charge compensation strategy to prepare multi-single-atom doped carbon (MSAC) in which a sodium p-toluenesulfonate (PTS-Na) doped polypyrrole (S-PPy) polymer is designed to anchor discretionary mixtures of multiple metal cations, including iron (Fe<sup>3+</sup>), cobalt (Co<sup>3+</sup>), ruthenium (Ru<sup>3+</sup>), palladium (Pd<sup>2+</sup>), indium (In<sup>3+</sup>), iridium (Ir<sup>2+</sup>), and platinum (Pt<sup>2+</sup>) . As illustrated in Figure 1, the carbon surface can be tuned with different level of compositional complexities, including unary Pt<sub>1</sub>@NC, binary (MSAC-2, (PtFe)<sub>1</sub>@NC), ternary (MSAC-3, (PtFeIr)<sub>1</sub>@NC), quaternary (MSAC-4, (PtFeIrRu)<sub>1</sub>@NC), quinary (MSAC-5, (PtFeIrRuCo)<sub>1</sub>@NC), senary (MSAC-6, (PtFeIrRuCoPd)<sub>1</sub>@NC), and septenary (MSAC-7, (PtFeIrRuCoPdIn)<sub>1</sub>@NC) samples. The structural evolution of carbon surface dictates the activities of both ORR and HER. The senary MSAC-6 achieves the ORR mass activity of 18.1 A·mg<sub>metal</sub><sup>-1</sup> at 0.9 V (Vs reversible hydrogen electrode (RHE)) over 30K cycles, which is 164 times higher than that of commercial Pt/C. The quaternary MSAC-4 presented a comparable HER catalytic capability with that of Pt/C. These results indicate that the highly complexed carbon surface can enhance its ability over general electrochemical catalytic reactions. The mechanisms regarding of the ORR and HER activities of the alternated carbon surface are also theoretically and experimentally investigated in this work, showing that the synergistic effects amongst the co-doped atoms can activate or inactivate certain single-atom sites.</p>

Comparison between slag refining processes for B removal with metallurgical grade silicon and Si–Sn alloy

2018 ◽  
Vol 115 (3) ◽  
pp. 312 ◽  
Author(s):  
Rowaid Al-khazraji ◽  
Yaqiong Li ◽  
Lifeng Zhang
Keyword(s):  
Removal Efficiency ◽  
Acid Leaching ◽  
Experimental Results ◽  
Mass Ratio ◽  
Metallurgical Grade Silicon ◽  
Clear Effect ◽  
Slag Refining ◽  
Before And After ◽  
Grade Silicon ◽  
Refining Processes

Boron (B) removal by slag refining using CaO–SiO2–CaCl2 was investigated in metallurgical-grade silicon (MG-Si) and 75 wt% Si–Sn alloy. Experiments were conducted at 1500 °C for 15 min. The microstructure was characterized before and after refining. The effects of acid leaching, basicity, and slag/Si mass ratio on B removal were investigated. Experimental results showed that acid leaching had no effect on B removal from MG-Si but had a clear effect on the refined Si–Sn alloy after slag refining. The final B concentration was highly affected by the CaO/SiO2 mass ratio with minimum value, where the content of B was reduced from 18.36 ppmw to 5.5 ppmw at the CaO/SiO2 = 1.2 for MG-Si slag refining and from 18.36 ppmw to 3.7 ppmw at CaO/SiO2 = 1.5 for 75 wt% Si–Sn alloy. Increasing the slag mass ratio by 2:1 mass ratio also increased B removal efficiency by approximately 15–20% more than an increase by 1:1.

Computational studies of ice defects

2003 ◽  
Vol 81 (1-2) ◽  
pp. 325-332 ◽  
Author(s):  
P LM Plummer
Keyword(s):  
Defect Formation ◽  
Structural Evolution ◽  
Energy Difference ◽  
Electronic Energy ◽  
Energy Structure ◽  
Defect Site ◽  
And Migration ◽  
Dynamics Simulations ◽  
Small Clusters ◽  
Structure Calculations

Continuing our investigations of the energetics associated with defect formation and migration, both ab initio energy-structure calculations and molecular dynamics simulations are carried out on small clusters of water molecules containing one or more defects in hydrogen bonding. Previous studies in this series have identified structures containing defects that are stable at 0 K or that are transition states between such structures. However, results from this laboratory and elsewhere have shown that the energy required for the production or migration of a defect is more complex than merely the energy difference between the static structures. Cooperative motion of neighbors to the defect site can either increase or decrease the energy involved to produce or annihilate the defect. Thus, experimental measurements associated with the energy of defects in ice can differ substantially from those calculated using static models. By increasing the complexity of the model, the studies described in this report attempt to more realistically simulate a defect-containing ice system. The types of defects studied include ion and ion-pair defects. The initial structures are energetically stable — minima on the electronic energy surface — and contain one or more kinds of defects. Since the means and amount of energy injection can alter the migration path, the energy is introduced into the system in a variety of ways. The structural evolution of the ice system is then monitored as a function of time. PACS Nos.: 82.20Wt, 82.20Kh, 82.30Rs

New molecular insights into the stability of Ni–Pd hollow nanoparticles

2017 ◽  
Vol 4 (10) ◽  
pp. 1679-1690 ◽  
Author(s):  
Hamed Akbarzadeh ◽  
Esmat Mehrjouei ◽  
Amir Nasser Shamkhali ◽  
Mohsen Abbaspour ◽  
Sirous Salemi ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Thermal Behavior ◽  
Molecular Dynamics Simulations ◽  
Structural Evolution ◽  
Hollow Nanoparticles ◽  
The Stability ◽  
Dynamics Simulations

Molecular dynamics simulations were used to investigate the structural evolution and thermal behavior of Ni–Pd hollow nanoparticles.

scholarly journals Orientation Dependent Mechanical Responses and Plastic Deformation Mechanisms of ZnSe Nano Films under Nanoindentation

Nanomaterials ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 3014
Author(s):  
Chao Xu ◽  
Futi Liu ◽  
Chunmei Liu ◽  
Pei Wang ◽  
Huaping Liu
Keyword(s):  
Plastic Deformation ◽  
Elastic Recovery ◽  
Structural Evolution ◽  
Atomic Displacement ◽  
Deformation Mechanisms ◽  
Formation Mechanisms ◽  
Plastic Deformations ◽  
Mechanical Responses ◽  
Displacement Vectors ◽  
Dynamics Simulations

Although ZnSe has been widely studied due to its attractive electronic and optoelectronic properties, limited data on its plastic deformations are available. Through molecular dynamics simulations, we have investigated the indentations on the (001), (110), and (111) planes of ZnSe nano films. Our results indicate that the elastic modulus, incipient plasticity, elastic recovery ratio, and the structural evolutions during the indenting process of ZnSe nano films show obvious anisotropy. To analyze the correlation of structural evolution and mechanical responses, the atomic displacement vectors, atomic arrangements, and the dislocations of the indented samples are analyzed. Our simulations revealed that the plastic deformations of the indented ZnSe nano films are dominated by the nucleation and propagation of 1/2<110> type dislocations, and the symmetrically distributed prismatic loops emitted during the indenting process are closely related with the mechanical properties. By studying the evolutions of microstructures, the formation process of the dislocations, as well as the formation mechanisms of the emitted prismatic loops under the indented crystalline planes are discussed. The results presented in this work not only provide an answer for the questions about indentation responses of ZnSe nano films, but also offer insight into its plastic deformation mechanisms.

scholarly journals Slag Treatment Followed by Acid Leaching as a Route to Solar-Grade Silicon

JOM ◽  
2012 ◽  
Vol 64 (8) ◽  
pp. 957-967 ◽  
Author(s):  
Yulia V. Meteleva-Fischer ◽  
Yongxiang Yang ◽  
Rob Boom ◽  
Bert Kraaijveld ◽  
Henk Kuntzel
Keyword(s):  
Acid Leaching ◽  
Solar Grade Silicon ◽  
Slag Treatment ◽  
Grade Silicon

Reductive Removal of Phosphorus in Silicon Using CaO-CaF2 Slag

2013 ◽  
Vol 750 ◽  
pp. 284-287 ◽  
Author(s):  
Hiroaki Kawamura ◽  
Yutaka Yanaba ◽  
Takeshi Yoshikawa ◽  
Kazuki Morita
Keyword(s):  
Acid Leaching ◽  
Calcium Content ◽  
Molten Silicon ◽  
Metallurgical Grade Silicon ◽  
Slag Treatment ◽  
High Fraction ◽  
Wet Chemical ◽  
Grade Silicon ◽  
Removal Fraction ◽  
P Removal

In order to verify an alternative metallurgical process of phosphorus removal for solar grade silicon (SOG-Si), slag treatment of metallurgical grade silicon (MG-Si) was conducted followed by acid leaching in the present study. MG-Si containing certain amount of phosphorus and calcium was equilibrated at 1723 and 1773 K with several compositions of the CaO-CaF2 slags and phosphorus in molten silicon was confirmed to be removed into slag phase also by reducing reaction as a form of phosphide ion, P3-, in addition to the phosphate ion, PO43-. These contents were separately determined by a wet chemical analysis method developed by ourselves. Although the distribution ratio of phosphorus could not exceed the highest reported values of 3, subsequent leaching brought about considerably high fraction of P removal. The removal fraction of 95.6% was attained when 5 g of silicon was treated with 10 g of the slag at 1773 K followed by the acid leaching, which would be much higher than that expected by the ordinary oxidizing slag treatment. Although the possibility of reducing dephosphorization by slag treatment was clarified, more effective condition should be pursued by changing slag composition, calcium content of silicon, temperature, etc.

Structural evolution of TiAl during rapid solidification processing revealed by molecular dynamics simulations

RSC Advances ◽  
2016 ◽  
Vol 6 (60) ◽  
pp. 54763-54767 ◽  
Author(s):  
Peng-tao Li ◽  
Yan-Qing Yang ◽  
Wei Zhang ◽  
Xian Luo ◽  
Na Jin ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Rapid Solidification ◽  
Structural Evolution ◽  
Rapid Solidification Processing ◽  
Solidification Processing ◽  
Dynamics Simulations

In this paper, the processes of rapid solidification in TiAl was investigated by molecular dynamics simulations.

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