Influence of thermal process on particle size distribution of ultrafine magnesium powder prepared by inert gas condensation method

Wen, Ya

doi:10.1016/j.powtec.2015.08.001

Cited by 7 publications

(2 citation statements)

References 23 publications

(26 reference statements)

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“…A supersaturated mixture is formed; meanwhile, homogeneous nucleation of Ge vapor could occur. Once nucleate particles are formed in the gas phase, they would coagulate at a rate that is proportional to the square of their concentration. , Aggregated small particles of Ge form larger particles with a hexagonal crystal structure. The morphology of the metal Ge is shown by SEM in Figure c.…”

Section: Resultsmentioning

confidence: 99%

Thermodynamics, Kinetics Model, and Reaction Mechanism of Low-Vacuum Phosphate Reduction Process for Germanium Recovery from Optical Fiber Scraps

Zhang

Song

2018

ACS Sustainable Chem. Eng.

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Germanium, because of its unique performance, has been widely used in the manufacture of optical fiber. Recycling germanium is significant because of geographical scarcity and technical barriers. In this study, a novel low-vacuum phosphate reduction process of GeO2 was proposed to recover germanium from optical fiber scraps. The thermodynamics, kinetics model, product analysis, and reaction mechanism were studied. Thermodynamic results indicated that the decomposition products were mainly the P(V) compounds Na4P2O7 and Na5P3O10, PH3, O2, and H2. The reaction order models of dα/dt = 1.44 × 108 exp(−212000/8.314T)(1 – α)3.63 min–1 can describe the kinetic results of the phosphate reduction process well. The average activation energy E̅ α located around 212 kJ mol–1. The chemical species of Ge in the condensed products were metal Ge, Ge(II), and a small amount of Ge(IV) by XPS analysis. A hydrolysis reaction followed by a nucleophilic addition–elimination mechanism can explain the decomposition of NaH2PO2. Then, a mechanism of collapse of the GeO2 octahedron by the action of PH3(g) and H2 was presented to clarify the formation of Ge and its oxides. Finally, a nucleation mechanism under low-vacuum conditions explained the distribution of condensed products. We quantitatively investigated the vacuum phosphate reduction process and can successfully guide germanium recovery from optical fiber scraps.

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Section: Resultsmentioning

confidence: 99%

Thermodynamics, Kinetics Model, and Reaction Mechanism of Low-Vacuum Phosphate Reduction Process for Germanium Recovery from Optical Fiber Scraps

Zhang

Song

2018

ACS Sustainable Chem. Eng.

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“…In our previous study of metallic NPs, we made the assumption that the morphology of NPs was spherical [39,43]. In this paper, we want to determine under which conditions this hypothesis will be appropriate.…”

Section: Resultsmentioning

confidence: 99%

A thermodynamics model for morphology prediction of aluminum nano crystals fabricated by the inert gas condensation method

Wen

2018

Nanotechnology

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The purpose of this study is to provide scientific guidance for the morphological control of nanoparticle synthesis using the gas phase method. A universal thermodynamics model is developed to predict the morphology of nanoparticles fabricated using the inert gas condensation method. By using this model, the morphologies of aluminum nanocrystals are predicted under various preparation conditions. There are two types of energy that jointly determine the formation of nanoparticle morphology-Gibbs free energy for nanoparticles and energy variation during the process. The results show that energy variation dominates morphology formation when the cooling rate is less than 2 × 10 K s in the aluminum nanocrystal production process. At the beginning of the nanoparticle growth, the most stable morphology is predicted to be spherical, but the energetically preferred morphology becomes cubic as the particle grows. The turning point in the particle size at which spherical morphology is no longer the most stable morphology is exhibited as a function of pressure in a condensation chamber for different cooling rates. In this paper, we focus on the need for morphology prediction based on preparation conditions. It is concluded that nanoparticles with various morphologies could be obtained by adjusting the cooling rate and pressure in the condensation chamber.

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Growth, characterization and thermo-mechanical analysis of Al/Al2O3 core/shell nanoparticles obtained under H2 atmosphere

Díaz-Droguett

Ramos-Moore

Roble

et al. 2020

Ceramics International

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Influence of thermal process on particle size distribution of ultrafine magnesium powder prepared by inert gas condensation method

Cited by 7 publications

References 23 publications

Thermodynamics, Kinetics Model, and Reaction Mechanism of Low-Vacuum Phosphate Reduction Process for Germanium Recovery from Optical Fiber Scraps

Thermodynamics, Kinetics Model, and Reaction Mechanism of Low-Vacuum Phosphate Reduction Process for Germanium Recovery from Optical Fiber Scraps

A thermodynamics model for morphology prediction of aluminum nano crystals fabricated by the inert gas condensation method

Growth, characterization and thermo-mechanical analysis of Al/Al2O3 core/shell nanoparticles obtained under H2 atmosphere

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