Effect of mixed rare earth oxides and CaCO3 modification on the microstructure of an in-situ Mg2Si/Al-Si composite

Rare Metals ◽  
2009 ◽  
Vol 28 (2) ◽  
pp. 169-174 ◽  
Author(s):  
Zheng Liu ◽  
Jixing Lin ◽  
Qingxiu Jing
Keyword(s):  
Rare Earth ◽  
Rare Earth Oxides

scholarly journals Effects of rare-earth oxides on the microstructure and properties of Fe-based friction materials synthesized by in situ carbothermic reaction from vanadium-bearing titanomagnetite concentrates

RSC Advances ◽  
2019 ◽  
Vol 9 (36) ◽  
pp. 20687-20697
Author(s):  
Dajun Zhai ◽  
Yue Shui ◽  
Keqin Feng ◽  
Yanyan Zhang
Keyword(s):  
Rare Earth ◽  
Tribological Properties ◽  
Rare Earth Oxides ◽  
Frictional Material ◽  
Friction Materials ◽  
Microstructure And Properties ◽  
Iron Based

In this work, we prepared an iron-based frictional material from vanadium-bearing titanomagnetite concentrates by in situ carbothermic reaction with improved tribological properties.

scholarly journals Catalytic Oxidation of HCHO over the Sodium-Treated Sepiolite-Supported Rare Earth (La, Eu, Dy, and Tm) Oxide Catalysts

Catalysts ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 328 ◽  
Author(s):  
Ning Dong ◽  
Qing Ye ◽  
Mengyue Chen ◽  
Shuiyuan Cheng ◽  
Tianfang Kang ◽  
...  
Keyword(s):  
Catalytic Activity ◽  
Rare Earth ◽  
Catalytic Oxidation ◽  
Rare Earth Oxide ◽  
Catalytic Performance ◽  
Rare Earth Oxides ◽  
Hydroxyl Groups ◽  
In Situ Drifts ◽  
The Rare Earth

The sodium-treated sepiolite (NaSep)-supported rare earth oxide (RE/NaSep; RE = La, Eu, Dy, and Tm) samples were prepared using the rotary evaporation method. Physicochemical properties of these materials were characterized by XRD, SEM, BET, FTIR, XPS, H2–TPR, NH3–TPD, and in situ DRIFTS, and their catalytic activities for formaldehyde (HCHO) (2000 ppm) oxidation were evaluated. The results show that loading of the rare earth oxide on NaSep improved its catalytic performance. Among all the samples, Eu/NaSep performed the best, and complete HCHO conversion was achieved at a temperature of 150 °C and a gas hourly space velocity of 240,000 mL/(g h); a good catalytic activity was still maintained after 45 h of stability test. The catalytic oxidation mechanism of HCHO was studied using the in situ DRIFTS technique. As a result, the effective and stable catalytic performance of the Eu/NaSep sample was mainly due to the presence of hydroxyl groups on the sepiolite surface and the doped rare earth oxides, which contributed to its high performance. HCHO oxidation underwent via the steps of HCHO + O2 → HCOO− + OH− → H2O + CO2. It is concluded that the optimal catalytic activity of Eu/NaSep was associated with the highest Oads/Olatt atomic ratio, the largest amount of hydroxyl groups, the highest acidity, and the best reducibility. The present work may provide new insights into the application in the removal of high-concentration HCHO over the rare earth oxides supported on natural low-cost clays.

Effect of Rare Earth Oxides on Electrical Properties of Spark Plasma Sintered AlN Ceramics

2015 ◽  
Vol 30 (3) ◽  
pp. 267
Author(s):  
HUANG Lin-Yun ◽  
LI Chen-Hui ◽  
KE Wen-Ming ◽  
SHI Yu-Sheng ◽  
HE Zhi-Yong ◽  
...  
Keyword(s):  
Rare Earth ◽  
Electrical Properties ◽  
Rare Earth Oxides ◽  
Spark Plasma

A glance on rare earth oxides: importance, reserves, demand, applications, critical uncertainties, global economy, and zeta potential characterization

2020 ◽  
Vol 05 ◽  
Author(s):  
Silas Santos ◽  
Orlando Rodrigues ◽  
Letícia Campos
Keyword(s):  
Rare Earth ◽  
Zeta Potential ◽  
Sample Preparation ◽  
Rare Earths ◽  
Smart Materials ◽  
Global Economy ◽  
Materials Science ◽  
Functional Materials ◽  
Rare Earth Oxides ◽  
Interparticle Forces

Background: Innovation mission in materials science requires new approaches to form functional materials, wherein the concept of its formation begins in nano/micro scale. Rare earth oxides with general form (RE2O3; RE from La to Lu, including Sc and Y) exhibit particular proprieties, being used in a vast field of applications with high technological content since agriculture to astronomy. Despite of their applicability, there is a lack of studies on surface chemistry of rare earth oxides. Zeta potential determination provides key parameters to form smart materials by controlling interparticle forces, as well as their evolution during processing. This paper reports a study on zeta potential with emphasis for rare earth oxide nanoparticles. A brief overview on rare earths, as well as zeta potential, including sample preparation, measurement parameters, and the most common mistakes during this evaluation are reported. Methods: A brief overview on rare earths, including zeta potential, and interparticle forces are presented. A practical study on zeta potential of rare earth oxides - RE2O3 (RE as Y, Dy, Tm, Eu, and Ce) in aqueous media is reported. Moreover, sample preparation, measurement parameters, and common mistakes during this evaluation are discussed. Results: Potential zeta values depend on particle characteristics such as size, shape, density, and surface area. Besides, preparation of samples which involves electrolyte concentration and time for homogenization of suspensions are extremely valuable to get suitable results. Conclusion: Zeta potential evaluation provides key parameters to produce smart materials seeing that interparticle forces can be controlled. Even though zeta potential characterization is mature, investigations on rare earth oxides are very scarce. Therefore, this innovative paper is a valuable contribution on this field.

Synthetic zircon doped with hafnium and rare earth elements: A reference material for in situ hafnium isotope analysis

2011 ◽  
Vol 286 (1-2) ◽  
pp. 32-47 ◽  
Author(s):  
Christopher M. Fisher ◽  
John M. Hanchar ◽  
Scott D. Samson ◽  
Bruno Dhuime ◽  
Janne Blichert-Toft ◽  
...  
Keyword(s):  
Rare Earth ◽  
Reference Material ◽  
Rare Earth Elements ◽  
Isotope Analysis

scholarly journals Start-up Strategies for Anaerobic Ammonia Oxidation (Anammox) in In-Situ Nitrogen Removal from Polluted Groundwater in Rare Earth Mining Areas

2021 ◽  
Vol 13 (8) ◽  
pp. 4591
Author(s):  
Shuanglei Huang ◽  
Daishe Wu
Keyword(s):  
Rare Earth ◽  
Low Temperature ◽  
Removal Efficiency ◽  
Nitrogen Removal ◽  
Ex Situ ◽  
High Concentration ◽  
Low Concentration ◽  
Start Up ◽  
Anammox Activity

The tremendous input of ammonium and rare earth element (REE) ions released by the enormous consumption of (NH4)2SO4 in in situ leaching for ion-adsorption RE mining caused serious ground and surface water contamination. Anaerobic ammonium oxidation (anammox) was a sustainable in situ technology that can reduce this nitrogen pollution. In this research, in situ, semi in situ, and ex situ method of inoculation that included low-concentration (0.02 mg·L−1) and high-concentration (0.10 mg·L−1) lanthanum (La)(III) were adopted to explore effective start-up strategies for starting up anammox reactors seeded with activated sludge and anammox sludge. The reactors were refrigerated for 30 days at 4 °C to investigate the effects of La(III) during a period of low-temperature. The results showed that the in situ and semi in situ enrichment strategies with the addition of La(III) at a low-concentration La(III) addition (0.02 mg·L−1) reduced the length of time required to reactivate the sludge until it reached a state of stable anammox activity and high nitrogen removal efficiency by 60–71 days. The addition of La(III) promoted the formation of sludge floc with a compact structure that enabled it to resist the adverse effects of low temperature and so to maintain a high abundance of AnAOB and microbacterial community diversity of sludge during refrigeration period. The addition of La(III) at a high concentration caused the cellular percentage of AnAOB to decrease from 54.60 ± 6.19% to 17.35 ± 6.69% during the enrichment and reduced nitrogen removal efficiency to an unrecoverable level to post-refrigeration.

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