rare earth oxide
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Author(s):  
SAGARIKA KHOUND ◽  
Jayanta Kumar Sarmah ◽  
RANJIT SARMA

Abstract In this work, we have studied the electrical performance of cross-linked polyvinyl phenol (cPVP) modified lanthanum oxide (La2O3) bilayer dielectric film in pentacene thin film transistors (TFT). A simple spin-coating and room temperature operated cross-linking reaction of the hydroxyl moieties of PVP and the nitrogen groups of PMF were carried out to form the cross-linked PVP. The deposition of a thin 30 nm cPVP layer over the La2O3 layer provided a low leakage current (<10−7A/cm2), causing a reduction in the interface trap density. Besides, the modified surface properties of the La2O3 layer were favorable for the growth of pentacene organic semiconductors. As a result, the current on-off ratio and the sub-threshold slope was improved from 104 and 1.0 V/decade to 105 and 0.67 V/decade. The La2O3∕cPVP pentacene TFT operated at −10 V also exhibited improvement in the field-effect mobility to 0.71 cm2/Vs from 0.48 cm2/Vs for the single-layer La2O3 (130 nm) device. Thus, our work demonstrates that the rare earth oxide La2O3 with cPVP is an excellent dielectric system in the context of emerging transistors with hybrid polymer gate dielectrics.


2022 ◽  
Author(s):  
Samane Maroufi ◽  
Sajjad S. Mofarah ◽  
Rasoul Khayyam Nekouei ◽  
Veena Sahajwalla

Growing utilisation of rare earth elements (REEs) has caused serious shortages in REEs’ supply and shifting state-of-the-art approaches toward sustainable recycling of existing REEs. The present work details a three-stage...


Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7432
Author(s):  
Radu-Robert Piticescu ◽  
Anca Elena Slobozeanu ◽  
Sorina Nicoleta Valsan ◽  
Cristina Florentina Ciobota ◽  
Andreea-Nicoleta Ghita ◽  
...  

Zirconium dioxide (ZrO2) is one of the ceramic materials with high potential in many areas of modern technologies. ZrO2 doped with 8 wt.% (~4.5 mol%) Y2O3 is a commercial powder used for obtaining stabilized zirconia materials (8 wt.% YSZ) with high temperature resistance and good ionic conductivity. During recent years it was reported the co-doping with multiple rare earth elements has a significant influence on the thermal, mechanical and ionic conductivity of zirconia, due complex grain size segregation and enhanced oxygen vacancies mobility. Different methods have been proposed to synthesize these materials. Here, we present the hydrothermal synthesis of 8 wt.% (~4.5 mol%) YSZ co-doped with 4, 6 and 8 wt.% La2O3, Nd2O3, Sm2O3 and Gd2O3 respectively. The crystalline phases formed during their thermal treatment in a large temperature range were analyzed by X-ray diffraction. The evolution of phase composition vs. thermal treatment temperatures shows as a major trend the formation at temperatures >1000 °C of a cubic solid solutions enriched in the rare earth oxide used for co-doping as major phase. The first results on the thermal conductivities and impedance measurements on sintered pellets obtained from powders co-doped with 8 wt.% Y and 6% Ln (Ln = La, Nd, Sm and Gd) and the corresponding activation energies are presented and discussed. The lowest thermal conductivity was obtained for La co-doped 8 wt.% YSZ while the lowest activation energy for ionic conduction for Gd co-doped 8 wt.% YSZ materials.


2021 ◽  
Vol 12 ◽  
Author(s):  
Yong-Jun Liu ◽  
Zhongwang Jing ◽  
Xue-Ting Bai ◽  
Qing-Yun Diao ◽  
Jichen Wang ◽  
...  

Honeybees (Apis mellifera) can be exposed via numerous potential pathways to ambient nanoparticles (NPs), including rare earth oxide (REO) NPs that are increasingly used and released into the environment. Gut microorganisms are pivotal in mediating honeybee health, but how REO NPs may affect honeybee health and gut microbiota remains poorly understood. To address this knowledge gap, honeybees were fed pollen and sucrose syrup containing 0, 1, 10, 100, and 1000mgkg−1 of nano-La2O3 for 12days. Nano-La2O3 exerted detrimental effects on honeybee physiology, as reflected by dose-dependent adverse effects of nano-La2O3 on survival, pollen consumption, and body weight (p&lt;0.05). Nano-La2O3 caused the dysbiosis of honeybee gut bacterial communities, as evidenced by the change of gut bacterial community composition, the enrichment of pathogenic Serratia and Frischella, and the alteration of digestion-related taxa Bombella (p&lt;0.05). There were significant correlations between honeybee physiological parameters and the relative abundances of pathogenic Serratia and Frischella (p&lt;0.05), underscoring linkages between honeybee health and gut bacterial communities. Taken together, this study demonstrates that nano-La2O3 can cause detrimental effects on honeybee health, potentially by disordering gut bacterial communities. This study thus reveals a previously overlooked effect of nano-La2O3 on the ecologically and economically important honeybee species Apis mellifera.


Author(s):  
Eduardo de Sousa Lima ◽  
Camila Catalano Gall ◽  
Manuel Fellipe R.P. Alves ◽  
José Brant de Campos ◽  
Tiago Moreira Bastos Campos ◽  
...  

2021 ◽  
Vol 13 (23) ◽  
pp. 13205
Author(s):  
Jing An ◽  
Aitian Tao ◽  
He Yang ◽  
Ang Tian

In recent years, the rapid development of the rare earth industry has had a serious impact on the environment. Some enterprises have taken measures to improve the production process. In order to explore the sustainability of this industry and these improvements’ environmental benefits, this paper combines emergy analysis and lifecycle assessment to evaluate and compare the production process of rare-earth oxides considering the three aspects of emergy flow, pollutant emissions, and emergy-based indicators. Changes in the emergy of pollutant emissions before and after improvement of the production process are discussed. The results show that the greatest inputs in the mining and beneficiation stage and smelting separation stage are labor force and service and non-renewable resources, respectively. These two production stages are highly dependent on external input and have weak competitiveness. Both stages place great pressure on the environment, so the bastnasite production process would be unsustainable in the long term. After the improvement, the environmental impact of the production process for bastnaesite changed significantly, indicating that the improvement effect of the wastewater treatment facilities and the change of fuel from coal to natural gas is remarkable.


2021 ◽  
Vol 11 (23) ◽  
pp. 11177
Author(s):  
Zhenghua Guo ◽  
Surui Li ◽  
Qingjie Wu ◽  
Ning Li

In this study, graphene nanoplatelets (GNPs) decorated rare earth oxide CeO2 (CeO2@GNPs) were synthesized by alcohol thermal reaction method and used to reinforce GNPs/2024Al composites fabricated by a pressure sintering process. The results indicated that the decorating CeO2 particles could further promote the dispersion of the GNPs as well the binding of GNPs to the matrix. As a result, the as-prepared 0.5 wt.% CeO2@GNPs/2024Al composites exhibited yield strength and tensile strength increased by 21.1% and 24.7% compared to these of the matrix, respectively. It is better than the mechanical strength values of the composite enforced with the raw GNPs of the same quality. The optimization of GNPs dispersibility and interfacial bonding with Al matrix promotes its effective role in load-bearing strengthening.


2021 ◽  
Author(s):  
Xuejun Xu ◽  
Tomohiro Inaba ◽  
Tai Tsuchizawa ◽  
Atsushi Ishizawa ◽  
Haruki Sanada ◽  
...  

Author(s):  
Roy López-Sesenes ◽  
Jose Gonzalo González-Rodríguez ◽  
José Gerardo Vera-Dimas ◽  
Rene Guardian-Tapia ◽  
Luis Cisneros-Villalobos

The effect of the galvanic corrosion process taking place between aluminium alloy (AA2024-T3) and carbon fiber reinforced plastic (CFRP) immersed in 0.05 M NaCl was studied using organic and inorganic compounds as corrosion inhibitors. Electrochemical approaches such as electrochemical noise analysis (ENA) and electrochemical impedance spectroscopy (EIS) were carried out to evaluate efficiencies of 1,2,4-triazole (C2H3N3) and cerium nitrate hexahydrate (Ce(NO3)3·6H2O) as corrosion inhibitors. The highest efficiency was reached for Ce(NO3)3.6H2O, with some improvement observed by adding C2H3N3 in a mixed inhibitor solution. The noise resistance (Rn) and polarization resistance (Rp) values calculated from ENA and EIS data showed almost identical behavior with different magni­tudes but similar trends. Adsorption isotherm models estimated with fractional surface coverage (q) parameter were fitted better to Langmuir model for C2H3N3 and Temkin model for Ce(NO3)3·6H2O. The calculated values of Gibbs free energy suggested physi­sorption and chemisorption as spontaneous interactions between a metal surface and both inhibitors. Energy-dispersive X-ray spectroscopy (EDS) was carried out before and after immersing AA2024-T3 in the electrolyte, identifying rich zones in copper with cerium deposited over it and confirming the presence of rare-earth oxide deposition and oxide film products. The EDS analysis for CFRP revealed the deposition of Ce and Al particles over its surface after immersion in the electrolyte, especially in the areas rich in carbon.


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