CERAMICS INTERNATIONAL
·
2016
·
IF 2.758
Kangkang Yuan,Cong Feng,Xinzhu Gan,Zhichao Yu,Xinqiang Wang,Luyi Zhu,Guanghui Zhang,Dong Xu
Despite La 2 Zr 2 O 7 ceramic fiber has been fabricated by electrospinning method, the effects of thermal pyrolysis process on the microstructures and properties of the fibers have seldom been considered. Three La 2 O 3 precursors were used to prepare La 2 Zr 2 O 7 ceramic fibers. Phase transformation of La 2 Zr 2 O 7 ceramic fibers were characterized by XRD and Raman spectra. The influence of the decomposition process on the microstructure of the fibers was studied by TG/DSC, XPS and SEM. The results show that slow weight loss leads to smaller grain size which could obtain higher strength fibers while fast weight loss could develop pores which are benefit to the decrease of the thermal conductivity .
研究领域:
材料科学
·
陶瓷材料
✓ 已验证
产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2022
·
IF 7.392
Peng Miao,Weixing Chen,Weifeng Zhao,Jie Kong
Broadband microwave absorption materials have always been the goal of continuous pursuit. Hierarchical interfacial structure and impedance matching design are one of the effective strategies for enhancing broadband microwave absorption (MA) performance. However, the delicate hierarchical interfacial engineering design of magnetic-dielectric structures remains an ongoing challenge. In this work, the novel La(OH) 3 nanorods have been synthesized successfully, and the La(OH) 3 nanorods anchored on the surface of the metal–organic framework (ZIF-67) randomly to form a controllable impedance and hierarchical ZIF-67@La(OH) 3 precursor. After a harsh high-temperature pyrolysis procedure, the La 2 O 3 nanorods distribute on the surface of the Co/C polyhedral. The LaCoC-700 nanoparticles demonstrate superior MA performance because of the suitable impedance matching. The minimum reflection loss of the LaCoC-700 value reaches up to −63.0 dB at 3.94 mm, and the effective absorption bandwidth covers 8.56 GHz (9.44–18 GHz) at a thickness of 3.37 mm. Notably, introducing the La 2 O 3 nanorods can enhance the interface effect and impedance matching. With the synchronous loss process, the dielectric carbon and magnetic cobalt core can attenuate microwave effectively. This work provides a high and low dielectric loss combination strategy for designing broadband microwave absorbers.
研究领域:
材料科学
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电磁材料
·
纳米技术
✓ 已验证
产品关联
DOI
高影响因子
FUEL
·
2022
·
IF 8.035
Ji Zhao,Jing-Hui Lv,Xian-Yong Wei,Qian-Qian Kong,Jia-Hao Li,Yang-Yang Zhang,Zhuang Li,Li Li,Zi-Chun Fan,Zhi-Min Zong
Ni/CeO 2 -La 2 O 3 with strong acidity was prepared by in - situ carbon templating (ISCT) and subsequent reduction with H 2 . The phase composition, specific surface area, morphology, acidity, and elemental valence composition of the catalyst were characterized. The catalytic methylation (CM I ) of phenol over the catalyst in different ratios of methanol to n -hexane was investigated under N 2 atmosphere. Over the catalyst, phenol was completely converted into 2,6-xylenol at 260 °C for 3 h via the CM I of phenol to o -cresol and subsequent CM I of o -cresol.
研究领域:
催化化学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
International Journal of Applied Ceramic Technology
·
2023
·Vol. 21
·期 1
·51-61
·
IF 2.1
Xiong Gao,Deng Zhang,Xueru Feng,Jiamin Zhang,Yuqing Peng,Zhicheng Pan,Zongming Dai
The aim of this work is to prepare interlocking prismatic mullite from low-cost associated rare-earth kaolin. High-performance mullite was synthesized by reaction sintering using calcined associated rare-earth kaolin and α-Al 2 O 3 as raw materials and micro- and nano-La 2 O 3 as additives. The mineralogical, morphological, and chemical characteristics of calcined associated rare earth kaolin were analyzed, and the effects of the addition of micro- and nano-La 2 O 3 and sintering temperature on the phase transformation, sintering process, microstructure, and mechanical properties of mullite were studied. The results show that the associated rare earth elements Ce, Th, and Y in calcined kaolin are mainly light rare earth elements, which are mainly endowed in the interlayer structure of K-bearing clay minerals. The addition of La 2 O 3 can promote the growth of secondary mullite grains and accelerate the secondary mullitization process. The relative densities of mullite samples adding 4 wt.% micro/nano La 2 O 3 and sintered at 1500°C for 4 h were 92.72% and 93.4%, and the micro Vickers hardnesses were 11.32 and 12.35 GPa, respectively. The mullite sample with 2 wt.% nano-La 2 O 3 had the most interlaced prismatic grains, resulting in the highest flexural strength of 157.8 MPa.
研究领域:
材料科学
·
陶瓷学
✓ 已验证
产品关联
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2025
·
IF 5.6
Zhuoqing An,Yuan Gao,Jiajing Chen
The CaO-MgO-Al 2 O 3 -SiO 2 (CMAS) glass-ceramics containing complex nucleation agents including La 2 O 3 and Fe 2 O 3 were prepared by melt process. The effects of these complex nucleation agents on the crystallization and microstructure of CMAS glass-ceramics were investigated through the thermal analysis (DSC), X-ray diffraction (XRD), optical microscopy, scanning electron microscopy (SEM) and Raman spectroscopy. The results indicated that the addition of La 2 O 3 and Fe 2 O 3 decreases viscosity and ion movement resistance. Furthermore, the La 2 O 3 can increase the crystallization peak temperature, while the Fe 2 O 3 has an inverse effect. The crystallization activation energy decreased from 298.87 to 264.26 kJ/mol as the mole ratio of La 2 O 3 increased to 2%. Conversely, when the mole ratio of Fe 2 O 3 increased to 2%, the crystallization activation energy increased from 298.87 to 347.21 kJ/mol. However, the addition of La 2 O 3 and Fe 2 O 3 decreased the Avrami parameter and promoted the surface crystallization within the CMAS glass system, as confirmed by the microstructure analysis. The crystal show branch-like crystal morphology when La 2 O 3 adding, whereas Fe 2 O 3 addition led to a compact, seaweed-like morphology with a fractal structure. With decreasing La 2 O 3 and increasing Fe 2 O 3 , the width of the dendritic branches increased. The major crystal phases detected on the surface were augite and diopside phase. Fe is predominantly present in the augite phase and La is primarily incorporated as a solid solution within the crystal phase.
研究领域:
材料科学
·
化学
✓ 已验证
产品关联
DOI
高影响因子
RSC Advances
·
2016
·Vol. 6
·期 101
·99353-99360
·
IF 3.289
Jiaojie He,Wei Wang,Wenxin Shi,Fuyi Cui
La2O3 nanoparticle-doped PAN nanofiber mats were prepared by an electrospinning process. During the formation process, PAN nanofibers served as the matrix for immobilizing the La2O3 nanoparticles. Due to the great hydrophilicity of PAN nanofibers and the strong chemical affinity of phosphate/lanthanum bonds, the functional composite nanofiber mats exhibited high removal capacity for phosphate with a maximum adsorption capacity of 77.76 mg P per g (La), which guaranteed severe phosphate-deficient conditions. The effects of both the effective nutrient (phosphate) starvation and the close contact of E. coli with composites led to great antibacterial activity. The nutrient starvation (indirect antibacteria) was proved to be the primary mechanism. The intimate contact (direct antibacteria) was revealed as a supplementary role that only induced cell death without the existence of phosphate. The results demonstrated the feasibility of this antibacterial strategy through phosphate-starvation. In addition, the composite nanofiber mats implied a practical application by virtue of a simple fabrication and easy separation from the heterogeneous systems after using.
研究领域:
材料科学
·
生物医学工程
·
环境科学
✓ 已验证
产品关联
DOI
高影响因子
APPLIED CATALYSIS B-ENVIRONMENTAL
·
2016
·
IF 8.328
Xinyu Li,Di Li,Hao Tian,Liang Zeng,Zhi-Jian Zhao,Jinlong Gong
This paper describes the design of a Ni/La 2 O 3 catalyst using La 2 O 2 CO 3 nanorod as a support precursor (denoted as Ni/La 2 O 3 -LOC) via a wet impregnation method for dry reforming of methane (DRM). The results showed that La 2 O 3 derived from the La 2 O 2 CO 3 precursor maintained its initial morphology upon thermal treatment and could highly disperse Ni particles on it. Additionally, the nanorod-shaped support could provide more medium-strength basic sites to facilitate CO 2 adsorption and activation on its surface. Consequently, the Ni/La 2 O 3 -LOC catalyst reached 70% of CH 4 conversion and 75% of CO 2 conversion at 700 °C after 50 h DRM reaction with a H 2 /CO ratio of 0.87. The enhanced metal-support interaction restricted the sintering of nickel particles under harsh reaction conditions. Coke evolution on the catalysts was also investigated to understand coke formation mechanism and the role of La 2 O 2 CO 3 in coke elimination. It has been found that nickel dispersion can affect distribution of coke and La 2 O 2 CO 3 on the surface of catalyst, both of which have a close relation with catalytic performance.
研究领域:
化学工程
·
催化材料科学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2016
·
IF 3.205
Yu-Jie Zhong,Hong-Bin Dai,Min Zhu,Ping Wang
Hydrous hydrazine (N 2 H 4 ⋅H 2 O) has attracted considerable interest as a potential hydrogen carrier for vehicular or portable applications. But currently, most of published experimental works focus on dilute N 2 H 4 ⋅H 2 O solution with a limited hydrogen capacity to 2 wt%, which is well below the practical requirements. Herein, we report the catalytic decomposition of concentrated N 2 H 4 ⋅H 2 O solution over a La 2 O 3 -supported Ni Pt alloy catalyst . The Ni Pt/La 2 O 3 catalyst prepared by a one-pot co-precipitation method shows exceptionally high catalytic activity and 100% selectivity towards hydrogen generation from N 2 H 4 ⋅H 2 O at ambient temperatures. In particular, our study has demonstrated, for the first time, that the system composed of concentrated N 2 H 4 ⋅H 2 O solution, high-performance Ni Pt/La 2 O 3 catalyst and appropriate amount of alkali promoter can yield a material-based hydrogen capacity of 6 wt%. This finding is of clear significance for promoting the practical application of N 2 H 4 ⋅H 2 O as a viable hydrogen carrier.
研究领域:
化学工程
·
材料科学
·
能源技术
✓ 已验证
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
·
2023
·
IF 9.9
Shuai Dai,Chang Sun,Yuhe Zhang,Lingzhi Zeng,Yiqiong Peng,Liyuan Zhou,Yanlong Wang,Jian Jiang,Chang Ming Li
Practical utilization of Li-sulfur batteries (LSBs) is still hindered by the sulfur cathode side due to its inferior electrical conductivity , huge volume expansion and adverse polysulfide shuttling effects. Though using polar catalysts coupled with mesoporous carbons may well surmount these barriers, such unsheltered catalysts rarely survive due to oversaturated polysulfide adsorption and extra sulfuration side reactions. To overcome above constrains, we herein propose to implant highly reactive nanocatalysts into carbon matrix with few nanometers insertion depth for mechanical protection. As a paradigm study, we have embedded La 2 O 3 -quantum dots (QDs) into carbon nanorods , which are then assembled into carbon microspheres (CMs). As evaluated, La 2 O 3 QDs-CMs can help elevate the cathode redox reaction kinetics and sulfur utilization ratios, delivering a large capacity of 1392 mAh g −1 at 0.25C and high-capacity retention of 76% after total cycling. The thin carbon layers on La 2 O 3 QDs exert a key role in impeding excess polysulfide accumulation on catalysts and thus prevent their deactivation/failure. Our strategy may guide a smart way to make catalysts-involved sulfur cathode systems with ultra-long working durability for LSBs applications.
研究领域:
材料科学
·
电化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2024
·
IF 5.1
Qingxuan Zhou,Yang Wang,Zhuoqun Han,Jia Liu,Jie Zhao,Wei Chu,Zhicheng Zhao,Jian Li,Zhiqiang Cheng,Ling Li,Futian Liu
Due to the low powder content characteristic of digital light processing in the preparation of ceramic green bodies, significant challenges arise in obtaining high-density, high-performance Si 3 N 4 ceramic. Sintering aids exert a critical influence on the densification and properties of Si 3 N 4 ceramics. To further improve the performance of 3D-printed Si 3 N 4 ceramics, Si 3 N 4 ceramics were fabricated using DLP technology combined with gas pressure sintering employing different ratios of La 2 O 3 -MgO as sintering aids. The ceramic slurries, microstructures, and ceramic performance were studied systematically. The results showed that increasing the proportion of· La 2 O 3 powder enhanced the rheological and curing properties of Si 3 N 4 ceramic slurries. Varying the La 2 O 3 -MgO ratio affected the composition of the liquid phase, leading to differences in the densification and grain growth of Si 3 N 4 ceramics. The average grain size increased with higher ratios of La 2 O 3 -MgO, and reached a maximum value of 0.91 μm with a ratio of 9:1. With the increase of the La 2 O 3 -MgO ratio, the bulk density and shrinkage rate of the ceramics initially increased and then declined. In addition, the flexural strength and fracture toughness of the ceramics peaked at a ratio of 3:7 for La 2 O 3 -MgO, measuring 577 ± 16.28 MPa and 5.84 ± 0.17 MPa m 1/2 , respectively. These results demonstrate that high-performance Si 3 N 4 ceramics can be effectively prepared using DLP technology by adapting the ratio of sintering additives.
研究领域:
材料科学
·
陶瓷工程
✓ 已验证
产品关联
DOI
高影响因子
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
·
2023
·Vol. 25
·期 22
·15547-15554
·
IF 3.3
Changyin Zhong,Yifei Yang,Yun Fang,Jun Chen,Bomin Feng,Hongbing Wang,Wenhua Luo,Yunxi Yao
Lanthanum oxide (La2O3) possesses superior reactivity during catalytic hydrogenation, but the intrinsic activity of La2O3 toward H2 adsorption and activation remains unclear. In the present work, we fundamentally investigated hydrogen interaction with Ni-modified La2O3. Hydrogen temperature programmed desorption (H2-TPD) on Ni/La2O3 shows enhanced hydrogen adsorption with a new hydrogen desorption peak at a higher temperature position compared to that on the metallic Ni surfaces. By systematically exploring the desorption experiments, the enhanced H2 adsorption on Ni/La2O3 is due to the oxygen vacancies formed at the metal–oxide interfaces. Hydrogen atoms transfer from Ni surfaces to the oxygen vacancies to form lanthanum oxyhydride species (H–La–O) at the metal–oxide interfaces. The adsorbed hydrogen at the metal–oxide interfaces of Ni/La2O3 results in improved catalytic reactivity in CO2 methanation. Furthermore, the enhanced hydrogen adsorption on the interfacial oxygen vacancies is ubiquitous for La2O3-supported Fe, Co, and Ni nanoparticles. Benefiting from the modification effect of the supported transition metal nanoparticles, the surface oxyhydride species can be formed on La2O3 surfaces, which resembles the recently reported oxyhydride observed on the reducible CeO2 surfaces with abundant surface oxygen vacancies. These findings strengthen our understanding of the surface chemistry of La2O3 and shed new light on the design of highly efficient La2O3-based catalysts with metal–oxide interfaces.
研究领域:
催化
·
表面化学
·
材料科学
✓ 已验证
DOI
高影响因子
Coatings
·
2023
·Vol. 13
·期 6
·1085
·
IF 3.4
Zhenchuan Lu,Kamale Tuokedaerhan,Haotian Cai,Hongguo Du,Renjia Zhang
This article presents the sol-gel method for depositing La2O3thin films on n-type Si substrates and quartz substrates, and investigates the impact of annealing temperature on the microcomposition, surface morphology, optical properties, and band characteristics of the films. X-ray diffraction (XRD) analysis indicates that the films are amorphous below 500 °C, with annealing resulting in a hexagonal-phase La2O3(h-a2O3) and new non-hydrated impurities. Fourier-transform infrared (FTIR) analysis reveals that the prepared La2O3film is unaffected by moisture. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) provide evidence that the La2O3film has a smooth, uniform surface without cracks. The roughness increases from 0.426 nm to 1.200 nm, and the film thins from 54.85 nm to 49.80 nm as the annealing temperature rises. The film’s transmittance is above 75%, as measured by UV-Vis, and the calculated optical bandgap increases from 5.11 eV to 5.75 eV. The calculated band offset of the La2O3film is greater than 1 eV, which meets the minimum requirements for MOS devices, thus providing promising prospects for La2O3films in MOS applications.Keywords:high k gate dielectric;sol-gel;La2O3;thin film
研究领域:
材料科学
·
半导体物理
✓ 已验证
产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）