JOURNAL OF NUCLEAR MATERIALS
·
2014
·
IF 2.016
Xin Wang,Kuo Jiang,Liang Zhou
Powders of (Nd 1− x Ce x ) 2 Zr 2 O 7+ y ( x = 0–1) with pyrochlore structure were prepared by sol-spray pyrolysis and subsequent graphite reduction at 1200 °C. The effects of cerium content on crystal structure, phase stability and microstructure of the (Nd 1− x Ce x ) 2 Zr 2 O 7+ y ( x = 0–1) inert matrix materials were studied. XRD and Raman results presented that all samples were in a single pyrochlore phase. XPS results indicated the cerium was in a single oxidation state of +4. After sintering at 1500 °C for 24 h in air, the sample of x = 1 underwent a phase segregation to Zr 1− x Ce x O 2 solid solutions of tetragonal, metastable tetragonal and cubic phases, the sample of x = 0.9 contained a few tetragonal phase in addition to fluorite phase, the samples of x = 0.5–0.8 had a single phase fluorite structure, the samples of x = 0–0.4 maintained the pyrochlore structure.
研究领域:
材料科学
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THERMAL ANALYSIS AND CALORIMETRY
·
2021
·Vol. 147
·期 3
·2239-2251
·
IF 4.626
Zhao Qian,Wang Bowen,Qin Chenyuan,Li Qiuxuan,Liu Chuntai,Shen Changyu,Wang Yaming
In this work, biodegradable poly(lactic acid) (PLA)/Ti 3 C 2 T x MXene nanocomposites were prepared through melt compounding. The roles of MXene in nonisothermal melt and cold crystallization of PLA were explored. The morphology, structure and crystallization behavior were studied using polarized optical microscopy, wide-angle X-ray diffraction and differential scanning calorimetry. For nonisothermal melt crystallization, the presence of MXene increases the crystallinity and shortens the half-crystallization time but does not change the crystallization peak temperature of PLA. For nonisothermal crystallization from the glassy state, the incorporation of MXene decreases the cold crystallization peak temperature and reduces the crystallinity marginally but does not affect the half-crystallization time of PLA. The crystallization kinetics analysis based on the Avrami equation shows that, for both the melt and cold crystallization, the crystallization mechanism is unchanged irrespective of the addition of MXene. The investigation would be useful for understanding the correlation between processing and properties of PLA/MXene nanocomposites.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
MACROMOLECULES
·
2017
·
IF 5.835
Dongdong Zhou,Shaoyong Huang,Jingru Sun,Xinchao Bian,Gao Li,Xuesi Chen
The crystallization behaviors and microstructures of poly(l-2-hydroxyl-3-methylbutanoic acid)/poly(l-lactide) blends [P(L-2H3MB)/PLLA] were investigated by OM, DSC, SAXS, in situ temperature-dependent WAXD, and in situ synchrotron WAXS. The blends exhibited a homogeneous state at 250 °C. In the cooling process, P(L-2H3MB), with higher melting temperature, crystallized first at 166.7 °C and drove the formation of the phase separation and microstructure. And the amorphous P(L-2H3MB) and PLLA were excluded into the interlamellar and interfibrillar regions of the former P(L-2H3MB) crystallites. For P(L-2H3MB)/PLLA (5/5), the amorphous P(L-2H3MB) in the interfibrillar regions continued to form crystallites sequentially at 134.6 °C, which clearly confirmed the fractional crystallization of P(L-2H3MB). In our knowledge, this unique fractional crystallization has not been reported yet, of the component in miscible blend, which crystallized first under little confinement. This work provided a new viewpoint and understanding of the relationship between fractional crystallization and microstructures in crystalline/crystalline blends.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF ELECTRONIC MATERIALS
·
2020
·Vol. 49
·期 4
·2608-2616
·
IF 1.774
Chen Gang,Ji Cong,Fan Tao,Li Jiahua,Fu Chunlin,Cai Wei,Gao Rongli,Wang Zhenhua,Deng Xiaoling,Fan Peigeng
The (1 − x ) Bi (Fe 0.9 Al 0.05 Yb 0.05 ) O 3 – x BaTiO 3 (BFAYO- x BTO) ceramics were synthesized by microwave sintering (MWS) and conventional sintering (CS) methods. The crystal structure, surface morphology, dielectric and ferroelectric properties were investigated. XRD patterns show that BTO tetragonal and BFO rhombohedral phases coexist in both MWS and CS samples, and that the diffraction peaks of MWS samples shift to lower angles due to the larger ionic radius of Ba 2+ compared with Bi 3+ . The lattice constant of BFAYO- x BTO ceramics increases with the increase of BTO content. It was found that the average grain size of the MWS ceramic is much smaller than that of the CS ceramic. Dielectric measurements reveal that the dielectric loss and dielectric constant increase with BTO content increasing. The introduction of BTO into BFAYO-based ceramic contribute to the enhancement of the dielectric relaxation behavior. The P – E hysteresis loops demonstrate that the remnant polarization ( P r ) and the coercive field ( E C ) of the MWS samples are smaller than those of the CS samples. P r and E C first increase, then decrease and then increase again with the increase of BTO content. The maximum and minimum values of the remnant polarization were obtained at x = 0.25 and 0.3, respectively.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
JOURNAL OF ALLOYS AND COMPOUNDS
·
2024
·
IF 5.8
Chengjian Ma,Longhua He,Haiyun Ruan,Hong Gao,Jianxiang Ding
In this study, Co 0.98 Cu 0.4 Mn 1.62 O 4 ceramics with dual phases and twin defects were successfully prepared by the thermal decomposition of oxalate precursors. The effects of sintering temperature on the phase composition, microstructure, and electrical properties of Co 0.98 Cu 0.4 Mn 1.62 O 4 ceramics were investigated. X-ray diffraction results show that the ceramics are composed of cubic and tetragonal spinel phases and the content of the cubic spinel phase increases with increasing sintering temperature. Scanning electron microscopy images revealed that the grain size increases with increasing sintering temperature and the bulk density first increases and then decreases. Transmission electron microscopy results revealed a change in the twin configuration from needle-shaped twins to lamella without internal twins and finally to lamella with internal twins with increasing sintering temperature. X-ray photoelectron spectroscopy results showed that an increase in the sintering temperature causes the oxidation of Cu + to Cu 2+ , and the average valence state of Mn ions to first increase and then decrease. However, during the aging process, Cu + did not oxidize to Cu 2+ and the Cu + content increased. Co 0.98 Cu 0.4 Mn 1.62 O 4 ceramics sintered in the temperature range of 1000°C–1200°C exhibited excellent electrical properties. The resistivity ( ρ 25 ), material constant ( B 25/85 ), and aging values were 17.6–106.66 Ω·cm, 2836–3338 K, and 1.63%–3.41%, respectively. Herein, the relationships among the microstructures, valence states, and electrical properties are also discussed in detail.
研究领域:
材料科学
·
无机化学
✓ 已验证
产品关联
DOI
高影响因子
COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS
·
2022
·
IF 5.518
Yiming Jian,Hongtao Gao,Yuying Yan
Superhydrophobic surfaces with micron-nanosized two-tiered structures have huge potential in practical applications. However, the complex preparation process and low-stability of the versatile superhydrophobic surfaces restricted their wide application. Herein, a facile chemical etching process was applied to create a micron-sized rough structure on the 1060 aluminum alloy substrate, and the micron-sized rough structure surface (M-surface) was hydrophobic with a water contact angle of 113.50° ± 2.7°. Then, the M-surface was modified by hydrophobic SiO 2 nanoparticles , and a superhydrophobic micron-nanosized two-tiered structure surface (MNSS-TMES/H-SiO 2 coating) with a water contact angle of 161.20° ± 2.3° was constructed. The as-prepared MNSS-TMES/H-SiO 2 coating can maintain superhydrophobicity after self-cleaning, sand impact, and anti-frosting tests. More importantly, the MNSS-TMES/H-SiO 2 coating exhibited superior anti-icing performance and higher defrosting efficiency. The freezing delay time of a water droplet on the MNSS-TMES/H-SiO 2 coating was prolonged to 4973.87 s at − 15 °C, and the frost layer on the resultant coating was melting speedily and turned into several isolated spherical water droplets in approximately 20 s. Therefore, the prepared durable fluorine-free superhydrophobic MNSS-TMES/H-SiO 2 coating with self-cleaning performance, higher defrosting efficiency, and the ability to delay icing, which has great prospects in practical applications.
研究领域:
材料科学
·
表面工程
✓ 已验证
产品关联
DOI
高影响因子
DESALINATION
·
2024
·
IF 8.3
Jinjin Jia,Jinlong Wang,Dachao Lin,Jing Zhao,Hesong Wang,Longfeng Hu,Jiaxuan Yang,Han Zhang,Guibai Li,Heng Liang
Membrane scaling severely hinders practical application of nanofiltration (NF) for brackish water treatment. However, the contributions of residual aluminum ( Al ), especially various species with differing polymerization degrees and sizes, to gypsum scaling remain unclear. Herein, the complex interactions between three Al species (AlCl 3 , Al 13 and Al 30 ) and gypsum scaling were investigated, including surface and bulk crystallization processes. Results demonstrated that Al species adhering to the membrane surface promoted surface crystallization and altered crystal morphology. Notably, the Al 13 species induced the formation of dense, complete rosette crystals causing the most severe flux decline. For bulk crystallization, Al 30 was the primary species to promote nucleation. This promotion resulted from two factors: a lower nucleation energy barrier and the promoted aggregation of small crystals. Furthermore, molecular dynamics (MD) simulations revealed that the inhibition of nucleation due to the competition between Al species and calcium ions at nucleation sites was negligible compared to the strong promotion effect. These findings demonstrated that PACl exhibit higher scaling potential during NF than monomeric Al coagulants. Ultimately, the competition between surface and bulk crystallization determined the final membrane flux decline. This study offers valuable insights into the mechanisms of NF scaling caused by residual Al and guides mitigation strategies.
研究领域:
环境科学
·
水处理
·
膜技术
·
材料科学
✓ 已验证
产品关联
DOI
高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2020
·Vol. 103
·期 11
·6586-6593
·
IF 3.502
Zhilong Fu,Yafei Liu,Bo Zhang,Aimin Chang
The cold sintering process (CSP) has been used for fabricating functional ceramics at a low sintering temperature. In this study, highly dense 0.3CaCeNbWO 8 -0.7LaMnO 3 composite ceramics have been successfully fabricated by CSP. The phase structure, microstructure, and electrical properties of composite ceramics have been investigated. The composite ceramic is mainly composed of a tetragonal CaCeNbWO 8 phase with scheelite structure and an orthorhombic LaMnO 3 phase with perovskite structure. The relative density of composite ceramic is 94.5%, and is higher than that of single phase ceramic. The resistivity of composite ceramic exhibits negative temperature coefficient characteristics, with an aging coefficient less than 2%. Such a sintering methodology is of great significance, since it provides a feasible idea for preparing composite ceramics.
研究领域:
材料科学
·
电子工程
✓ 已验证
DOI
高影响因子
BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
·
2018
·
IF 2.559
Peihai Li,Kun Zang,Yingjie Li,Changshui Liu,Qingjun Ma
Extracellular proteases are often produced as pre-pro-enzyme and then undergo multiple processing steps to mature into the active form. The protease Epp, a virulent factor of Vibrio anguillarum , belongs to this family. Its maturation might be regulated by Ca 2+ via its polycystic kidney disease (PKD) domain, but the molecular mechanism is unknown. Herein, we report the crystal structure of the first PKD domain from V. anguillarum Epp (Epp-PKD1) and its specific Ca 2+ -binding capacity. Epp-PKD1 exists as a monomer , consisting of seven β-strands which form two β-sheets stacking with each other. One Ca 2+ is bound by the residues Asn3, Gln4, Asp27, Asp29, Asp68 and a water molecule with a pentagonal bipyramidal geometry. Incubating the apo Epp-PKD1 with Ca 2+ but not Mg 2+ , Mn 2+ , or Zn 2+ , enhances the thermal and chemical stability of Epp-PKD1, indicating its specific binding to Ca 2+ . Epp-PKD1 shares high similarity in both sequence and overall structure with that of Vibrio cholerae PrtV, a homologous protease of Epp, however, they differ in the oligomeric state and local structure at the Ca 2+ -binding site, suggesting maturation of PrtV and Epp might be differently regulated by Ca 2+ . Likely, proteases may take advantage of the structural diversity in PKD domains to tune their Ca 2+ -regulated maturation process.
研究领域:
生物化学
·
结构生物学
·
微生物学
✓ 已验证
DOI
高影响因子
POLYMER
·
2025
·
IF 4.5
Xiaohuan Bu,Wei Zhao,Xin Li,Wenjie Zhang,Yuancheng Zhang,Ge Shi,Yanjie He,Zhe Cui,Peng Fu,Xinchang Pang,Hong Wu,Xiaomeng Zhang,Minying Liu
Polyamide 66 (PA66) with less entangled structure, high crystallinity and excellent mechanical properties was fabricated in this work by direct solid-state polymerization (DSSP) method. The polymerization process and mechanism of DSSP were systematically investigated. Results demonstrate that DSSP is a transition process from salt crystal directly to polymer crystal, enabling the production of PA66 with a less entangled and highly crystalline structure. DSSP sample exhibits a crystallinity of 51.8% as tested by WAXD, and 59.7% when measured via DSC, surpassing the crystallinity of the majority of PA66 fibers. Furthermore, the sample achieves a maximum melting point of 271.7 °C. Correspondingly, mechanical properties and heat distortion temperature of DSSP sample are also improved. Therefore, this work enhances the in-depth understanding of polymerization mechanism of DSSP, and provides an efficient, scalable approach for fabricating polymers with less entanglement, high crystallinity, and exceptional performance characteristics.
研究领域:
材料科学
·
高分子化学
✓ 已验证
产品关联
DOI
高影响因子
CARBOHYDRATE POLYMERS
·
2020
·
IF 7.182
Qiuqin Lin,Yuxiang Huang,Wenji Yu
In this study, two methods including a common method using high concentration of alkali solution and a mild extraction method at ambient conditions were used to extract cellulose from bamboo. The results showed that two methods affected the initial state of the cellulose. Celluloses obtained by the former was a hybrid of cellulose I and II while the latter was pure cellulose I. However, their heat treatment results indicated that the heat treatment (≤200 °C) would not change the aggregation structure of bamboo cellulose, but it will cause the change of intramolecular and intermolecular hydrogen bonds, and the break of glycosidic bonds in the amorphous region and part of the crystalline region of cellulose. Accordingly, the crystallinity of bamboo cellulose will decrease slightly after heat treatment. Finally, the macroscopic morphology change of bamboo cellulose caused by heat treatment was the thermal expansion in the width direction instead of distort.
研究领域:
材料科学
·
植物学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CERAMICS INTERNATIONAL
·
2019
·
IF 3.45
Cheng Zhang,Runping Li,Jianhua Liu,Guo Chen,Shenghui Guo,Lei Xu,Shijie Xiao,Zhigang Shen
The effects of modification temperature and time on polyacrylonitrile (PAN) fibers under various concentrations of KMnO 4 were studied. Wettability , colouration, chemical structure (Fourier transform infrared spectroscopy), crystal structure (X-ray diffraction), stack domains (D), interlayer spacing (d), microscopic structure (Scanning electron microscopy) and elemental content (energy dispersive spectroscopy) were analysed. Aside from its good hydrophilicity, KMnO 4 at 2 and 4 wt% are beneficial to the modification of PAN fibers. The colouration of the fiber at 80 °C is the most obvious. The clear peak of the pre-oxidised fibers at 2340 cm −1 corresponds to the conjugated structure of MnO 4 –C N. At 4 wt%, the degree of pre-oxidation is too high and the main infrared peak disappears. M 2, 30 has a minimum D of 9.320 nm and 8.258 nm at 2θ = 16.883° and 2θ = 29.673°, respectively, and the fiber crystals are the finest. At a content of 4 wt%, the fibers are axially cracked and crystals appear on the surface. M 2, 30 and M 2, 60 have a close percentage of C element, whereas M 2, 30 has a lower percentage of Mn element. The best modification conditions of KMnO 4 are 2 wt%, 80 °C and 30 min.
研究领域:
材料科学
·
化学工程
✓ 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）