Journal of Nanomaterials
·
2018
·Vol. 2018
·期 1
·1634814
·
IF 2.207
Lianbing Zhong,Guihong Geng,Yujin Wang,Feng Ye,Limeng Liu
A fully dense TaC ceramic was prepared by hot pressing using 10 mol% ZrC plus 5 mol% Cu as a sintering aid. Formation of (Ta, Zr)C solid solution (ss) by reaction between TaC and ZrC facilitated densification. Addition of Cu refined the microstructure and consequently improved flexural strength of the TaC ceramics. TEM investigation found ubiquitous precipitation of nanocrystallites at multigrain conjunctions. The nanocrystallites were (Ta, Zr)C solid solution with uniform dispersion in an oxygen-rich glassy matrix. Although formation of nanoprecipitates may not much affect the mechanical properties of the TaC ceramic, the structure suggested a new type of nanoceramic worth further research.
研究领域:
材料科学
·
陶瓷学
·
固态化学
·
显微结构分析
·
复合材料
✓ 已验证
DOI
高影响因子
Journal of Materials Research and Technology-JMR&T
·
2023
·
IF 6.4
Songtong Xuan,Yuming Tian,Xiangchen Kong,Jianying Hao,Xiaojun Wang
The tuning of the properties of MgAl 2 O 4 -based materials has aroused great attention in the field of engineering technology. Along these lines, magnesia and alumina were used as raw materials to prepare spinel by the solid-phase sintering method at 1500–1600 °C. Particularly, the impacts of the different MgO/Al 2 O 3 molar ratios on the microstructural densification, sintering process and mechanical property of the fabricated materials were systematically studied. The results showed that the stoichiometric spinel with the highest concentration of ion diffusion possessed the best densification. And the magnesium-rich spinel displayed the better densification following with the formation of solid-solution, while the aluminum-rich spinel exhibited the worst ability in forming the solid-solution. Moreover, the different molar ratios changed the microstructure of the spinel, which induced the optimal sintering temperature of stoichiometric spinel to be at least 50 °C below that of the others. Specifically, in stoichiometric spinel, spinel grains grew up and formed obvious structure, which made the sintering process arrive at the end point and made the performance reach the best. Specifically, the flexural strength was 112.62 MPa and apparent porosity was 0.44%. However, no grown or developed spinel grains were observed for magnesium-rich/aluminum-rich spinels, which delayed the sintering process.
研究领域:
材料科学
·
无机非金属材料
·
陶瓷工艺学
·
固态化学
·
结构陶瓷
✓ 已验证
DOI
高影响因子
JOURNAL OF THE CHINESE CHEMICAL SOCIETY
·
2017
·Vol. 64
·期 4
·412-419
·
IF 0.935
Xiu-Yan Dong,Sunday Folaranmi Akogun,Wei-Min Zhou,Wen-Kui Dong
A new tetranuclear Zn(II) complex, [{Zn(L)(μ-OAc)Zn(H 2 O)} 2 ], based on an asymmetrical salamo-type bisoxime chelating ligand H 3 L (6-hydroxy-4′-chloro-2,2′-[ethylenediyldioxybis(nitrilomethylidyne)]diphenol) was synthesized and characterized by elemental analyses, differential thermal methods, single-crystal X-ray crystallography, and IR, UV–vis, and fluorescence spectra. The Zn(II) complex crystallizes in the triclinic system, space group P -1 with cell parameters a = 9.0742(6) Å, b = 11.8225(5) Å, c = 12.4182(8) Å, Z = 2, V = 1212.56(12) Å 3 , R 1 = 0.0572, and wR 2 = 0.1734. The environment of the tetranuclear Zn(II) complex is penta-coordinated having a slightly distorted trigonal bipyramidal geometry. Moreover, a 1D chain supramolecular structure is formed along the c -axis by the intermolecular C1–H1B⋯O14 hydrogen bonds; in the same manner, C2–H2C⋯Cg2 functions in the formation of supramolecular structures along the a -axis of the 1D chain. A 2D supramolecular structure along the ac plane extends infinitely under the force of intermolecular hydrogen bonds. Differential scanning calorimetry-thermogravimetry thermal analysis provides evidence of the coordination of Zn(II) atoms to the ligand H 3 L. The Zn(II) complex shows intense photoluminescence with a maximum emission at ~453 nm upon excitation at 360 nm.
研究领域:
无机化学
·
配位化学
·
超分子化学
·
材料化学
·
分析化学
·
物理化学
·
晶体学
✓ 已验证
DOI
高影响因子
POLYMER
·
2021
·
IF 4.43
Lu Shi,Wei Liu,Yanhu Xue,Mei Hong,Xiangling Ji
Temperature Rising Elution Fractionation (TREF) is effective for separating polyolefin resins according to crystallizability. A relatively low isothermal crystallization temperature is necessary to fractionate poly(1-butene) (PB-1) resin because of its slow crystallization kinetics . This study aims to investigate the influence of isothermal crystallization temperature of TREF on the fractionation and chain microstructure of eluted fractions for one poly(1-butene-co-ethylene) with 5.8 mol% ethylene. The resin is fractionated using P-TREF under four different isothermal crystallization temperatures, i.e. 0 °C, −5 °C, −10 °C, and −30 °C, and then the fractions are characterized by high-temperature gel permeation chromatography (HT-GPC), 13 C nuclear magnetic resonance spectroscopy ( 13 C NMR), and differential scanning calorimetry (DSC) to acquire their chain microstructure information. The isothermal crystallization temperature significantly affects the nucleation and growth of the crystals, which consequently results in differences in the relative content of eluted fractions. With the decrease of isothermal crystallization temperature from 0 °C to −30 °C, the copolymer is fractionated more effectively since fractions are more evenly distributed among elution temperatures rather than concentrated at lower elution temperatures. Furthermore, the isothermal crystallization temperature influences the chain microstructure of fractions obtained at the same elution temperature, which are different in ethylene content, isotacticity, and average sequence length. The distribution of ethylene content and isotacticity becomes broader with the decrease in isothermal crystallization temperature. Lower isothermal crystallization temperature is conducive to effective separation of the fractions with weak crystallizability. These results are of great significance for the selection of fractionation conditions and chain microstructure analysis of poly(1-butene-co-ethylene) resins.
研究领域:
高分子化学
·
材料科学
·
聚合物表征
·
热分析
·
核磁共振波谱学
✓ 已验证
DOI
高影响因子
IONICS
·
2019
·Vol. 26
·期 1
·263-272
·
IF 2.289
Luo X. Y.,Meng B.,Xia Z. D.,Chen Q. B.,Dong D. Z.,Zhao M. Y.
In order to investigate the effects of Na 2 CO 3 /ZnO co-addition on the sinterability and electrical conductivity of BaZr 0.1 Ce 0.7 Y 0.1 Sc 0.1 O 3-δ (BZCYSc) ceramic, Na 2 CO 3 and ZnO were added and BZCYSc/ZnO/Na 2 CO 3 ceramic was prepared by mechanical ball milling and high-temperature sintering in air. The crystalline structure, micro-morphology, chemical composition, density, and electrical conductivity of the sintered ceramics were characterized by XRD, SEM, EDS, Archimedes method, and electrochemical impedance spectrum, respectively. The grains size of BZCYSc-2%ZnO-5%Na 2 CO 3 is about 2.5~5 μm. Na 2 CO 3 /ZnO co-addition is beneficial to improve the sinterability and electrical conductivity of BZCYSc. The sintering temperature of BZCYSc can be lowered from 1550 to 1350 °C when 2 mol%ZnO is added. At 550 °C, the electrical conductivities of BZCYSc-2%ZnO-10%Na 2 CO 3 and BZCYSc are 1.90 × 10 −3 S/cm and 1.81 × 10 −3 S/cm. The activation energies of BZCYSc and BZCYSc-2%ZnO-10%Na 2 CO 3 are 0.7529 eV and 0.5641 eV, respectively.
研究领域:
材料科学
·
无机非金属材料
·
固态离子学
·
能源材料
·
陶瓷工程
✓ 已验证
DOI
高影响因子
APPLIED SURFACE SCIENCE
·
2017
·
IF 3.387
Yan Zhao,Yang Gao
The microstructure of plasma-sprayed nanostructured yttria-stabilized zirconia (YSZ) coatings may change during high-temperature exposure, which would influence the coating performance and service lifetime. In this study, the phase structure and the microstructural evolution of 3YSZ (zirconia-3 mol% yttria) and 5YSZ (zirconia-5 mol% yttria) nanostructured coatings were investigated by means of sintering at 1400 °C for 50–100 h. The microhardness, elastic moduli, and thermal shock cycles of the 3YSZ and 5YSZ nanostructured coatings were also investigated. The results showed that the redistribution of yttrium ions at 1400 °C caused the continuous increase of monoclinic-phase zirconia, but no obvious inter-splat cracking formed at the cross-sections, even after 100 h. Large voids appeared around the nanoporous zone because of the sintering of nanoscale granules upon high-temperature exposure. The microhardness and elastic moduli of the nanostructured coatings first increased and then decreased with increasing sintering times. The growth rate of the nanograins in the 3YSZ coating was lower than that in 5YSZ, which slowed the changes in 3YSZ coating porosity during sintering. Although the 3YSZ coating was prone to monoclinic phase transition, the experimental results showed that the thermal shock resistance of the 3YSZ coating was better than that of the 5YSZ coating.
研究领域:
材料科学
·
表面工程
·
陶瓷涂层
·
热障涂层
·
高温材料
✓ 已验证
DOI
高影响因子
WATER RESEARCH
·
2024
·
IF 11.4
Jie Liu,Kexin Zhang,Xin Liu,Qiyong Xu,Weiyi Li
Despite being recognized as a promising technique for treating high salinity water, membrane distillation (MD) has been plagued by the scaling of sparingly soluble salts. The growth of crystals can not only create additional resistance to evaporating water at the feed-membrane interface, but also alter the hydrophobic network to bridge the feed and distillate (i.e., result in the phenomenon of wetting). When recognizing the uncertain behaviors of calcium sulfate (CaSO 4 ) scaling in MD, this study was motivated to ascertain whether the crystal-membrane interactions could be dependent on the variation in crystalline morphology. In particular, optical coherence tomography (OCT) was employed to characterize the scaling-induced wetting via a direct-observation-through-the-membrane (DOTM) mode, which mitigated the effects of developing an external scaling layer on resolving the crystal-membrane interactions. The improved in-situ characterization suggests that the crystalline morphology of CaSO 4 could be effectively regulated by varying the stoichiometry of crystallizing ions; the richness of calcium in the aqueous environment for crystallization would be in favor of weakening the crystal-membrane interactions. The stoichiometry-dependent growth of CaSO 4 crystals can be exploited to develop an effective strategy for preventing the hydrophobic network from being wetted or irreversibly damaged.
研究领域:
环境科学
·
膜科学与技术
·
化学工程
·
水处理技术
·
材料表征
·
结晶过程
✓ 已验证
DOI
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2019
·
IF 2.781
Faqiang Shi,Limeng Liu,Zhaoping Hou,Guihong Geng,Yujin Wang
Tantalum carbide ceramics with an overall composition of TaC 0.6 were prepared by hot pressing at 1700 °C for 1 h under 30 MPa pressure with fcc TaC and bcc Ta powder as starting materials. Effects of adding 0–30 mol% Cu on densification, phase formation, microstructural evolution , mechanical properties and electrical conductivity of the obtained composite ceramics were investigated. Full density could be reached at 20 mol% Cu addition and above. Reactions between TaC and Ta resulted in the final phases of hexagonal Ta 2 C and rhombohedral ζ-Ta 4 C 3-x . Plate-shaped ζ laminate grew in both TaC and Ta 2 C and consequently had their sizes confined by the parental grains. Addition of 20–30 mol% Cu could significantly grow the intermediate Ta 2 C grains, hence controlling length of the ζ laminates precipitated in them to form bimodal microstructures consisting of large grains. The 20 mol% Cu composition had a better flexural strength (706 ± 46 MPa) and fracture toughness (9.2 ± 1.7 MPa m 1/2 ). Electrical resistivity at room temperature of the composites decreased with Cu content from 1.03 μΩ m at 0 mol% addition to 0.12 μΩ m at 30 mol% Cu.
研究领域:
材料科学
·
陶瓷学
·
复合材料
·
粉末冶金
·
结构陶瓷
·
物理化学
·
固态化学
✓ 已验证
DOI
高影响因子
CONSTRUCTION AND BUILDING MATERIALS
·
2024
·
IF 7.4
Kai Luo,Wensheng Zhang,Jiayuan Ye,Jun Li,Zhongyuan Lu,Xuehong Ren
The physical and microscopic properties of γ-C 2 S and β-C 2 S under hydration, carbonation , and hydration–carbonation cycle reactions were investigated. The hydration–carbonation cycle reaction facilitated the carbon sequestration of C 2 S, and the generation of CaCO 3 filled the pores of the matrix and enhanced the matrix density in the carbon fixation reaction process. In the subsequent hydration and reaction process, the formation of hydration products increased the number of pores in the matrix and reduced the matrix density. Post-hydration, γ-C 2 S slurry became powder and had no mechanical strength . However, after carbonation reaction and two carbonation–hydration cycles, γ-C 2 S exhibited better mechanical properties than β-C 2 S.
研究领域:
材料科学
·
硅酸盐化学
·
建筑材料
·
碳捕集与封存
·
无机非金属材料
✓ 已验证
DOI
高影响因子
CERAMICS INTERNATIONAL
·
2024
·Vol. 51
·期 14
·18384-18391
·
IF 5.1
Fangliang Shen,Bingheng Sun,Tao Feng,Conghui Huang,Yin Hang,Benxue Jiang,Long Zhang,Jintai Fan
This work aims to fabricate the Yb:LuScO 3 sesquioxides transparent ceramics for use in ultrafast and ultrashort laser technology. 1 at.% Yb:LuScO 3 nanopowders were fabricated using the glycine-nitrate process. ZrO(NO 3 ) 2 was selected as the precursor of ZrO 2 which functions as a sintering aid. Yb:LuScO 3 transparent ceramics with different ZrO 2 content were fabricated by vacuum sintering at 1780 °C and HIPing at 1650 °C, among which the ceramic with 7 at.% ZrO 2 showed the highest transmittance, reaching 81 % at 2000 nm. The ceramic achieved a maximum output power of 1.5 W at 1038 nm with a slope efficiency of 34.8 % and tunable wavelength range exceeding 22 nm. The results demonstrated that Yb:LuScO 3 transparent ceramics can be considered as promising materials in 1 μm solid-state laser applications.
研究领域:
材料科学
·
光学工程
·
固体激光技术
·
无机非金属材料
·
先进陶瓷
✓ 已验证
DOI
高影响因子
MATERIALS LETTERS
·
2020
·
IF 3.204
Yun Zhang,Shihua Ding,Tianxiu Song,Yingchun Zhang
CoSnNb 2 O 8 ceramic with medium-permittivity was initially generated. Compositionally induced phase formation was identified by X-ray diffraction. Tetragonal rutile-type CoSnNb 2 O 8 was obtained from the reaction of SnO 2 with intermediate phase CoNb 2 O 6 . Both the dielectric constant ε r and quality factor Q × f initially increased with the sintering temperature, reaching the maxima at around 1225 °C, and declined thereafter. They were discussed based on the ionic polarizabilities and packing fraction, respectively. The temperature coefficient of resonant frequency τ f primarily depended on the Nb-site bond valence, as well as oxygen octahedra distortion. When sintered at 1225 °C, the CoSnNb 2 O 8 ceramic exhibited optimum properties with ε r = 31.8, Q × f = 43,000 GHz, and τ f = 35.01 ppm/°C.
研究领域:
材料科学
·
无机非金属材料
·
介电物理
·
功能陶瓷
·
微波材料
✓ 已验证
DOI
高影响因子
OPTICAL MATERIALS
·
2023
·
IF 3.9
Yibo Zhang,Shen Wang,Biao Liu,Yan Hao
MgAl 2 O 4 :Cr 3+ transparent ceramics were prepared by a hot-pressed sintering process with Y 2 O 3 and La 2 O 3 as sintering aids, and the effects on the microstructure, densification, optical transmission, and photoluminescent properties were investigated. The sintering aids of Y 2 O 3 and La 2 O 3 enhanced the relative density, reaching 99.33% with 2.4 wt% Y 2 O 3 and 99.24% with 0.8 wt% La 2 O 3 . La 2 O 3 also inhibited abnormal grain growth and obtained ceramics with uniform grain size. In addition, the optical transmission was also improved with Y 2 O 3 and La 2 O 3 as sintering aids. The transmission of the ceramic with 2.4 wt% Y 2 O 3 exceeded 78% in the region of 700–6000 nm and reached 83% at 1450 nm. Moreover, Y 2 O 3 and La 2 O 3 both contributed to improving the quantum yield of the ceramics, especially for Y 2 O 3 , and the quantum yield was about 0.354, which was approximately two times higher than that without R 2 O 3 . In summary, La 2 O 3 was helpful for improving sintering process, inhibiting grain growth, and homogenizing the grain size, while Y 2 O 3 was significant for enhancing the optical and photoluminescent properties.
研究领域:
材料科学
·
无机非金属材料
·
功能陶瓷
·
光电子学
·
固态发光材料
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）