Started in 1985 Semimonthly
ISSN 1005-0302
CN 21-1315/TG
Impact factor:6.155

The journal has been awarded the excellent periodical in China, and its articles are covered by SCI, EI, CA, SA, JST, RJ, CSA, MA, EMA, AIA etc., PASCAL web. ISI web of Science,SCOPUS.

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      17 May 2017, Volume 33 Issue 5 Previous Issue    Next Issue
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    Orginal Article
    Controlling molecular weight of naphthalenediimide-based polymer acceptor P(NDI2OD-T2) for high performance all-polymer solar cells
    Lei Yu, Sun Jianxia, Yuan Jianyu, Gu Jinan, Ding Guanqun, Ma Wanli
    J. Mater. Sci. Technol., 2017, 33 (5): 411-417.  DOI: 10.1016/j.jmst.2016.06.028
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    A widely-used naphthalenediimide (NDI) based electron acceptor P(NDI2OD-T2) with different number-average molecular weight (Mn) of 38 (N2200L), 56 (N2200M), 102 (N2200H) kDa were successfully prepared. The effect of molecular-weight on the performance of all-polymer solar cells based on Poly(5-(5-(4,8-bis(5-decylthiophen-2-yl)-6-methylbenzo[1,2-b:4,5-b’]dithophen-2-yl)thiophen-2-yl)-6,7-difluoro-8-(5-methylthiophen-2-yl)-2,3-bis(3-(octyloxy)phenyl)quinoxaline) (P2F-DE):N2200 was systematically investigated. The results reveal that N2200 with increased Mn show enhanced intermolecular interactions, resulting in improved light absorption and electron mobility. However, the strong aggregation trend of N2200H can cause unfavorable morphology for exciton dissociation and carrier transport. The blend film using N2200 with moderate Mn actually develops more ideal phase segregation for efficient charge separation and transport, leading to balanced electron/hole mobility and less carrier recombination. Consequently, all-polymer solar cells employing P2F-DE as the electron donor and N2200M as the electron acceptor show the highest efficiency of 4.81%, outperforming those using N2200L (3.07%) and N2200H (3.92%). Thus, the Mn of the polymer acceptor plays an important role in all-polymer solar cells, which allows it to be an effective parameter for the adjustment of the device morphology and efficiency.

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    Photovoltaic devices employing ternary PbSxTe1-x nanocrystals
    Zhu Xiangxiang, Liu Zeke, Shi Guozheng, Gu Jinan, Wang Weiwei, Ma Wanli
    J. Mater. Sci. Technol., 2017, 33 (5): 418-423.  DOI: 10.1016/j.jmst.2017.01.018
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    Colloidal quantum dots (CQDs), especially lead chalcogenide CQDs, are regarded as promising materials for the next generation solar cells, due to their large absorption coefficient, excellent charge transport, and multiple exciton generation effect. We successfully synthesized highly-crystalline, monodispersed, well-alloyed PbSxTe1-x nanocrystals via a one-pot, hot injection reaction method. Energy-filtered transmission electron microscopy suggested that the S and Te anions were uniformly distributed in the alloy nanoparticles. The photovoltaic performance of CQD solar cells based on ternary PbSxTe1-x was reported for the first time. The photovoltaic devices using PbSxTe1-x were more efficient than either the pure PbS or the PbTe based devices. In addition, the PbSxTe1-x based devices showed a significantly improved stability than that of the PbTe based devices.

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    Nitrogen- and Oxygen-Containing Porous Ultrafine Carbon Nanofiber: A Highly Flexible Electrode Material for Supercapacitor
    Wei Kai, Kim Kyu-Oh, Song Kyung-Hun, Kang Chang-Yong, Soon Lee Jung, Gopiraman Mayakrishnan, Kim Ick-Soo
    J. Mater. Sci. Technol., 2017, 33 (5): 424-431.  DOI: 10.1016/j.jmst.2016.03.014
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    Herein, we report a simple and effective preparation of ultrafine CNFs (u-CNFs) with high surface area via electrospinning of two immiscible polymers [polyacrylonitrile (PAN) and poly(methyl methacrylate) (PMMA)] followed by calcination at high temperature in an inert atmosphere. Various electrospinning conditions were optimized in detail. Four different kinds of PAN/PMMA ratios (10/0, 7:3, 5:5 and 3:7) were chosen and found that the PAN/PMMA ratio of 3:7 (PAN/PMMA-3:7) is the optimum one. BET analysis showed the specific surface area of the u-CNFs-3:7 was 467.57 m2/g with an excellent pore volume (1.15 cm3 g-1) and an average pore size (9.48 nm): it is about 25 times higher than the conventional CNFs (c-CNFs). TEM and FE-SEM images confirmed the ultrafine structure of the CNFs with a thinner fiber diameter of ~50 nm. The graphitic nature and atomic arrangement of the u-CNFs were investigated by Raman and XPS analyses. For the supercapacitor application, unlike the common electrode preparation methods, the u-CNFs-3:7 was used without any activation, chemical or mechanical modifications. The u-CNFs-3:7 showed a better specific capacitance of 86 F/g in 1 mol/L H2SO4 when compared to pure CNFs. The excellent physicochemical properties make the u-CNFs-3:7 an alternative choice to the existing CNFs for the supercapacitors.

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    White Light Emission Characteristics of Tb3+/Sm3+ Co-Doped Glass Ceramics Containing YPO4 Nanocrystals
    Zhang Zhixiong, Zhang Yuepin, Wang Cheng, Feng Zhigang, Zhang Weihuan, Xia Haiping
    J. Mater. Sci. Technol., 2017, 33 (5): 432-437.  DOI: 10.1016/j.jmst.2016.10.002
    Abstract   HTML   PDF

    The Tb3+/Sm3+ single-doped and co-doped glasses and glass ceramics containing YPO4 nanocrystals have been synthesized by melt quenching method. The structural and luminescent properties of these glass specimens were investigated. Under 375 nm wavelength excitation, the emission spectra combined with blue, green and red bands were observed, which achieved the white light emission. Moreover, the energy transfer between Tb3+ and Sm3+ ions was validated by decay lifetime measurement and energy level diagram. The color coordinates (x = 0.333, y = 0.333), correlated color temperature (5595 K) and the color rendering index (Ra = 80.5) indicated that the glass ceramics were considered to be good lighting source. Hence, the YPO4-based Tb3+/Sm3+ co-doped glass ceramics can act as potential matrix materials for white light-emitting diodes under ultraviolet excitation.

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    Amorphous Cobalt Boron Alloy@Graphene Oxide Nanocomposites for Pseudocapacitor Applications
    Zhang Wei, Du Xiaoli, Tan Yueyue, Hu Jinbo, Li Zhen, Tang Bohejin
    J. Mater. Sci. Technol., 2017, 33 (5): 438-443.  DOI: 10.1016/j.jmst.2016.06.012
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    Amorphous Co-B alloy nanoparticles grown on graphene sheets were synthesized via a chemical reduction approach and successfully used for an application as a pseudocapacitor. This study aims to improve the capacity and cycling stability of amorphous Co-B alloy nanoparticles grown on conductive graphene sheets. The products were characterized by X-ray powder diffraction, scanning electron microscopy, and transmission electron microscopy. As electrode materials for pseudocapacitors, the amorphous Co-B alloy grown on graphene oxide (Co-B@GO) exhibits a high specific capacitance of 460 F g-1, which is nearly 1.5 times greater than that of bare Co-B nanoparticles at 1 A g-1. The specific capacitance preserved 84% of the initial capacitance even after 1000 cycles at a scan rate of 10 m V-1, suggesting its promising potential as pseudocapacitor materials.

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    Morphology-Controlled Synthesis of CeO2 Microstructures and Their Room Temperature Ferromagnetism
    Meng Fanming, Fan Zhenghua, Zhang Cheng, Hu Youdi, Guan Tao, Li Aixia
    J. Mater. Sci. Technol., 2017, 33 (5): 444-451.  DOI: 10.1016/j.jmst.2016.06.018
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    Gear-shape CeO2 microstructures have been synthesized via a facile hydrothermal method with Ce(NO3)3?6H2O as the cerium source, NH4HCO3 as both the precipitator and the carbon source, and cetyltrimethyl ammonium bromide (CTAB) as the surfactant. X-ray diffraction (XRD) inferred that the synthesized CeO2 microstructures exhibited a fluorite structure. The band gap (Eg) of CeO2 samples is larger than that of bulk. X-ray photoelectron spectroscopy (XPS) showed that there are plenty of Ce3+ ions and oxygen vacancies at the surface of CeO2 samples. All the synthesized CeO2 samples exhibited the room temperature ferromagnetism, and the saturation magnetization increases with the increases of lattice parameter and Eg. The room temperature ferromagnetism mechanism of gear-shape CeO2 is mainly attributed to the influence Ce3+ ions.

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    Microstructure and mechanical properties of Mg-4.0Zn alloy reinforced by NiO-coated CNTs
    Yuan Qiuhong, Zeng Xiaoshu, Wang Yanchun, Luo Lan, Ding Yan, Li Dejiang, Liu Yong
    J. Mater. Sci. Technol., 2017, 33 (5): 452-460.  DOI: 10.1016/j.jmst.2016.07.022
    Abstract   HTML   PDF

    Mg-4.0Zn alloy composite reinforced by NiO-coated CNTs (NiO@CNTs) was synthesized by combining ball-milling and a casting process. The yield strength (YS) and elongation to failure of the composite were dramatically increased by 44.9% and 38.6%, respectively, compared to its alloy counterpart. The significantly enhanced mechanical properties of the as-synthesized composite are mainly ascribed to an improved interfacial bond, grain refinement and good dispersion of CNTs in the matrix via. coating NiO on CNTs. It is shown that the NiO-nanolayer on the CNTs significantly enhances the interfacial bonding strength and effectively prevents the agglomeration of CNTs. NiO@CNTs are, therefore, expected to be a highly sustainable and dispersible reinforcement for magnesium matrix composites with superior performance.

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    Plasma electrolytic oxidation of the magnesium alloy MA8 in electrolytes containing TiN nanoparticles
    Mashtalyar D.V., Gnedenkov S.V., Sinebryukhov S.L., Imshinetskiy I.M., Puz’ A.V.
    J. Mater. Sci. Technol., 2017, 33 (5): 461-468.  DOI: 10.1016/j.jmst.2017.01.021
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    The formation of protective multifunctional coatings on magnesium alloy MA8 using plasma electrolytic oxidation (PEO) in an electrolytic system containing nanosized particles of titanium nitride was investigated. Electrochemical and mechanical properties of the obtained layers were examined. It was established that microhardness of the coating with the nanoparticle concentration of 3 g l-1 increased twofold (4.2 ± 0.5 GPa), while wear resistance decreased (4.97 × 10-6 mm3 N-1 m-1), as compared to respective values for the PEO-coating formed in the electrolyte without nanoparticles (2.1 ± 0.3 GPa, 1.12 × 10-5 mm3 N-1 m-1).

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    In Vivo Study on Degradation Behavior and Histologic Response of Pure Magnesium in Muscles
    Chen Shanshan, Tan Lili, Zhang Bingchun, Xia Yonghui, Xu Ke, Yang Ke
    J. Mater. Sci. Technol., 2017, 33 (5): 469-474.  DOI: 10.1016/j.jmst.2016.09.011
    Abstract   HTML   PDF

    When an orthopedics device is implanted into bone injury site, it will contact the soft tissue (skeletal muscle, fascia, ligament etc.) except for bone. Magnesium based biodegradable metals are becoming an important research object in orthopedics due to their bioactivity to promote bone healing. In this study, pure Mg rods with and without chemical conversion coating were implanted into the muscle tissue of rabbits. Implants and their surrounding tissues were taken out for weight loss measurement, cross-sectional scanning electron microscopy observation, elemental distribution analysis and histological examination. The results showed that the chemical conversion coating would increase the in vivo corrosion resistance of pure Mg and decrease the accumulation of calcium (Ca) and phosphorus (P) elements around the implants. For the bare magnesium implant, both Ca and P contents in the surrounding tissues increased at the initial stage of implantation and then decreased at 12 weeks implantation, while for the magnesium with chemical conversion coating, Ca and P contents in the surrounding tissues decreased with the implantation time, but were not significant. The histological results demonstrated that there was no calcification in the muscle tissue with implantation of magnesium for up to 12 weeks. The chemical conversion coating not only increased the in vivo corrosion resistance of pure Mg, but also avoided the depositions of Ca and P in the surrounding tissues, meaning that pure magnesium should be bio-safe when contacting with muscle tissues.

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    Effect of Icosahedral Phase on Crystallographic Texture and Mechanical Anisotropy of Mg-4%Li Based Alloys
    Li C.Q., Xu D.K., Yu S., Sheng L.Y., Han E.H.
    J. Mater. Sci. Technol., 2017, 33 (5): 475-480.  DOI: 10.1016/j.jmst.2016.10.003
    Abstract   HTML   PDF

    Through investigating and comparing the microstructure and mechanical properties of the as-extruded Mg alloys Mg-4%Li and Mg-4%Li-6%Zn-1.2%Y (in wt%), it demonstrates that although the formation of I-phase (Mg3Zn6Y, icosahedral structure) could weaken the crystallographic texture and improve the mechanical strength, the mechanical anisotropy in terms of strength remains in Mg-4%Li-6%Zn-1.2%Y alloy. Failure analysis indicates that for the Mg-4%Li alloy, the fracture surfaces of the tensile samples tested along transverse direction (TD) contain a large number of plastic dimples, whereas the fracture surface exhibits quasi-cleavage characteristic when tensile samples were tested along extrusion direction (ED). For the Mg-4%Li-6%Zn-1.2%Y alloy, typical ductile fracture surfaces can be observed in both “TD” and “ED” samples. Moreover, due to the zonal distribution of broken I-phase particles, the fracture surface of “TD” samples is characterized by the typical “woody fracture”.

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    Mechanical Property, Oxidation and Ablation Resistance of C/C-ZrB2-ZrC-SiC Composite Fabricated by Polymer Infiltration and Pyrolysis with Preform of Cf/ZrB2
    Huang Dong, Zhang Mingyu, Huang Qizhong, Wang Liping, Tong Kai
    J. Mater. Sci. Technol., 2017, 33 (5): 481-486.  DOI: 10.1016/j.jmst.2016.09.003
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    C/C-ZrB2-ZrC-SiC composites were fabricated by polymer infiltration and pyrolysis (PIP) with a preform of Cf/ZrB2. The carbon fibers and the resin carbon were coated with ceramic layer after PIP in the composites. The composite presents a pseudo-plastic fracture due to deflection of cracks and pullout of fibers. The composite has a higher bending strength by this method in comparison with the conventional PIP process due to fewer heat treatment cycles. The static oxidation test shows that the mass loss of the composites is no more than 1% after 20 min oxidation at 1100 °C. The “core-shell” structure between ZrC-SiC ceramic and other phases plays a positive role in preventing the inward diffusion of oxygen. The ablation resistance of the C/C-ZrB2-ZrC-SiC composite samples was tested using a plasma generator. After ablation for 120 s, the mass and linear ablation rates of the composites are 4.65 mg cm-2 s-1 and 2.46 μm s-1, respectively. The short carbon layer shows a better ablation resistance than the nonwoven carbon fabric layer after the ceramic coating is peeled off because of its higher ceramic content.

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    Joining of Cf/SiBCN composite with two Ni-based brazing fillers and interfacial reactions
    Li Wenwen, Chen Bo, Xiong Yi, Xiong Huaping, Cheng Yaoyong, Zou Wenjiang
    J. Mater. Sci. Technol., 2017, 33 (5): 487-491.  DOI: 10.1016/j.jmst.2017.01.032
    Abstract   HTML   PDF

    Cf/SiBCN ceramic composite was joined using Ni-19Cr-10Si (BNi5) and Ni-33Cr-24Pd-3.5Si-0.5B filler alloys at 1170 °C for 10 min. Two kinds of Ni-based filler alloys exhibited good wettability on the Cf/SiBCN composite, with a contact angle of 13° and 4°, respectively. The microstructures of the brazed joints were investigated by electron-probe microanalysis (EPMA), and three-point bend test was conducted for the joints at room temperature. When being brazed with BNi5 filler alloy, no evident reaction layer was observed at the surface of the joined composite, and the joint microstructure was characterized by Ni2Si matrix with scatteringly distributing mixture compounds of Cr23C6, Ni2Si and CrB. While Ni-Cr-Pd(Si,B) brazing alloy was used, a Cr23C6 reaction layer with a thickness of 11 μm was formed at the surface of the base composite. In the central part of the brazed joint, the phases were composed of Ni(Cr,Si) solid solution and complex compounds including Pd2Si, (Ni,Pd)2Si and Ni-B. The strength of Cf/SiBCN joint brazed with BNi5 filler alloy was 62.9 MPa at room temperature, whereas that with Ni-Cr-Pd(Si,B) filler alloy was at the same level.

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    Interfacial Structure and Formation Mechanism of Ultrasonic-assisted Brazed Joint of SiC Ceramics with Al-12Si Filler Metals in Air
    Chen Xiaoguang, Xie Ruishan, Lai Zhiwei, Liu Lei, Yan Jiuchun, Zou Guisheng
    J. Mater. Sci. Technol., 2017, 33 (5): 492-498.  DOI: 10.1016/j.jmst.2016.03.016
    Abstract   HTML   PDF

    Ultrasonic-assisted brazing of SiC ceramics was performed by filling with an Al-12Si alloy at a low temperature of 620 °C in air. The interfacial characteristics and formation mechanism were investigated. The joint shear strength reached 84-94 MPa using the ultrasonic time of 2-16 s. The fracture morphology showed that the fracture path initiated and propagated in the joint alloy. The thin film of amorphous SiO2 that formed on the SiC surface was non-uniformly decomposed and diffused into the liquid Al-12Si alloy under the cavitation erosion effect of ultrasound. Abnormal isolated blocks of Al2SiO5 compounds formed at the interface between Al-12Si and a thicker SiO2 layer formed during the thermal oxidation treatment of the SiC ceramic. The SiO2 layer on the SiC ceramic did not hinder or impair the wetting and bonding process, and a stronger bond could form between Al-12Si and SiO2 or SiC in ultrasonic-assisted brazing.

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    Prediction of Dendrite Orientation and Stray Grain Distribution in Laser Surface-melted Single Crystal Superalloy
    Wang Guowei, Liang Jingjing, Zhou Yizhou, Jin Tao, Sun Xiaofeng, Hu Zhuangqi
    J. Mater. Sci. Technol., 2017, 33 (5): 499-506.  DOI: 10.1016/j.jmst.2016.05.007
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    A vectorization analysis technique for crystal growth and microstructure development in single-crystal weld was developed in our previous work. Based on the vectorization method, crystal growth and stray grain distribution in laser surface remelting of single crystal superalloy CMSX-4 were investigated in combination of simulations with experimental observations. The energy distribution of laser was taken into consideration in this research. The experimental results demonstrate that the simulation model applies well in the prediction of dendrite growth direction. Moreover, the prediction of stray grain distribution works well except for the region of dendrites growing along the [100] direction.

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ISSN: 1005-0302
CN: 21-1315/TG
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