Research progress in ZnO single-crystal: growth,scientific understanding,and device applications

Zinc oxide, a wide band-gap semiconductor, has shown extensive potential applications in high-efficiency semiconductor photoelectronic devices, semiconductor photocatalysis, and diluted magnetic semiconductors. Due to the undisputed lattice integrity, ZnO single crystals are essential for the fabrication of high-quality ZnO-based photoelectronic devices, and also believed to be ideal research subjects for understanding the underlying mechanisms of semiconductor photocatalysis and diluted magnetic semiconductors. This review, which is organized in two main parts, introduces the recent progress in growth, basic characterization, and device development of ZnO single crystals, and some related works in our group. The first part begins from the growth of ZnO single crystal, and summarizes the fundamental and applied investigations based on ZnO single crystals. These works are composed of the fabrication of homoepitaxial ZnO-based photoelectronic devices, the research on the photocatalysis mechanism, and dilute magnetic mechanism. The second part describes the fabrication of highly thermostable n-type ZnO with high mobility and high electron concentration through intentional doping. More importantly, in this part, a conceptual approach for fabricating highly thermostable p-type ZnO materials with high mobility through an integrated three-step treatment is proposed on the basis of the preliminary research.     

Effect of heating rate on the electrochemical performance of MnO X @CNF nanocomposites as supercapacitor electrodes

Carbon nanofibers （CNFs） and MnOjc@CNF nanocomposites （MCNFs） are fabricated by electrospin- ning and investigated as free-standing electrodes for sup- ercapacitor. This work presents the effect of heating rate during carbonization on the electrochemical behavior of the as-prepared MCNFs electrodes in 6 mol/L KOH elec-trolyte. Results show that the MCNFs electrodes carbon- ized by relatively slower heating rate exhibit higher specific capacitance. The electronic conductivity of the slow heated MCNFs electrodes is better than that of the fast heated electrodes due to the better crystallinity of the MnOx nanoparticles and the graphitic carbon layers forming on the surface of the Mn-loaded CNFs. These MCNFs electrodes demonstrate elevated rate capability and improved cycling performance without adding any polymer binder or electronic conductor.     

Structural phase transition and metallization in compressed SrC_2

The structural, dynamical, and electronic properties of compressed Sr C2 were systematically investigated up to 200 GPa by using ab initio method. Three new phases are obtained by means of evolutionary algorithm. The confirmed most stable structure has C2/c symmetry at zero pressure, which transforms into an orthorhombic Cmcm phase at 4.5 GPa, followed by another orthorhombic Immm phase, which is stabilized at wide pressure range of 21.5–123.5 GPa, and then transformed into Mg B2-type phase（space group, P6/mmm）. Although Sr C2 has similar structural transformation to that of compressed Ca C2, Sr C2 holds small electron–phonon coupling,which leads to its low superconducting critical temperature（only 1.8 K）.     

Retrieval of column-averaged volume mixing ratio of CO2 with ground-based high spectral resolution solar absorption

The total column-averaged volume mixing ratio of atmospheric carbon dioxide （Xco2） has been retrieved with high spectral resolution solar absorption data obtained from ground-based Fourier transform spectrometer （FTS） measurements at Xichong, a coastal site in the district of Shenzhen in southern China. Based on differential optical absorption spectroscopy （DOAS） theory, the Xco2 was retrieved by finding the best match of observed high spectral resolution solar absorption data and monochromatic radia- tion transfer model calculations. The averaged Xco2 in the whole observation period was about 394.9 ppm. The uncertainty of the retrieval was estimated to be 2.0 ppm （0.51%） by comparing retrievals at two bands. The preliminary results show that Xc% retrieved by this method can be used to validate satellite remote sensing of Xco2.     

Predicting Equation for Adjusting Glass Temperature of Binder Used for P/M Warm Compaction Processing

Based on considering both negative effect of compacting pressure on glass temperature (T_g) and positive effect of plasticizer added into organic binder, a mathematical equation for adjusting T_g of binder used for warm compaction processing is given. The equation shows that mass fraction of plasticizer need for lowering T_g is function of compacting plessure. The rationality of the equation for warm compaction processing is also discussed.     

Erratum to: Electrical conductivity of molten LiF–DyF3–Dy2O3–Cu2O system for Dy–Cu intermediate alloy production

Erratum to:International Journal of Minerals, Metallurgy and Materials Volume 26, Number 6, June 2019, Page 701https://doi.org/10.1007/s12613-019-1775-z The acknowledgements of this article unfortunately contained a mistake. The grant number of the National Natural     

Effects of elemental Sn on the properties and inclusions of the free-cutting steel

A new environment-friendly free-cutting steel alloyed with elemental Sn (Y20Sn) was developed to meet the requirements of machinability and mechanical properties according to GB/T8731-1988. The machinability of the steel is enhanced by the segregation of elemental Sn at grain boundaries. The effect of Sn segregation on intergranular brittle fracture at normal cutting temperature from 250℃ to 400℃ is confirmed. The formation mechanism of main inclusions MnS is influenced by the presence of Sn and the attachment of Sn around MnS itself as a surfactant, and this mechanism also explains the improvement in machinability and mechanical properties of the steel. In the steel, the relevant inclusions are mainly spherical or axiolitic, and are uniformly distributed in small volume. Such inclusions improve the machinability of the steel and do not impair the mechanical properties as well. Experimental results demonstrate that the appropriate content of Sn in the steel is 0.03wt% to 0.08wt%, and the remaining composition is close to that of standard Y20 steel.     

Fabrication and properties of foam geopolymer using circulating fluidized bed combustion fly ash

In recent years, circulating fluidized bed combustion fly ash (CFA) is used as a raw material for geopolymer synthesis. Hydrogen peroxide was employed as a foaming agent to prepare CFA-based foam geopolymer. The particle distribution, mineral composition, and chemical composition of CFA were examined firstly. Geopolymerization products were characterized by mechanical testing, scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray fluorescence (XRF). The CFA-based foam geopolymer was successfully fabricated with different contents of hydrogen peroxide and exhibited uncompleted alkali reaction and reasonable strength with relative low atomic ratios of Si/Al and Si/Na. Type-C CFA in this research could be recycled as an alternative source material for geopolymer production.     

Performance improvement of car body structure in 100 % frontal impact

During the 100%front impact,all the parts of front car will participate in the course;the crash stiffness of bodywork will also reach the peak.During the crash,rational structure of bodywork can resist the distortion,absorb more energy and get better mode of distortion and low deceleration rate,so as to meet the performance of crash safety.The paper mainly makes optimization analysis based on the problems of front side rails,subframe,firewall,and optimization cases are confirmed which can decrease the intrusion and deceleration rate of the whole car.The structure of bodywork after optimization can meet the performance of crash safety.     

A real-time data smoothness method based on xPC-Target

A method of real-time data smoothness which is applied in a hardware-in-the-loop (HIL) simulation platform for a plug-in hybrid electric vehicle synthetical power device is described. The input signal of the platform comes from a AC/DC switch power with output containing noises. A linear slide average arithmetic is applied to smooth the noises. To average a certain number input sample signals, this method can decrease the noises voltage level, which meet the requirement of the simulation platform. The efficiency and signal delay time are presented to describe the result of this method, and a statistical index is used to judge the arithmetic's efficiency. The tests results show that the arithmetic fit the requirement of the HIL simulation platform.