Coordination and bond properties of Al and Si ions in system of Al_2O_3-SiO_2 melts

1　ＩＮＴＲＯＤＵＣＴＩＯＮＴｈｅｐｒｏｐｅｒｔｉｅｓｏｆｂｉｎａｒｙｓｌａｇｓｙｓｔｅｍｏｆＡｌ2 Ｏ3 ＳｉＯ2 ａｒｅｂａｓｉｃｂａｃｋｇｒｏｕｎｄｋｎｏｗｌｅｄｇｅｆｏｒｍｅｔａｌｌｕｒ ｇｉｓｔ .Ｂｕｔｕｐｔｏｎｏｗ ,ｔｈｅｍｏｓｔｍａｊｏｒｉｔｙｏｆｋｎｏｗｌｅｄｇｅａｂｏｕｔｓｌａｇｉｓｓｔｉｌｌｂａｓｅｄｏｎｅｘｐｅｒｉｅｎｃｅ .Ｉｎｏｒｄｅｒｔｏｓｙｓｔｅｍｉｚｅａｎｄｔｈｅｏｒｉｚｅｔｈｅｋｎｏｗｌｅｄｇｅｏｆｐｒｏｐｅｒｔｉｅｓｏｆｓｌａｇ ,ｃｏｍｐｌｅｔｅａｎｄｆｕｒｔｈｅｒｕ…     

聚合物AY在硅酸二钙-铝酸钠溶液体系中的吸附和分布

本文通过研究聚合物AY在硅酸二钙-铝酸钠溶液体系中的吸附规律,发现其吸附类型为饱和吸附.达到吸附饱和的时间为40min,饱和吸附量为2.17rng.g-1;聚合物AY在硅酸二钙上的吸附行为属"L"型等温线,附合Lang-muir单分子层吸附模型,为化学吸附为主.同时,考察了聚合物AY在熟料溶出过程中液固分离时的分布走势,结果表明,用含有80mg.L-1～160mg.L-1聚合物AY的铝酸钠溶液溶出熟料时.70%的聚合物AY吸附在固相上带出系统.残留在铝酸钠溶液中的量较少.     

Modelling structural changes of a molten Cu55 cluster on cooling by molecular dynamics

应用分子动力学研究了一个熔融Cu55团簇冷却过程中变为二十面体的结构变化. 根据原子密度分布函数和对分布函数随温度变化的分析表明, 在降温过程中由于原子之间连续地交换位置, 团簇结构发生了三个阶 段的变化: 首先形成三壳层结构, 继之初步形成四壳层结构, 并在团簇内部开始形成由13个原子组成的二十面 体结构, 最终形成原子分布于4个壳层内具有二十面体结构的Cu$_{55}$团簇. 模拟中由原子密度分布函数确定了不同壳层的原子位置.     

Effects of Na-substitution on structural and electronic properties of Li2CoSiO4 cathode material

Na-substituted dilithium orthosilicate Li2CoSiO4 was investigated by performing density functional theory calculations within the GGA+U framework. The effects of Na-substitution on the electronic structures and structural properties of Li2CoSiO4 were presented. The results show that the Na-substitution on Li sites in Li2CoSiO4 induces a lowering of the conduction bands and a narrowing of the band gap, which could be helpful for enhancing the electronic conductivity. On the other hand, the Na-substitution on the Li ions in Li2CoSiO4 leads to the expansion of interlayer space of the adjacent corrugated layers. This lattice expansion effect would benefit the Li ion diffusion.     

Identification of structural entities in NdF3-LiF melts with cryoscopic method

Nd-F species in NdF3-LiF melts were studied using cryoscopic method.Liquidus temperatures of melts of various compositions were determined by differential thermal analysis(DTA).Based on the different model calculations,NdF4- was identified as the most likely Nd-F entity in the melts in which the mole fraction of NdF3 was lower than 20%,considering only one single Nd species in the melt,and which was formed in accordance with Temkin model or Flood model.Then,activities of different components in the melts were researched.The results show that activity of LiF decreases,and that of NdF3 increases with increasing the mole fraction of NdF3.The value of activity coefficient of NdF3 is higher than 1,and that of LiF is lower than 1.     

KOH处理对ZnO纳米棒阵列结构及光电性能的影响(英文)

采用简单的化学沉积结合KOH碱刻蚀的方法,在导电玻璃(FTO)上生长ZnO纳米棒阵列(ZnONRs)。用X射线衍射(XRD)、扫描电子显微镜(SEM)、电流—电压(I—V)曲线对所得样品的晶型、形貌及光电性能进行测试,结果表明:ZnONRs呈纤铅矿型;ZnONRs的形貌及光电性能与KOH的浓度及刻蚀时间密切相关,经0.1mol/LKOH刻蚀1h后可得到排列高度有序且分布均匀的ZnONRs;KOH刻蚀后的ZnONRs与未刻蚀前高密度的ZnONRs相比,其光学性能得到提高。0.1mol/LKOH刻蚀1h的ZnONRs作为太阳能电池的光阳极,其光电转换效率、短路电流、开路电压较未刻蚀的ZnONRs分别提高了0.71%、2.79mA和0.03V。     

Local structure of calcium silicate melts from classical molecular dynamics simulation and a newly constructed thermodynamic model

The distributions of local structural units of calcium silicate melts were quantified by means of classical molecular dynamics simulation and a newly constructed structural thermodynamic model. The distribution of five kinds of Si-O tetrahedra Q_i from these two methods was compared with each other and also with the experimental Raman spectra, an excellent agreement was achieved. These not only displayed the panorama distribution of microstructural units in the whole composition range, but also proved that the thermodynamic model is suitable for the utilization as the subsequent application model of spectral experiments for the thermodynamic calculation. Meanwhile, the five refined regions mastered by different disproportionating reactions were obtained. Finally, the distributions of two kinds of connections between Q_i were obtained, denoted as Q_i-Ca-Q_j and Q_i-[O_b]-Q_j, from the thermodynamic model, and a theoretical verification was given that the dominant connections for any composition are equivalent connections.     

Na2O-B2O3熔体结构的分子动力学模拟

用分子动力学方法进行了熔融（１０７３Ｋ）Ｎａ２Ｏ０－Ｂ２Ｏ３的计算机模拟分析和讨论了不同Ｎａ２Ｏ浓度下,计算所得径向分布函数、配位数、振动态密度随Ｎａ２Ｏ浓度变化的特点,并与实验结果作了比较。振动态密度的计算值与Ｖｏｒｏｎｋｏ等给出的Ｒａｍａｎ谱上（Ｂ３Ｏ６）环展成（ＢＯ２）３链的振动峰位相符合。随着Ｎａ２Ｏ浓度的增加,Ｂ－Ｂ第一邻近距离有微小的增加。而Ｂ－Ｏ第一邻近距离只有极小的增加。另一方面,     

SiO_2表面覆盖剂对铝合金熔体直接氧化生长的影响

以Lanxide材料的成形工艺控制为目标 ,研究了SiO2 表面覆盖剂在铝合金熔体直接氧化生长过程中的作用。结果表明有效促进Al2 O3/Al复合材料生长的SiO2 加入量为 1～ 6 g/dm2 。SiO2 能够显著促使材料近平面生长 ,形成细化胞状晶团和提高组织均匀度 ;在覆盖SiO2 的条件下 ,温度升高 ,生长速度加快的同时 ,材料宏观生长表面趋于平整 ,但温度过高会对组织致密度产生不利影响     

Ni-Al含能结构材料的制备和性能研究

以Ni粉和Al粉(摩尔比1:1)为原料,采用冷压-烧结法制备了Ni-Al含能结构材料。研究了烧结温度对Ni-Al含能结构材料界面扩散、力学性能、起始反应温度和能量密度等的影响。结果表明：烧结温度的提高,增加了Ni-Al颗粒间界面扩散速率,从而使含能结构材料界面粘合强度增大,拉伸和压缩强度提高,同时,能量密度降低;当烧结温度为550℃时,可获得强度和能量密度俱佳的含能结构材料,其拉伸和压缩强度分别为66.0 MPa和294.6 MPa,能量密度为436.1 J/g。     

超细镍纳米线拉伸性能的温度和应变率相关性的分子动力学研究

基于EAM势,采用分子动力学方法对超细镍纳米线（直径分别为3．94、4．95和5．99nm）在（100）晶向的拉伸性能进行研究,并对其温度相关性和拉伸应变率相关性进行探讨。结果表明：弹性模量和屈服强度随着温度的升高而逐渐降低,并且随着拉伸应变率的增大,应力一应变曲线波动程度变大,超细镍纳米线发生断裂时的应变越来越小。在0．01K温度下,超细镍纳米线屈服强度随拉伸应变率的升高迅速降低;但在其它温度条件下,拉伸应变率对弹性模量和屈服强度的影响较小。简要分析尺寸大小对镍纳米线拉伸性能的影响。     

EQ70海洋平台用钢回火后的组织与性能

针对淬火态超高强度EQ70海洋平台用钢进行系列回火试验,研究了回火时间和温度两个参数对其组织和性能的影响。结果表明,马氏体完全分解后继续延长回火时间,试验钢的冲击性能并无明显提高,强度反而下降;提高回火温度可明显缩短马氏体分解时间,提高回火温度以缩短回火时间,可以获得良好的综合力学性能。     

Friction behaviour of diamond-like carbon films with varying mechanical properties

Diamond-like carbon (DLC) films deposited on silicon wafer with varying film thickness were investigated for their micro-scale friction behaviour. Films with three different thicknesses, namely 100 nm, 500 nm and 1000 nm, deposited by a radio frequency plasma-assisted chemical vapor deposition method on Si (100) wafer, were used as the test samples. The elastic modulus of the DLC samples increased with their film thickness. The micro-scale friction tests were conducted in a ball-on-flat type micro-tribotester, using soda lime glass balls with different radii (0.25 mm, 0.5 mm and 1 mm), and with varying applied normal load (load range: 1500 μN to 4800 μN). Results showed that the friction force increased with applied normal load, whereas with respect to the ball size, two different trends were observed. In the case of 100 nm thick sample, friction increased with the ball size at any given normal load, while for 500 nm and 1000 nm thick samples, friction had an inverse relation with the ball size at all applied normal loads. The friction behaviour in the case of the 100 nm thick film was adhesive in nature, whereas for the thicker films plowing was dominant. The friction behaviour of the test samples with the ball size, which was distinctly different, was discussed in terms of the contact area, influenced by their mechanical property, namely, the elastic modulus.     

Classical molecular dynamics simulation of UO2 to predict thermophysical properties

Interatomic potential parameters of UO₂, for a partially ionic potential model, were found out by a fitting method using isothermal compressibility data up to 1600 K. The inter-atomic potential used here is essentially a combined potential model comprising of Bushing–Ida and Morse-type potential to simulate UO₂ system using classical molecular dynamics. It has been shown that the deviation in the estimated lattice parameter from the experimental data as reported in literature is due to the inadequacy of the potential parameter. The calculated deviations in lattice parameter, due to the generation of point defects, with variation of temperature have been discussed. The calculated lattice parameters, thermal expansivity, isothermal compressibility of UO₂, using the current potential parameters are in close agreement with the experimental values. The model also successfully predicts Bredig transition.     

含孔洞的Al2Cu单轴拉伸的分子动力学模拟

建立含孔洞的Al₂Cu分子动力学模拟模型,采用嵌入原子法模拟Al₂Cu模型在常温、恒定工程应变速率的拉伸环境下孔洞大小、数量及孔洞分布对Al₂Cu力学性能的影响。研究结果表明：孔洞的出现使模型内部出现了自由表面并在孔洞内边缘产生了应力集中,从而大大降低材料的抗拉强度以及变形能力;孔洞增大,Al₂Cu的塑性和抗拉强度均明显下降;不同孔洞数量对应的应力应变曲线在弹性变形阶段基本重合,孔洞增多,Al₂Cu的塑性以及抗拉强度都有不同程度的下降;改变孔洞分布,孔洞连线方向与拉伸方向的夹角越小,Al₂Cu表现出越强的塑性和抗拉强度。     

Ultrahigh frequency properties of discontinuous CoFeB/SiO2 multilayer films with high resistivity

A series of multilayers of C036Fe46B18/SiO2 were fabricated by DC/RF magnetron sputtering, and further post-annealed in vacuum magnetic field at 200℃ for 2 h. The results show that the microstructures and electromagnetic properties of C036Fea6BIs/SiO2 multilayer films can be altered by varying the thickness of CoFeB and the process of annealing. High permeability along with high magnetic loss in the GHz frequency range is achieved in the optimized discontinuous multilayer films. Both real and imaginary parts of the complex permeability are larger than 260 at 1.6 GHz for this film, and the resistivity is as high as 1.4 mΩcm. The discontinuous Co36Fea6B18/SiO2 multilayers are supposed to serve as the microwave absorbers and EMI shielding materials in GHz range.     

Mg_7Zn_3合金玻璃转变过程局域结构与动力学关联的分子动力学模拟(英文)

采用分子动力学方法对Mg7Zn3合金快速凝固过程进行计算机模拟,研究玻璃转变过程局域结构与动力学之间的关联。结果表明:以Mg原子为中心的FK多面体和以Zn原子为中心的二十面体局域结构,对Mg7Zn3金属玻璃的形成起关键性作用。Mg(Zn)原子的扩散系数在熔点附近开始偏离Arrhenius关系,而满足幂指数规律。根据均方位移、非相干中间散射函数和非Gauss函数等时间相关函数,发现:随着温度的降低,β驰豫越来越显著,α弛豫时间以VFT指数规律迅速增加;而且半径较小的Zn原子比Mg原子呈现较快的弛豫动力学行为。另外,部分短程有序局域原子结构具有较慢的动力学行为,对β驰豫中笼子效应起主导作用;并随着其数目的大量出现,体系扩散系数开始偏离Arrhenius关系,玻璃形成过程微观结构转变温度T Strg与动力学转变温度Tc非常接近。     

Magnetic properties of CeAg2Ge2

A.c. susceptibility and magnetization measurements of CAg₂Ge₂ are reported. Two phase transitions at T = 7 and 11 K are detected. The magnetization curve at T = 4.2 K has a two-step character.     

Synthesis and measurement of structural and magnetic properties of K-doped LaCoO<Subscript>3</Subscript> perovskite materials

Polycrystalline La_1−x K _x CoO₃ (0 ≤ x ≤ 0.2) rare earth cobaltates have been synthesized by a solution combustion method using glycine as a fuel. The synthesized ceramic materials were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and magnetic measurements and studied for physical properties, such as photocatalytic activity. FTIR measurements in conjunction with XRD showed that phases beyond 10% K doping are accompanied by small amounts of impurities. Chemical titrations show the presence of Co⁴⁺ and account for the Co³⁺-Co⁴⁺ mixed-valency of the system. The parent LaCoO₃ shows spin-glass transition at low temperatures, whereas doped samples show transition from spin-glass behavior to paramagnetic ordering on progressive doping of K. “Mixed-conductor” nature of these ceramics positions them as viable candidates for solid oxide fuel cell (SOFC) applications.