入射角度对Ar~+与SiC表面相互作用影响的分子动力学模拟

采用分子动力学模拟方法研究了入射角度对Ar+与SiC样品表面相互作用的影响。由模拟结果可知,入射角度对样品原子溅射影响很大。随着入射角度的增大,Si原子和C原子的溅射量先增加后减小。相同入射角度下,Si原子的溅射阈值比C原子的小,Si原子的溅射量大于C原子的溅射量。初始样品在Ar+以不同角度轰击2000次后的形貌各异。产物中主要以Si原子和C原子为主,有少量的Si类和C类产物。入射角度对产物Si原子的角度分布几乎没有影响,而对产物C原子的角度分布有较小的影响。     

分子动力学模拟C+离子与聚变材料钨的相互作用

采用分子动力学方法模拟不同能量的C+离子与聚变材料钨的相互作用.模拟结果表明:当C+离子入射剂量为3.11×1016 cm-2,入射能量为50eV时,样品表面形成一层碳膜;而入射离子能量为150和250eV时,C+离子入射到样品内与钨原子共同形成碳钨混合层,样品表面没有形成碳膜;碳的沉积率随能量的增大先减小后增加,溅射率随能量的增大先增大后减小;轰击后的样品中,碳原子密度、C-W键密度及C-C键密度分布都随能量的增加逐渐向样品内移动,且C-W键分布厚度随能量的增加而逐渐增加,C-C键分布厚度几乎不随能量变化;在作用过程中极少量的钨原子发生溅射,但引起钨品格损伤严重;碳在轰击后的样品中主要以Csp3杂化形式存在.     

低能Ar+离子束辅助沉积择优取向Pt(111)膜

采用低能Ar+离子束辅助沉积方法,在Mo/Si(100)基底上沉积Pt膜,离子/原子到达比分别为0.1、0.2、0.3.若Ar+离子的入射角为0°,XRD谱分析表明,沉积的Pt膜均呈(111)和(200)混合晶向;当Ar+离子的入射角为45°,沉积的Pt膜均呈很强的(111)择优取向.因此若合理控制Ar+离子束的入射角,可在Mo/Si(100)衬底上制备出具有显著择优取向的Pt(111)薄膜.本文采用Monte Carlo方法模拟低能Ar+离子注入 Pt单晶所引起的原子级联碰撞过程,得出Ar+离子入射单晶铂(200)晶面时,Ar+离子的溅射率与入射角的关系,对Pt膜择优取向的机理作了初步的探讨和分析.     

分子动力学模拟不同入射角度的SiF3+对SiC表面的作用

采用分子动力学模拟方法研究了300K入射能量150eV时,以不同角度(5°、30°、60°和75°)入射的SiF3+与SiC表面的相互作用过程。模拟中使用了用于Si-F-C体系的Tersoff-Brenner势能函数。模拟结果显示,入射SiF3+与SiC表面相互作用后会分解,分解率随着入射角度的增加而减小。分解产物除少量散射外,大部分会沉积在SiC表面,Si和F在SiC表面的平均饱和沉积量随入射角度的增加而减少。随着SiF3+不断轰击SiC表面,SiC表面会形成Si-F-C反应层,且反应层厚度随着入射角度的增加而减少。同时发现SiC中的Si原子较C原子更容易被刻蚀,与实验结果一致。当刻蚀达到稳定,入射角度为5°、30°、60°和75°时,C的刻蚀率分别约为0.026、0.038、0.018、0.005,Si的刻蚀率分别约为0.043、0.051、0.043和0.023。各入射角度下,产物分子种类主要为F、SiF和SiF2。F和SiF产物量随入射角度增加而增加,而SiF2产量随入射角度增加而减少。在入射角度等于5°和30°时,SixFyCz是主要的含C产物;而在入射角度等于60°和75°时,CF是主要的含C产物。在入射角度等于5°和30°时,SiF2是主要的含Si产物;在入射角度等于60°和75°时,SiF是主要的含Si产物。刻蚀主要通过化学增强的物理溅射进行。     

溅射与沉积过程的计算机模拟

应用TRIM和TRIDYN程序模拟氮化硼材料的溅射率与Ar 入射角的关系，Ar 辅助沉积氮化础薄膜与硅基片的界面结构，铜基片溅射率与入射能量的关系，以及Ar 以垂直于表面方向轰击非晶硅产生的溅射速率。铜基片溅射率的计算结果与已有的实验数据相比较表明，两者吻合得很好。硅片的溅射速率与应用38－cm宽束离子源设备的实验结果之间也吻合比较好。     

空心内磁极圆柱形阳极层霍尔推进器溅射仿真北大核心CSCD

溅射对圆柱形阳极层霍尔推进器的稳定运行和寿命具有不可忽视的影响。为了研究D-80空心内磁极圆柱形阳极层霍尔推进器的磁极溅射程度,建立了D-80圆柱形阳极层霍尔推进器的三维全粒子PIC/MCC模型,利用VORPAL仿真软件对D-80圆柱形阳极层霍尔推进器放电-溅射过程进行了仿真,得到了离子轰击到内、外磁极上的入射能量,入射角度的概率分布,分析了溅射粒子在不同放电功率、磁场和气压下的变化规律。仿真结果表明:离子溅射全部发生在内、外磁极的表面上,轰击内磁极的离子能量平均值和入射角都小于轰击外磁极的离子入射能量和入射角,但内磁极的内、外径表面上溅射程度最严重,与实验中磁极溅射形貌一致;高放电电压和高气压下,溅射程度更严重,并且与实验结果一致。     

空心内磁极圆柱形阳极层霍尔推进器溅射仿真

溅射对圆柱形阳极层霍尔推进器的稳定运行和寿命具有不可忽视的影响。为了研究D-80空心内磁极圆柱形阳极层霍尔推进器的磁极溅射程度,建立了D-80圆柱形阳极层霍尔推进器的三维全粒子PIC/MCC模型,利用VORPAL仿真软件对D-80圆柱形阳极层霍尔推进器放电-溅射过程进行了仿真,得到了离子轰击到内、外磁极上的入射能量,入射角度的概率分布,分析了溅射粒子在不同放电功率、磁场和气压下的变化规律。仿真结果表明:离子溅射全部发生在内、外磁极的表面上,轰击内磁极的离子能量平均值和入射角都小于轰击外磁极的离子入射能量和入射角,但内磁极的内、外径表面上溅射程度最严重,与实验中磁极溅射形貌一致;高放电电压和高气压下,溅射程度更严重,并且与实验结果一致。     

溅射与沉积过程的计算机模拟

应用ＴＲＩＭ和ＴＲＥＩＤＹＮ程序模拟氮化硼材料的溅射率与Ａｒ＾＋入射角的关系，Ａｒ＾＋辅助沉积氮化硼薄膜与硅基片的界面结构，铜基片溅射率与入射能量的关系，以及Ａｒ＾＋以垂直于表面方向轰击非晶硅产生的溅射速率。铜基片溅射率的计算结果与已有的实验数据比较表明，两者吻合得很好。     

Ar和Xe在Al(Cr)薄层中的扩散和释放

采用2MeV ~4He~+离子的卢瑟福(Rutherford)背散射技术详细地研究了Ar和Xe在Al(Cr)薄层中的扩散和释放行为。Al(Cr)层中的Ar和Xe是由离子注入引入的,注入的能量为30KeV,Ar的注入剂量为4.3×10~16at./cm~2;Xe的注入剂量为5.2×10~15at·/cm~2恒时退火累积分数释放额的测量表明,Ar和Xe在Al(Cr)层中有着十分不同的释放行为,Ar的迁移和释放较快,而Xe没有观察到明显的释放。气体原子尺寸的不同使得它们与晶格缺陷有着十分不同的束缚能。     

第十九讲 真空溅射镀膜

<正>(接2015年第3期第80页)电子e在电场E作用下被加速,在飞向基体的过程中与Ar气原子发生碰撞,若电子具有足够的能量(约30 e V),则电离出Ar+和一个e,电子飞向基片,Ar+在电场E作用下加速飞向阴极靶并以高能量轰击靶表面,使靶材产生溅射。在溅射粒子中,中性的靶原子(或分子)沉积在基片上形成薄膜。同时被溅射出的二次电子在阴极暗区被加速,在飞向基片的过程中,落入正交电磁     

State of uranophosphates MIPUO6·nH2O (MI = H+, Li+, Na+, K+, Rb+, Cs+, NH 4 + ) in saturated aqueous solutions

The state of uranophosphates M^IPUO₆·nH₂O (M^I = H⁺, Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, NH₄⁺) in aqueous solutions at 25°C was studied. The composition and structure of bottom phases vary depending on the acidity of the equilibrium solutions, which leads to the formation of compounds of different compositions and structures. A physicochemical model of the heterogeneous system M^IPUO₆·nH₂O-aqueous solution was suggested, allowing calculations of the phase diagrams of the bottom phases and equilibrium solutions over them, and also calculations of the equilibrium constants of the heterogeneous reactions occurring in the process.     

Solubility of uranoarsenates MAsUO6·nH2O in water and aqueous HClO4 (M = H+, Li+, Na+, K+, Rb+, Cs+, NH 4 + )

The solubility of poorly soluble uranoarsenates MAsUO₆·H₂O in water and aqueous HClO₄ was determined. The solubility products and Gibbs energies of formation of these compounds were evaluated from the experimental data using the principles of equilibrium thermodynamics. The state of uranoarsenates in aqueous solutions in the range not studied experimentally was estimated.     

Diffusion mechanism of Co2+, Cu2+, Cd2+, Cs+, and Pb2+ ions in the particles of polyaniline silicotitanate

ABSTRACT

The kinetic behavior of Co²⁺, Cu²⁺, Cd²⁺, Cs⁺, and Pb²⁺ in the H-form of polyaniline silicotitanate composite as cation exchanger was studied as a function of particle size, concentration of the exchanging ions, reaction temperature, and drying temperature. The exchange rate was controlled by particle diffusion mechanism as a limited batch technique and is confirmed from the straight lines of B versus 1/r² plots. The values of diffusion coefficients, activation energy, and entropy of activation were calculated and their significance was discussed. The data obtained have been compared with that reported for other organic and inorganic exchangers.     

Ion-exchange of Pb2+, Cu2+, Zn2+, Cd2+, and Ni2+ ions from aqueous solution by Lewatit CNP 80

Removal of trace amounts of heavy metals can be achieved by means of selective ion-exchange processes. The newly developed resins offered a high resin capacity and faster sorption kinetics for the metal ions such as Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+) ions. In the present study, the removal of Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+) ions from aqueous solutions was investigated. Experimental investigations were undertaken using the ion-exchange resin Lewatit CNP 80 (weakly acidic) and were compared with Lewatit TP 207 (weakly acidic and chelating). The optimum pH range for the ion-exchange of the above mentioned metal ions on Lewatit CNP 80 and Lewatit TP 207 were 7.0-9.0 and 4.5-5.5, respectively. The influence of pH, contact time, metal concentration and amount of ion-exchanger on the removal process was investigated. For investigations of the exchange equilibrium, different amounts of resin were contacted with a fixed volume of Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+) ion containing solution. The obtained sorption affinity sequence in the presented work was Ni(2+)>Cu(2+)>Cd(2+)>Zn(2+)>Pb(2+). The metal ion concentrations were measured by AAS methods. The distribution coefficient values for metal ions of 10(-3)M initial concentration at 0.1mol/L ionic strength show that the Lewatit CNP 80 was more selective for Ni(2+), Cu(2+) than it was for Cd(2+), Zn(2+) and Pb(2+). Langmuir isotherm was applicable to the ion-exchange process and its contents were calculated. The uptake of metal ions by the ion-exchange resins was reversible and thus has good potential for the removal of Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+) from aqueous solutions. The amount of sorbed metal ion per gram dry were calculated as 4.1, 4.6, 4.7, 4.8, and 4.7mequiv./g dry resin for Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+), respectively. Selectivity increased in the series: Cd(2+)>Pb(2+)>Cu(2+)>Ni(2+)>Zn(2+). The results obtained showed that Lewatit CNP 80 weakly acidic resin had shown better performance than Lewatit TP 207 resin for the removal of metals. The change of the ionic strength of the solution exerts a slight influence on the removal of Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+). The presence of low ionic strength or low concentration of NaNO(3) does not have a significant effect on the ion-exchange of these metals by the resins. We conclude that Lewatit CNP 80 can be used for the efficient removal of Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+) from aqueous solutions.     

VUV–UV luminescence of Ce3+, Tb3+, Eu3+, and Dy3+ doped GdOCl

The vacuum ultraviolet spectroscopic properties of GdOCl:Re³⁺ (Re³⁺ = Ce³⁺, Tb³⁺, Eu³⁺, and Dy³⁺) are investigated in detail for the first time. The host absorption band is determined to be around 179 nm, and the f–d transition bands as well as the charge transfer bands are assigned. Upon 179 nm excitation, Re³⁺ (Re³⁺ = Ce³⁺, Tb³⁺, Eu³⁺, Dy³⁺) ions shown their characteristic emissions. Energy transfers from Gd³⁺ to Re³⁺ ion were observed. A broad band ranging from 350 to 400 nm corresponding to the d–f transition of Ce³⁺ is observed. Eu³⁺ has typical red emission with the strongest peak at 620 nm; Tb³⁺ shows characteristic transition of ⁵D_3,4 → ⁷F_j, and its spin-forbidden and spin-allowed f–d transitions in VUV region are calculated with Dorenbos’ equations, these calculated values agree well with the experimental results. Dy³⁺ presents yellow emission (⁴F_9/2 → ⁶H_13/2) with the strongest peak at 573 nm.     

Competitive sorption and transport of Pb2+, Ni2+, Mn2+, and Zn2+ in lateritic soil columns

Knowledge of sorption and transport of heavy metals in soils in the presence of other metals is crucial for assessing the environmental risk of these metals. Competitive sorption and transport of four metals, Pb(2+), Ni(2+), Zn(2+), and Mn(2+), were investigated using multi-metal column experiments with lateritic soils obtained from a gold mine impacted by acid mine drainage. Based on Pb(2+) breakthrough time for single-metal system at a pH of approximately 5, the sorption capacity of Pb(2+) was estimated to be higher in lateritic soil than the other metals. For multi-metal systems, the estimated retardation factors for the metals from highest to lowest were: Pb(2+)>Zn(2+)～ Ni(2+)>Mn(2+), suggesting the mobility of metals through lateritic soil for a multi-metal system would be in the order of Mn(2+)>Ni(2+)～ Zn(2+)>Pb(2+). For binary and multi-metal systems, the estimated sorption capacities of individual metals were found to be lower than the sorption capacities in single metal system - indicating possible competition for sorption sites. Mass recoveries estimates showed that the sorption of metals was more reversible under competitive multi-metal systems than in single metal systems.     

Isosteric heats of n-hexane sorption in ion-exchanged NaX containing Co2+, Ni2+, Zn2+, and Cd2+

Sorption—desorption isotherms of n-hexane have been measured at 288 and 298 K in zeolites M_xNa_87-2xX (M = Co, Ni, Zn, Cd) and the corresponding isosteric heats have been obtained. The effect of cations on isosteric heats is highly pronounced at low cowerage, being different for each particular cation. An attempt is made to explain the large differences in those heats in terms of cationic size, charge, electronic configuration, and location in the lattice.     

腐植酸树脂对电镀废水中重金属离子的吸附

利用泥炭为原料制备出腐植酸树脂。在动态条件下 ,研究了腐植酸树脂对重金属离子Pb2 +、Cu2 +、Zn2 +、Ni2 +、Cr3+的吸附效果及条件。同时探讨了腐植酸树脂对Pb2 +、Cu2 +、Zn2 +、Ni2 +、Cr3+的吸附与解吸再生机理。含Pb2 +、Cu2 +、Zn2 +、Ni2 +、Cr3+的电镀废水经腐植酸树脂吸附后 ,废水中重金属离子的含量低于国家排放标准     

Synthesis and luminescence properties of BaTiO3:RE (RE = Gd3+, Dy3+, Tb3+, Lu3+) phosphors

Gd³⁺, Dy³⁺, Tb³⁺ and Lu³⁺ doped BaTiO₃-based phosphors were synthesized with modified solid-state technique at 1000 °C. The optimization of reaction conditions were carried out by thermogravimetry and differential thermal analysis methods (DTA/TG). The reaction products obtained in an air atmosphere were characterized by X-ray powder diffraction (XRD). Surface and elemental analyses were performed by using an SEM instrument. The excitation and emission spectra were recorded by photoluminescence spectrophotometer (PL). The thermoluminescence (TL) properties of BaTiO₃ samples doped with Gd³⁺, Dy³⁺, Tb³⁺ and Lu³⁺ were investigated.     

The study of various parameters affecting the ion exchange of Cu2+, Zn2+, Ni2+, Cd2+, and Pb2+ from aqueous solution on Dowex 50W synthetic resin

A gel resin containing sulfonate groups (Dowex 50W) was investigated for its sorption properties towards copper, zinc, nickel, cadmium and lead metal ions. The use of selective ion exchange to recover metals from aqueous solution has been studied. The ion exchange behavior of five metals on Dowex 50W, depending on pH, temperature, and contact time and adsorbate amount was studied. Experimental measurements have been made on the batch sorption of toxic metals from aqueous solutions using cation exchanger Dowex 50W. The maximum recoveries (about 97%) Cu(2+), Zn(2+), Ni(2+), Cd(2+) and (about 80%) Pb(2+) were found at pH ranges 8-9. The amount of sorbed metal ion was calculated as 4.1, 4.6, 4.7, 4.8, and 4.7mequiv./gram dry resin for Pb(2+), Cu(2+), Zn(2+), Cd(2+), and Ni(2+), respectively. The precision of the method was examined at under optimum conditions. Selectivity increased in the series: Pb>Cd>Cu>Zn>Ni. It has been observed that, selectivity of the -SO(3)H group of the resin increases with atomic number, valance, degree of ionization of the exchanged metals. The equilibrium ion exchange capacity of resin for metal ions was measured and explored by using Freundlich and Langmuir isotherms. Langmuir type sorption isotherm was suitable for equilibrium studies.