基于DFT计算的肟类浮选捕收剂的构效关系（英文）

研究不同取代基的肟类化合物(R¹R²C=NOH,其中R¹/R²为烷基)的结构与其相应浮选性能之间的关系。密度泛函理论(DFT)计算结果表明,在R¹位置引入苯基可以提高捕收剂分子的酸性,而引入庚基可以有效地提高其疏水性,有利于强化范德华相互作用。同时,在R²位置引入的氨基可以提供阳离子位点,并与矿物的负电荷表面相互作用,而引入的羟基可以提供与金属离子形成稳定螯合物的额外作用位点。根据构效关系进行结构优化,筛选得到3种高效捕收剂。这3种捕收剂都具有优异的浮选分离性能,证明本文作者对肟类化合物进行结构改性的有效性。     

硫化矿物表面天然疏水性的密度泛函理论研究(英文)

采用密度泛函理论研究了水在硫化矿物表面的吸附以及硫化矿物的天然可浮性。为了排除氧气和其他因素的影响,所有的计算模型都是在真空环境下建立的。水分子是在黄铁矿与闪锌矿的表面,而不是在水里。对于方铅矿、辉铜矿、辉锑矿和辉钼矿,水分子是在水里,而不是在这些矿的表面。另一方面,黄铁矿表面亲氮气而不亲水,而闪锌矿表面不能吸附水。结果表明,方铅矿、辉锑矿、辉铜矿及辉钼矿是疏水的,而闪锌矿是亲水的。黄铁矿具有一定的亲水性,但是它更倾向于亲气,这是因为黄铁矿与水的作用要比与氮气的作用弱。因此,黄铁矿、方铅矿、辉铜矿、辉锑矿及辉钼矿都具有天然可浮性。     

基于配位理论的碱性硫脲选择性溶金机理

采用电化学方法研究了金及常见伴生金属元素银、铜、镍、铁在高稳定性碱性溶液中阳极溶解的电化学行为,及碱性硫脲浸金的选择性.结果表明:在最佳溶金电势0.42 V时,金在碱性硫脲溶液的溶解电流密度分别是银、铜、镍和铁的3.4,5.2,27.3和42.6倍;而且碱性硫脲体系进行矿物浸出时金的伴生元素浸出率均小于0.1%,浸金具有显著的选择性.采用配合物的化学键理论、配位理论等分析了碱性硫脲选择性溶金的机理.碱性硫脲溶液中金、银、铜、镍和铁分别以Au(TU) 2,Ag(TU) 3,Cu(TU)2 4,Ni(TU)2 4和Fe(TU)2 6的形式存在,Au(TU) 2中反馈σ-π配键的形成显著增强了其稳定性.配合物Ni(TU)2 4和Fe(TU)2 6中,由于硫脲分子的特殊性,各配位体间硫原子和氮原子上电子云互相排斥,使其稳定性有所降低.而且碱性硫脲溶液中,Ag,Cu,Ni,Fe易于形成致密的硫化物钝化膜,在一定程度上也阻碍了金属的进一步溶解.     

Dissolution theory of gold in alkaline thiourea solution(Ⅲ) ——Thermodynamics on dissolution of gold in alkaline thiourea solution containing Na _2SO_3

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硫脲对喷射电铸纳米晶铜组织与性能的影响

采用喷射电铸法制备了不同硫脲浓度下的纳米晶铜铸层,用SEM、XRD方法分析了硫脲对纳米晶铜铸层微观结构和晶粒大小的影响,并对纳米晶铜铸层的力学性能进行了测试.结果表明,硫脲能细化晶粒,致密铸层组织,显著提高铸层的抗拉强度和显微硬度;电铸液中硫脲浓度为10 mg/L时,可获得晶粒尺寸为29 nm的致密铜铸层,其显微硬度和抗拉强度分别为3.1 GPa和645 MPa.电铸液中硫脲浓度从5 mg/L增至10 mg/L时,纳米晶铜铸层的择优取向由(220)晶面转变为(111)晶面.     

First-principles density functional calculations of physical properties of orthorhombic Au2Al crystal

The study attempts to perform a systematical investigation of the thermodynamic, mechanical and electronic properties of orthorhombic Au₂Al crystal by using first-principles calculations incorporated with a quasi-harmonic Debye model. In addition, their temperature, hydrostatic pressure and direction dependences are also addressed. The investigation begins with evaluation of the equilibrated lattice constants and elastic constants of Au₂Al single crystal. Next, the mechanical features of the single crystal, such as ductile-brittle characteristic and elastic anisotropy, are assessed based on the Cauchy pressures, shear anisotropy factors and directional Young's modulus. Alternatively, the pressure-dependence of polycrystalline mechanical properties of Au₂Al, including bulk, shear and Young's moduli, and ductility, brittleness and microhardness characteristics are also estimated. Furthermore, the study also characterizes the temperature-dependence of thermodynamic properties of Au₂Al single crystal, namely, Debye temperature and heat capacity. At last, electronic characteristic analysis is carried out to predict the electronic band structures and density of states profiles of the crystal.The calculation results indicate that Au₂Al crystal is an elastically anisotropic material at zero pressure and a highly ductile material with low stiffness. In addition, the Young's moduli of the crystal would be markedly enhanced with the increase of the hydrostatic pressure. It is also found that the heat capacity of Au₂Al at low temperature strictly sticks to the Debye T³ law.     

杂质对黄铁矿电子性质及反应活性影响的密度泛函理论研究(英文)

采用密度泛函理论计算含有砷、硒、碲、钴或镍等杂质的黄铁矿的结构和电子性质,并采用前线轨道理论讨论含杂质黄铁矿与氧气和黄药的反应活性。杂质的存在使黄铁矿晶胞体积膨胀。钴和镍主要对费米能级附近的能带产生影响,而砷杂质主要对黄铁矿浅部和深部价带产生影响,硒和碲主要影响深部价带。电荷密度分析结果表明,所有的杂质原子都与其周围的原子形成较强的共价相互作用。前线轨道计算表明,砷、钴和镍杂质对黄铁矿的 HOMO 和 LUMO 的影响比硒和碲杂质大。此外,含砷、钴或镍的黄铁矿比含硒或碲的黄铁矿更容易被氧气氧化,而含钴或镍的黄铁矿与黄药捕收剂的作用更强。计算结果与观察到的黄铁矿实际情况相符。     

Density functional theory study on hydrogenation mechanism in catalyst-activated Mg（0001） surface

A small amount of Fe3O4 catalyst is known to substantially improve the adsorption and desorption thermodynamics and kinetics of Mg-based materials. Using density functional theory in combination with nudged elastic band method, the dissociative chemisorptions of hydrogen on both pure and Fe-doped Mg(0001) surfaces were studied. The adsorption energy calculations show that a weakly physisorbed state above pure and Fe-doped Mg surface atoms can serve as a precursor state to dissociative chemisorption. Then, the dissociation pathway of H2 and the relative barrier were investigated. The calculated dissociation barrier (1.08 eV) of hydrogen molecule on a pure Mg(0001) surface is in good agreement with comparable experimental and theoretical studies. For the Fe-doped Mg(0001) surface, the activated barrier decreases to 0.101 eV due to the strong interaction between the s orbital of H and the d orbital of Fe.     

LaNi4.5Al0.5储氢合金固溶相的密度泛函研究

基于密度泛函理论,采用全势线性缀加平面波方法（FLAPW）,研究LaNi4.5Al0.5储氢合金固溶相α-LaNi4.5Al0.5H0.5和α-LaNi4.5Al0.5H1.0中H原子的占位、态密度和电子密度,分析了H原子的加入对固溶体电子结构和稳定性的影响。结果表明：从能量角度计算得到α-LaNi4.5Al0.5H0.5中H原子最可能占据靠近Al的6m位,α-LaNi4.5Al0.5H1.0中的两个H原子最可能占据6m和4h＊位;随着H原子的增加,晶胞主要沿着c轴方向膨胀;Al和Ni,H之间的相互作用是合金含氢固溶体保持稳定的主要因素;态密度图中低能量区域的态密度越大固溶体越稳定;如果EF处于带隙的底部,则体系较稳定。计算结果与已有的实验结果非常一致。     

Molecular dynamics and density functional theory study on relationship between structure of imidazoline derivatives and inhibition performance

The inhibition performance of two imidazoline derivatives, 3-ethylamino-2-undecyl imidazoline (EUI) and chloride-3-ethylamino-3-(2,3-two hydroxyl) propyl-2-undecyl imidazoline sodium phosphate(CEPIP), for Q235 steel in CO₂ saturated solution at 298 K have been tested by weight loss experiment and electrochemical techniques. The adsorption behavior of the two inhibitors on Fe surface has been studied using molecular dynamics (MD) method and density functional theory. The results indicated that the two imidazoline derivatives could both adsorb on the Fe surface firmly through the imidazoline ring and heteroatoms, the two inhibitors both have excellent corrosion inhibition performance.     

Nonstoichiometry and relative stabilities of Y2Ti2O7 polar surfaces: A density functional theory prediction

Density functional theory calculations were carried out to predict the surface structures and relative stabilities of (1 0 0) and (1 1 0) polar surfaces of a complex metal oxide, Y₂Ti₂O₇. Based on a thermodynamic defect model, surface stabilities were evaluated as a direct function of stoichiometry and environmental factors, i.e. oxygen partial pressure and temperature. Calculations show that, as the oxygen partial pressure increases, the most stable termination of the (1 1 0) changes from Y/Ti-rich to O-rich. For the (1 0 0) surfaces, the most stable termination changes from Y/Ti-rich to stoichiometric, and then to O-rich, with increasing oxygen partial pressure. All variants of the (1 1 0) surfaces were found to be more stable than (1 0 0) surfaces. In particular, non-stoichiometric (1 1 0) surfaces are always more stable than their stoichiometric counterparts.     

黄铁矿(100)表面性质的密度泛函理论计算及其对浮选的影响

采用密度泛函理论(DFT)平面波赝势方法计算理想黄铁矿(100)表面的结构弛豫、原子的Mulliken布居以及电子结构,并解释黄铁矿体相中电荷分布异常的原因.从浮选角度分析表面结构和性质对黄铁矿浮选行为的影响.结果表明:黄铁矿(100)表面弛豫较小,表面Fe-s相互作用相对于体相增强;表面5配位的铁原子具有较高的活性;表而层铁硫原子的能隙降低;表面层的导电性强于体相的,表面的电化学活性增强.     

Electronic structure of perylene on Au studied by ultraviolet photoelectron spectroscopy and density functional theory

The electronic structure of perylene was analyzed by using ultraviolet photoelectron spectroscopy to introduce the energy level alignment of perylene/Au interface. The energy level alignment was studied by the onset of the highest occupied molecular orbital level and the shift of the vacuum level of the perylene layer, which was deposited on Au surface by stages. The measured onset of the highest occupied molecular orbital energy level was 1.0 eV from the Fermi level of Au, and the vacuum level was shifted 0.2 eV toward higher binding energy side with additional perylene layer. Furthermore, the density functional theory calculation was performed to identify the valence band spectrum of perylene film. The good agreement between the experimental and theoretical valence band spectrum allows us to assign each peak of the valence band spectrum, which was obtained from the perylene/Au film. The representative molecular orbital shapes, which composed the valence band of perylene, are presented in this report.     

H, O,P,S和N对金属Ni塑性形变机制影响的第一性原理研究

本文基于密度泛函理论研究了H、O、P、S和N杂质以间隙式固溶于Ni(111)后对其变形能力的影响。发现：S、P在晶粒内部不稳定,不易存在于Ni(111)的间隙位置,而易向界面和表面扩散,H、O和N可在晶内分布,且N在Ni晶内分布的倾向性较大。对于Ni (111)<112>滑移系,P使得Ni层错能增大,而H、N、O、S降低了Ni的层错能,即H、N、O、S固溶于Ni使其沿(111)<112>滑移更为容易。总体来看,当外部环境介质H、N、O侵入到Ni基体时,由于使得体系的层错能降低,除产生的氧化、腐蚀等作用外,还使得该区域抵抗变形的能力下降,增大了蠕变变形的可能性。     

Effect of technological factors on bacterial leaching of low-grade Ni-Cu sulfide ore

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Recent trends in experimental and theoretical investigations of chemisorptions on metal-electrolyte interface. I. In situ spectroscopic studies and the density functional theory calculations

New trends in experimental and theoretical investigations of chemisorption on electrodes are considered on examples of in situ spectroscopic studies and the density functional theory calculations. The partial charge transfer during ionic and molecular adsorption from aqueous solutions on coinage and platinum metals and the thermodynamic uncertainty regarding the direction of the charge transfer are discussed. The text was submitted by the authors in English.     

Effect of process parameters on density of magnesium alloy parts by low-pressure expendable pattern casting

The combination of magnesium alloys with the low-pressure expendable pattern casting （LP-EPC） process would bright future for application of magnesium alloys. The researches are focused on the effect of process parameters on the internal casting quality of magnesium alloy parts. AZ91D magnesium alloy castings were produced for different combinations of the LP-EPC process parameters. Specifically, pouring temperature, vacuum, filling velocity and coupling action of these factors were manipulated to observe their effect on the casting porosity and density distribution. The results indicate that the pouring temperature with LP-EPC process is lower than it in gravity casting. The selected process parameters, such as vacuum, filling velocity and coupled modes of them, must ensure melt metal flowing front profile exhibiting smooth and convex shape. The optimal process parameters for the castings are pouring temperature 983-1 023 K, vacuum 0.02-0.03 MPa, filling velocity 60-95 mm/s, and simultaneous filling with sucking.     

Energetics of charged point defects in rutile TiO2 by density functional theory

The defect formation energies of all possible charge states of point defects in TiO₂, including titanium interstitials, titanium vacancies and oxygen vacancies, are calculated in the phase space of temperature, oxygen partial pressure and Fermi level by combining density functional theory (DFT) and thermodynamic calculations. The point defect phase diagram illustrates that fully charged defects dominate in most regimes. The calculations not only give reasonable defect formation energies compared with prior experimental measurements, but also predict n-type TiO₂ at high T and low P_O2, and p-type TiO₂ at low T and high P_O2, which agrees well with experimental data. In addition, we evaluate methods for correcting the effects of artificial electrostatic interactions caused by periodic boundary conditions in the DFT calculations, including the electrostatic potential alignment correction (ΔV correction) and the Makov–Payne correction.     

O2 在不同终端Fe31MnC(001)表面吸附与解离的理论研究

采用密度泛函理论中的广义梯度近似方法（GGA）研究了氧分子在 Fe31MnC(001) 表面的三种不同吸附位（顶位,桥位和面心间位）的吸附行为和C对Fe31Mn磁性的影响。通过吸附能结果发现,氧分子倾向于垂直吸附在四配位饱和的空穴位,而氧原子强烈吸附在相邻的四配位空穴中。以Mn为表层原子的表面均发生了氧分子的解离吸附,桥位吸附对应的吸附结构最稳定。C原子增加了基体的磁化强度杂化,抑制近邻Fe和Mn原子之间的反铁磁相互作用。