金铜合金纳米团簇的制备、性质及应用研究进展

金属纳米团簇是一类新兴的纳米材料，它的直径为1～3 nm,通常由几个到几百个金属原子构成，具有精确的原子个数和空间结构。近几年，研究发现对金纳米团簇进行合金化能够使其产生独特的物理化学性质，超小的尺寸和可调的表面性质使金铜合金团簇(Au-Cu NCs)在催化、传感等方面表现出优良的应用前景。主要综述了近年来Au-Cu NCs的研究成果，总结Au-Cu NCs的制备方法和性质，概述其在传感、催化等领域的应用，探讨Au-Cu NCs研究中的问题，并对Au-Cu NCs的发展前景予以展望。     

合金基因、全息网络相图和全息合金定位设计与研发系统

以系统科学哲学为指导,以Au-Cu合金系为实例,介绍了以下内容:合金基因、合金基因全息信息传输的Gibbs能函数以及AuCuI(Cu4Au8AA)化合物无序化的平衡和亚平衡传输方式,Au3Cu、AuCu和AuCu3亚格子系统的平衡全息网络相图(HNP);描述组元—成分—结构—性能—温度之间的关系;预测设计合金信息的蓝图:Au-Cu合金系的平衡和亚平衡HNP图。实现"网络化、信息化和智能化设计与研发先进合金"的路径规程是"基本组元合金系统—合金基因序列—亚格子合金系统的平衡HNP图—合金系的平衡和亚平衡HNP图—合金基因工程—合金系统全息知识与数据库"。实施此路径规程的基地称之为"全息合金定位设计与研发系统(HAPDS)"。     

3,5-Cl_2-PADAT作为络合滴定铜的新指示剂

提出用3,5-Cl_2-PADAT作为络合滴定铜的新指示剂,在盐酸或硝酸溶液中,铜生成络合物而可直接测定。本法适用于Ag-Cu,Au-Cu合金中铜的测定。     

First Principles Study of Stability and Thermal Properties of AuxCuy Compounds

采用密度泛函理论研究了AuxCuy金属间化合物的稳定性,热学和力学性能。通过计算AuxCuy各合金相的形成能和生成焓可知各个合金相是热力学稳定的,且计算出来的晶格常数与实验值吻合得较好。采用准简谐近似法计算了合金相的定容比热,对与化学键强度相关的德拜温度也进行了讨论。体模量,杨氏模量等弹性性质用Hill法进行了计算。通过计算声子谱和声子态密度讨论了2种不同结构AuCu合金相的稳定性。研究结果将为Au-Cu系的进一步开发应用提供理论基础。     

Au_xCu_y金属间化合物的稳定性和热学性能的第一性原理研究（英文）

采用密度泛函理论研究了Au_xCu_y金属间化合物的稳定性,热学和力学性能。通过计算Au_xCu_y各合金相的形成能和生成焓可知各个合金相是热力学稳定的,且计算出来的晶格常数与实验值吻合得较好。采用准简谐近似法计算了合金相的定容比热,对与化学键强度相关的德拜温度也进行了讨论。体模量,杨氏模量等弹性性质用Hill法进行了计算。通过计算声子谱和声子态密度讨论了2种不同结构AuCu合金相的稳定性。研究结果将为Au-Cu系的进一步开发应用提供理论基础。     

Au-Cu合金的团簇成分式北大核心CSCD

运用描述近程有序结构的"团簇加连接原子"方法,建立了Au-Cu合金的稳定局域结构模型,进而解析了具有特殊性能的成分点,其中包括ASTM手册中列出的3种钎料BAu-11(50Au-50Cu)、BAu-1(37.5Au-62.5Cu)和BAu-2(80Au-20Cu)。结果表明,特殊性能成分金铜合金,具有简单的满足团簇式的成分规律,反映着固溶体近程有序本质结构。     

Au-Cu合金的团簇成分式

运用描述近程有序结构的"团簇加连接原子"方法,建立了Au-Cu合金的稳定局域结构模型,进而解析了具有特殊性能的成分点,其中包括ASTM手册中列出的3种钎料BAu-11(50Au-50Cu)、BAu-1(37.5Au-62.5Cu)和BAu-2(80Au-20Cu)。结果表明,特殊性能成分金铜合金,具有简单的满足团簇式的成分规律,反映着固溶体近程有序本质结构。     

含金三元合金系的研究进展(1996～2007年)

评述了1996～2007年国际上对含金三元合金系相图、相变的研究进展.1996年以来,在主要国际专业刊物上发表了30多个三元金合金系相图的部分等温截面或纵截面,采用实验方法研究相图的工作占了绝大部分.在所研究的上述三元金合金系中,Au-Sn基合金系有11个,Au-Ag基合金系有6个,Au-Cu和Au-Sb基合金系各有4个,Au-Mn和Au-Si基合金系各有2个.这些合金系目前涉及到的主要应用领域为:钎焊材料、电触头材料、电子材料、磁性材料、形状记忆合金材料、金属离子源材料和喷丝头材料等.含金三元合金系的研究反映了当前对新型金合金功能材料的需求动向, 对指导促进相关新合金材料的开发有重要意义.     

高温强化铂合金研究进展

高温强化铂合金是一种先进的高温结构贵金属材料,论述了固溶强化、弥散强化和沉淀强化等铂合金强化方法及特点,力学性能和强化机理,介绍了高温强化铂合金的的研究进展和主要应用情况,最后展望了高温强化铂合金的研究方向。     

弥散强化型铂基高温合金

弥散强化Pt合金的成功开发与应用是20世纪铂合金材料发展最重要的成就。评述了以碳化物和氧化物弥散强化Pt和Pt合金的发展和制备技术、弥散强化Pt合金的结构特征以及弥散强化Pt合金的室温和高温性能,讨论了弥散强化Pt合金的强化机制。     

A NEW VIEWPOINT ON MECHANISM OF PREFERENTIAL SPUTTERING OF Au-Cu ALLOYS

本文介绍了新近关于合金择优溅射机制的一个新观点.这个观点认为,在AuCu合金中所观测到的择优溅射现象,主要是离子轰击诱发的Gibbs偏析的结果;只有当轰击离子的能量低至几百电子伏、接近溅射的“准阈能”值对,质量效应才起明显的作用。     

Electronic structure of Au-Cu alloys

By studying the correlativity between energy, volume and electronic structure of characteristic crystals and bound conditions of OA theory, the potential energy function, atomic volume interactive function and electronic structure of Au-Cu alloys have been determined. Then following the general Vegard‘s law in characteristic theory, the electronic structure and properties of disordered continue solid solution and three ordered alloys with the maximum ordering degree are calculated. It is found that the non-bonding electrons and near-free electrons in outer shell will transform to covalent electrons during alloying. By analyzing the variation of electronic structure and cohesion of ordering and disordered alloys, the transformation of order-disorder transition Au-Cu alloy has been studied.     

Au－Cu合金的微观结构和性质

依据建立在统计热力学和金属电子理论基础上的合金综合理论──合金相的特征晶体理论，对Ａｕ－Ｃｕ合金的微观结构和性质进行了研究．确定了特征性质（势能和体积）的相互作用方程，各特征原子的电子结构及演变特点；计算了合金的形成热、混合Ｇｉｂｂｓ自由能和晶格常数随成分的变化．这些性质的理论值和实验值符合很好。     

Stress corrosion cracking of 18 carat gold

Due to the so-called “parting limit” in gold alloys there is a general belief that copper-gold alloys with a gold content above 40-45 a/o (atomic %) are immune to stress corrosion cracking (SCC) in aqueous solutions. In the present work it is reported that, by an adequate choice of the corrosive environment, it is possible to produce intergranular SCC in Au-Cu alloy of 18 carat gold, equivalent to Au 50 a/o, in aqueous solutions.     

Misfit strain energy in the Au-Cu system

Misfit strain energy has been calculated for the AuCu lattice from interatomic distances and the Morse function; the calculations give results of the same order of magnitude as calculations from elasticity theory. It is shown that electronic rearrangements occur during uniaxial tension, greatly reducing the strain energy from that calculated by ordinary methods. The theory of Pauling is applied and the electronic rearrangements derived from this theory reduce the strain energy to small values. This is not true, however, in other lattices. An explanation is advanced as to why Au-Cu alloys form more exothermically than Au-Ag alloys.     

Potential energies of characteristic atoms on basis of experimental heats of formation of AuCu and AuCu3 compounds （ Ⅰ ）

The systematic science of alloys(SSA) is a framework of the total energy and total volume able to be separated. The potential energy sequences of characteristic atoms at the central sites of the basic clusters in the fcc-based lattice Au-Cu system are separated out from smaller experimental heats of formation of L1₀-AuCu and L1₂-AuCu₃ compounds only, by nine potential energy E-functions and through the use of structural unit inversion method. From these potential energy sequences, the potential energies and heats of formation of the disordered Au_1−xCu_x alloys at 0 K are calculated. The potential energies, heats of formation and T_c-temperatures of order-disorder transitions of the L1₀-AuCu, L1₂-Au₃Cu and L1₂-AuCu₃ compounds, as well as the Au₃Cu-, AuCu-and AuCu₃- type ordered alloys with maximal ordering degrees are calculated too. The results show that the 5th E-function may be chosen for developing it into the free energy-, enthalpy-, vibrational energy- and vibrational entropy-functions for describing thermodynamic properties of the compounds, ordered and disordered phases and for establishing the phase diagram of the Au-Cu system in the future.     

Preparation of Flaky Hexagonal Nanoporous Au-Cu and Au Particles via Dealloying

Nanoporous metals have attracted significant attention owing to their excellent physical, chemical, and biological properties. However, preparing ultrafine nanoporous metal particles (1-5 μm) with specific geometries remains challenging. Herein, we report a simple strategy to prepare ultrafine flaky hexagonal nanoporous Au-Cu and Au particles via dealloying. Mg-based alloy ribbons with ultrafine flaky hexagonal Mg-Au(Cu)-Gd particles dispersed in a Mg-Cu(Au)-Gd metallic glassy matrix were prepared. The size and morphology of the precipitated flaky hexagonal Mg-Au(Cu)-Gd particles were controlled by the solidification process of a Mg₆₁Cu₂₁Au₇Gd₁₁ alloy melt. Ultrafine flaky hexagonal nanoporous Au-Cu particles (diagonal diameter 2.58 ± 0.44 μm, ligament size ~ 28 nm), Au_-1 particles (diagonal diameter 2.38 ± 0.35 μm, ligament size ~ 83 nm) and Au_-2 particles (diagonal diameter 2.39 ± 0.44 μm, ligament size ~ 66 nm) were prepared via ultrasonic-assisted dealloying of Mg₆₁Cu₂₁Au₇Gd₁₁ alloy ribbons in 0.25 M HCl/ethanol, 1 M HCl/ethanol and 0.25 M HNO₃/ethanol solutions, respectively. The ultrafine flaky hexagonal nanoporous Au-Cu and Au particles with a large specific surface area have a uniform particle size and shape, implying that they possess adequate powder fluidity and excellent catalytic properties. Moreover, the formation mechanism of the MgAu(Cu)Gd phase in solidified Mg-Cu-Au-Gd alloys was discussed. This study provides a novel approach for synthesizing nanoporous metal particles with a specific geometry.     

Enhanced catalytic performance for selective oxidation of propene with O_2 over bimetallic Au-Cu/SiO_2 catalysts

Au-Cu bimetallic nanoparticles with uniform size,shape,and compositions were synthesized by wet chemistry method,and then the Au-Cu/SiO_2 catalyst supported on SiO_2 was prepared.Meanwhile,their catalytic activity for the selective oxidation of propene to acrolein using O_2 as an oxidant was evaluated.The bimetallic catalyst shows a significantly enhanced catalytic performance comparing with Au and Cu monometallic catalysts.Characterization of the materials and kinetic study was conducted to explore the cooperating mechanism of Au and Cu for improving the catalytic activity of the bimetallic catalyst.Cu component can segregate to the alloy surface and the Au-Cu alloy transferred to Au-CuO core/shell structure after annealing during the preparation process.Based on the Mars-van Krevelen mechanism for the selective oxidation of propene over the prepared catalysts,the coexistence of CuO can promote the adsorption and activation of O_2.Meanwhile,the electrons transfer from Au to Cu in the catalyst can facilitate the adsorptions of both oxygen on CuO sites and propene on Au sites.The combined effects of the above two aspects result in the high catalytic activity of the Au-Cu/SiO_2 catalyst for selective oxidation of propene to acrolein,compared to the Au/SiO_2 and CuO/SiO_2 catalysts.     

PREPARATION OF ULTRAFINE METAL PARTICLES BY COMBINED METHOD γ-RAY RADIATION—HYDROTHERMAL CRYSTALLIZATION

The γ-ray radiation technique combined with hydrothermal crystallization was firstlyused to prepare ultrafine metallic particles of An,Cu and Au-Cu alloy.Particle sizefor Au in average is about 10 nm.The morphologies were observed by TEM.Thenucleation mechanism of metal particles and their stability are discussed.