共查询到19条相似文献,搜索用时 406 毫秒
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耐蚀合金Au3 Cu高温冷却过程中能量及结构转变的分子动力学模拟 总被引:1,自引:0,他引:1
张长桥 《化学物理学报(中文版)》2001,14(6)
用分子动力学模拟方法对液态Au3Cu冷却过程进行了研究,考察了不同冷却速度下Au3Cu结构变化特点,原子间相互作用势采用F-S多体势,结构分析采用键取向序和对分析技术.计算结果表明,冷却速度对液态Au3Cu能量及结构转变有重要影响,给出了不同冷却速度下液态Au3Cu结构转变的微观信息. 相似文献
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采用分子动力学模拟方法对液态NiAl凝固过程进行了研究,考察了不同冷却速度下液态NiAl结构变化特点,原子间相互作用势采用F-S多体势,结构分析采用键取向序和对分析技术.计算结果表明,冷却速度对液态NiAl结构转变有重要影响,在不同的冷却速度下, NiAl凝固过程出现了明显不同,冷速为4×1013和4×1012 K/s时, NiAl快速凝固为无序的非晶体结构;而在较慢的8×1011 K/s冷速下, NiAl凝固为晶态结构.给出了不同冷却速度下液态NiAl结构转变的微观信息. 相似文献
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金属Cu熔化结晶过程的分子动力学模拟 总被引:3,自引:0,他引:3
采用常温、常压分子动力学模拟技术,研究了在周期性边界条件下,由864个Cu原子构成的模型系统的熔化、结晶过程。原子间相互作用势采用EAM势。模拟结果表明:在连续升温过程中,金属Cu在1520 K熔化;以不同的冷速进行冷却,在较慢冷却条件下,液态Cu在1010 K结晶;当冷速较快时,液态Cu形成非晶态。分析了升降温过程中熔体偶分布函数、原子体积、能量、MSD随温度的变化特征。 相似文献
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The structure of Y2Rh3Ge has been determined and refined from single-crystal X-ray diffraction data (R = 0.042). It is a rhombohedral, ternary, ordered variant of the cubic Laves structure type MgCu2, with space group
and c = 11.82(1)Å for the triple hexagonal cell. The c/a ratio (2.13) is significantly lower than the value for the triple hexagonal cell of the cubic lattice of the parent structure type (2.45), resulting in shorter distances between Rh and Ge atoms than between Rh atoms. The isotypy of Pr2Rh3Si, Er2Rh3Si, Pr2Rh3Ge, and Er2Rh3Ge has been established from Guinier films. The Y2Rh3Ge structure is compared with the binary compound YRh2, crystallizing with the MgCu2 structure, and with three other simple, ternary, ordered substitution derivatives of the Laves phase types MgZn2 and MgCu2. 相似文献
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Hiroshi Mizoguchi L.N. Zakharov M.A. Subramanian 《Journal of solid state chemistry》2008,181(1):56-60
The new compound Bi2/3Ce1/3Rh2O5 has been discovered. It is currently the only known compound in the Bi-Ce-Rh-O system, and it crystallizes in a previously unknown structure type. The structure was established from single crystal X-ray diffraction data. Interatomic distances indicate the oxidation states as Bi2/33+Ce1/34+Rh23.33+O5. The structure indicates no ordering between Rh3+ and Rh4+. The lack of charge ordering is consistent with the metallic properties determined from electrical conductivity, Seebeck coefficient, and magnetic susceptibility measurements. 相似文献
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Jens Niermann 《Journal of solid state chemistry》2004,177(7):2600-2609
The ternary aluminides R2Rh3Al9 (R=Y, La-Nd, Sm, Gd-Tm, Lu), R2Ir3Al9 (R=Y, La-Nd, Sm, Gd-Lu), and R2Pd3Al9 (R=Y, Gd-Tm) have been prepared by arc melting of the elemental components with an excess of aluminum and dissolving the aluminum-rich matrix in hydrochloric acid. They crystallize with Y2Co3Ga9-type structure: Cmcm, Z=4. The crystal structures of Ho2Rh3Al9 and Er2Ir3Al9 have been refined from single-crystal X-ray data; Ho2Rh3Al9: a=1316.8(3) pm, b=760.2(2) pm, c=933.7(2) pm, R=0.044 for 255 structure factors and 27 variables; Er2Ir3Al9: a=1313.8(2) pm, b=758.5(1) pm, c=933.8(2) pm, R=0.057 (392 F values, 27 variables). The structure may be viewed as consisting of atomic layers of the compositions A=R2Al3 and B=T3Al6 which alternate in the sequence ABAB along the z direction. Approximately 33% and 27% of the A layers were found to be misplaced in the crystals investigated for Ho2Rh3Al9 and Er2Ir3Al9, respectively. The magnetic properties of most iridium-containing compounds have been determined with a superconducting quantum interference device magnetometer. The yttrium and the lanthanum compounds show Pauli paramagnetism, others reflect the magnetic behavior of the rare-earth components. The magnetic ordering temperatures are all lower than 20 K. 相似文献
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The binary compound Rh3Bi14 was synthesized from the elements. The compound is isostructural with Rh3Bi12Br2, crystallizes with the orthorhombic space group Fddd (no. 70) and lattice parameters a=6.8959(15) Å, b=17.379(3) Å, c=31.758(6) Å. The crystal structure consists of a three-dimensional (3D) framework of edge-sharing cubes and square antiprisms (RhBi8/2). It is closely related to the intermetallic compound RhBi4, in which two Y-like frameworks of antiprisms interpenetrate. In Rh3Bi14 and Rh3Bi12Br2, additional bismuth and bromine anions, respectively, fill the channels of the 3D polyhedral framework formed by covalently bonded rhodium and bismuth atoms. High-pressure X-ray powder diffraction data from synchrotron measurements of Rh3Bi14 and Rh3Bi12Br2 indicate a high stability of both compounds in the investigated range from ambient pressure to ca. 30 GPa at ambient temperature. 相似文献
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Mark S. Bailey Helmut Claus John A. Schlueter 《Journal of solid state chemistry》2007,180(4):1333-1339
Li2Rh3B2 has been synthesized at 1000 °C from a stoichiometric mix of rhodium and boron and an excess of lithium. Li2Rh3B2 crystallizes in the orthorhombic space group Pbam (no. 55, Z=2) with room temperature lattice constants a=5.7712(1) Å, b=9.4377(2) Å, c=2.8301(1) Å and cell volume 154.149(6) Å3. The structure was solved from single crystal X-ray diffraction yielding the final R indices (all data) R1=2.8% and wR2=4.7%. The structure is a distortion of the CeCo3B2 structure type, containing a network of Rh6B trigonal prisms and short Li-Li contacts of 2.28(2) Å. Li2Rh3B2 is a diamagnetic metal with a room temperature resistivity of 19 μΩ cm, as determined by magnetic susceptibility and single crystal transport measurements. The measured diamagnetism and electronic structure calculations show that Li2Rh3B2 contains rhodium in a d10 configuration. 相似文献
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在碱性水醇溶液中, 硝酸银与用3-(2-氨乙基氨丙基)三甲氧基硅烷[N-(2-aminoethyl)-3-aminopropyl-trimethoxy- silane, AMPTS]表面修饰后的二氧化硅胶体颗粒相互作用, 发现所生成的氧化银纳米颗粒可以在二氧化硅颗粒表面自组装为氧化银纳米线. 通过调变反应物中Ag/Si摩尔比, 可对氧化银纳米线的形貌进行调控. 在较小的Ag/Si摩尔比下, 可以得到结构均匀、直径约为50 nm、长度几十微米的氧化银纳米线. 随Ag/Si摩尔比增大, 得到的氧化银纳米线逐渐变短变粗, 且结构变得不均匀. 高分辨透射电镜(HRTEM)显示, 所有的氧化银纳米线均由直径10~20 nm的氧化银颗粒定向堆积而得. 利用透射电镜(TEM)对氧化银纳米线的形成过程进行了观察, 并对氧化银颗粒形成及组装机理进行了探讨. 相似文献
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采用一步水热合成法制备了BiPO4、Ag3PO4和BiPO4/Ag3PO4复合光催化剂,通过X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、紫外-可见漫反射(UV-Vis DRS)等表征手段对其组成结构、形貌及光吸收性质进行了表征,结果表明Ag3PO4呈块状结构,BiPO4则分布在其表面,形成的BiPO4/Ag3PO4复合光催化剂具有单斜相和立方晶相结构,带边吸收拓宽至571 nm。以甲基橙和加替沙星为目标污染物,考察了BiPO4/Ag3PO4复合光催化剂在模拟太阳光照射下的降解矿化能力,结果表明复合催化剂比单一催化剂的降解矿化能力更强,稳定性更好。此外,自由基捕获实验表明空穴是该光催化过程中的主要活性物种,·O2-次之。p-n异质结的形成使BiPO4/Ag3PO4复合光催化剂具有较强的电子空穴分离能力是光催化活性提高的主要原因,这与光电流和电化学阻抗谱测试结果相一致。基于以上结果,文中对BiPO4/Ag3PO4光催化降解有机污染物的机理进行了推测。 相似文献
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采用一步水热合成法制备了BiPO_4、Ag_3PO_4和BiPO_4/Ag_3PO_4复合光催化剂,通过X射线粉末衍射(XRD)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)、紫外-可见漫反射(UV-Vis DRS)等表征手段对其组成结构、形貌及光吸收性质进行了表征,结果表明Ag_3PO_4呈块状结构,BiPO_4则分布在其表面,形成的BiPO_4/Ag_3PO_4复合光催化剂具有单斜相和立方晶相结构,带边吸收拓宽至571 nm。以甲基橙和加替沙星为目标污染物,考察了BiPO_4/Ag_3PO_4复合光催化剂在模拟太阳光照射下的降解矿化能力,结果表明复合催化剂比单一催化剂的降解矿化能力更强,稳定性更好。此外,自由基捕获实验表明空穴是该光催化过程中的主要活性物种,·O2-次之。p-n异质结的形成使BiPO_4/Ag_3PO_4复合光催化剂具有较强的电子空穴分离能力是光催化活性提高的主要原因,这与光电流和电化学阻抗谱测试结果相一致。基于以上结果,文中对BiPO_4/Ag_3PO_4光催化降解有机污染物的机理进行了推测。 相似文献
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G.D. Tsyrenova S.F. Solodovnikov E.T. Khobrakova Z.A. Solodovnikova 《Journal of solid state chemistry》2004,177(6):2158-2167
Phase equilibria in the systems Ag2MoO4-MMoO4 (M=Ca, Sr, Ba, Pb, Ni, Co, Mn) and subsolidus phase relations in the systems Ag2MoO4-MO-MoO3 (M=Ca, Pb, Cd, Mn, Co, Ni) were investigated using XRD and thermal analysis. The systems Ag2MoO4-MMoO4 (M=Ca, Sr, Ba, Pb, Ni) belong to the simple eutectic type whereas in the systems Ag2MoO4-MMoO4 (M=Co, Mn) incongruently melting Ag2M2(MoO4)3 (M=Co, Mn) were formed. In the ternary oxide systems studied no other compounds were found. Low-temperature LT-Ag2Mn2(MoO4)3 reversibly converts into the high-temperature form of a similar structure at 450-500°C. The single crystals of Ag2Co2(MoO4)3 and LT-Ag2Mn2(MoO4)3 were grown and their structures determined (space group , Z=2; lattice parameters are a=6.989(1) Å, b=8.738(2) Å, c=10.295(2) Å, α=107.67(2)°, β=105.28(2)°, γ=103.87(2)° and a=7.093(1) Å, b=8.878(2) Å, c=10.415(2) Å, α=106.86(2)°, β=105.84(2)°, γ=103.77(2)°, respectively) and refined to R(F)=0.0313 and 0.0368, respectively. The both compounds are isotypical to Ag2Zn2(MoO4)3 and contain mixed frameworks of MoO4 tetrahedra and pairs of M2+O6 octahedra sharing common edges. The Ag+ ions are disordered and located in the voids forming infinite channels running along the a direction. The peculiarities of the silver disorder in the structures of Ag2M2(MoO4)3 (M=Zn, Mg, Co, Mn) are discussed as well as their relations with analogous sodium-containing compounds of the structural family of Na2Mg5(MoO4)6. The phase transitions in Ag2M2(MoO4)3 (M=Mg, Mn) of distortive or order-disorder type are suggested to have superionic character. 相似文献