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91.
Dr. Baiqi Shao Dr. Sikang Wan Chenjing Yang Dr. Jianlei Shen Dr. Yiwen Li Prof. Hongpeng You Prof. Dong Chen Prof. Chunhai Fan Prof. Kai Liu Prof. Hongjie Zhang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(41):18370-18374
The self-assembly of inorganic nanoparticles into well-ordered structures in the absence of solvents is generally hindered by van der Waals forces, leading to random aggregates between them. To address the problem, we functionalized rigid rare-earth (RE) nanoparticles with a layer of flexible polymers by electrostatic complexation. Consequently, an ordered and solvent-free liquid crystal (LC) state of RE nanoparticles was realized. The RE nanomaterials including nanospheres, nanorods, nanodiscs, microprisms, and nanowires all show a typical nematic LC phase with one-dimensional orientational order, while their microstructures strongly depend on the particles’ shape and size. Interestingly, the solvent-free thermotropic LCs possess an extremely wide temperature range from −40 °C to 200 °C. The intrinsic ordering and fluidity endow anisotropic luminescence properties in the system of shearing-aligned RE LCs, offering potential applications in anisotropic optical micro-devices. 相似文献
92.
S. A. Solov’ev E. V. Gubareni Ya. P. Kurilets 《Theoretical and Experimental Chemistry》2008,44(6):368-373
It has been established that oxides of the rare-earth elements with moderate redox potentials (La2O3, CeO2) increased the activity and working stability of Ni-Al2O3/cordierite catalysts in the reactions of deep and partial oxidation of methane. In the presence of the (NiO + La2O3 + Al2O3)/cordierite catalyst the process of carbon dioxide conversion of methane can be intensified by introduction of oxygen into
the reaction gas mixture which decreases the temperature to achieve high conversion to 75–100 °C and has practically no effect
on selectivity with respect to H2.
Translated from Teoreticheskaya i éksperimental'naya Khimiya, Vol. 44, No. 6, pp. 359–364, November–December, 2008. 相似文献
93.
A Mixed‐Ligand Approach for a Gigantic and Hollow Heterometallic Cage {Ni64RE96} for Gas Separation and Magnetic Cooling Applications 下载免费PDF全文
Wei‐Peng Chen Pei‐Qin Liao Youzhu Yu Prof. Dr. Zhiping Zheng Prof. Dr. Xiao‐Ming Chen Prof. Dr. Yan‐Zhen Zheng 《Angewandte Chemie (International ed. in English)》2016,55(32):9375-9379
Nanosized aggregations of metal ions shielded by organic ligands possessing both exquisite structural aesthetics and intriguing properties are fundamentally interesting. Three isostructural gigantic transition‐metal–rare‐earth heterometallic coordination cages are reported, abbreviated as {Ni64RE96} (RE=Gd, Dy, and Y) and obtained by a mixed‐ligand approach, each possessing a cuboidal framework made of 160 metal ions and a nanosized spherical cavity in the center. Along with the structural novelty, these hollow cages show highly selective adsorptions for CO2 over CH4 or N2 at ambient temperatures. Moreover, the gadolinium analogue exhibits large magnetocaloric effect at ultralow temperatures. 相似文献
94.
Varun A. Baheti Sarfaraj Islam Praveen Kumar Raju Ravi Ramesh Narayanan Dong Hongqun 《哲学杂志》2016,96(1):15-30
A strong influence of Ni content on the diffusion-controlled growth of the (Cu,Ni)3Sn and (Cu,Ni)6Sn5 phases by coupling different Cu(Ni) alloys with Sn in the solid state is reported. The continuous increase in the thickness ratio of (Cu,Ni)6Sn5 to (Cu,Ni)3Sn with the Ni content is explained by combined kinetic and thermodynamic arguments as follows: (i) The integrated interdiffusion coefficient does not change for the (Cu,Ni)3Sn phase up to 2.5 at.% Ni and decreases drastically for 5 at.% Ni. On the other hand, there is a continuous increase in the integrated interdiffusion coefficient for (Cu,Ni)6Sn5 as a function of increasing Ni content. (ii) With the increase in Ni content, driving forces for the diffusion of components increase for both components in both phases but at different rates. However, the magnitude of these changes alone is not large enough to explain the high difference in the observed growth rate of the product phases because of Ni addition. (iv) Kirkendall marker experiments indicate that the Cu6Sn5 phase grows by diffusion of both Cu and Sn in the binary case. However, when Ni is added, the growth is by diffusion of Sn only. (v) Also, the observed grain refinement in the Cu6Sn5 phase with the addition of Ni suggests that the grain boundary diffusion of Sn may have an important role in the observed changes in the growth rate. 相似文献
95.
We present the results of an investigation of the cathodoluminescence of the Eu2+ ion in gallium chalcogenides (Ga2S3) and europium thiogallate (EuGa2S4). We show that the intense wide-band radiation of these compounds is due to the 4f-5d transitions of the Eu2+ ions. With increase in the Eu2+ percent composition from 0.1 to 5.0 mol.% the luminescence brightness increases and then decreases.
Translated from Zhurnal Prikladnoi Spektrskopii, Vol. 67, No. 2, pp. 268–270, March–April, 2000. 相似文献
96.
借助电子顺磁共振技术,对Mn3+/Mn4+=2∶1和1∶1的两个典型体系 在居里温度TC以上温区的顺磁行为进行了实验研究.实验表明,存在一特征温度 Tmin,通过该温度将TC以上的磁行为分成两个明显可区分的温区: 在Tmin以上,共振谱由一对称的单线构成,Lande 因子g值与温度无关且接近 自由电子的值(~20023),线宽随温度呈线性变化等;而在Tmin
关键词:
稀土锰氧化物
电子顺磁共振
交换变窄
自旋-自旋相互作用
自旋-晶格相互作用 相似文献
97.
选用手性氮氧自由基与稀土离子反应,成功组装了2例2p-4f异自旋内消旋配合物[Ln (hfac)3((R)-MePP-Ph-NIT)]2,其中Ln=Eu (1)、Dy (2),hfac=六氟乙酰丙酮,(R)-MePP-Ph-NIT=2-(4-((R)-tert-butyl-2-methylpiperazine-1-carboxylate) phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide。在配合物中,氮氧自由基配体连接2个稀土离子形成环形双核结构。配合物1展现出铕离子的特征荧光。在配合物2中,磁弛豫相关的频率依赖的虚部信号说明了其单分子磁体的特性。 相似文献
98.
Nazar Pavlyuk Grygoriy Dmytriv Alina Bondaruk Wojciech Ciesielski Volodymyr Pavlyuk 《Acta Crystallographica. Section C, Structural Chemistry》2024,80(5):159-165
The ternary germanide Mg5.57Ni16Ge7.43 (cubic, space group Fmm, cF116) belongs to the structural family based on the Th6Mn23-type. The Ge1 and Ge2 atoms fully occupy the 4a (mm symmetry) and 24d (m.mm) sites, respectively. The Ni1 and Ni2 atoms both fully occupy two 32f sites (.3m symmetry). The Mg/Ge statistical mixture occupies the 24e site with 4m.m symmetry. The structure of the title compound contains a three-core-shell cluster. At (0,0,0), there is a Ge1 atom which is surrounded by eight Ni atoms at the vertices of a cube and consequently six Mg atoms at the vertices of an octahedron. These surrounded eight Ni and six Mg atoms form a [Ge1Ni8(Mg/Ge)6] rhombic dodecahedron with a coordination number of 14. The [GeNi8(Mg/Ge)6] rhombic dodecahedron is encapsulated within the [Ni24] rhombicuboctahedron, which is again encapsulated within an [Ni32(Mg/Ge)24] pentacontatetrahedron; thus, the three-core-shell cluster [GeNi8(Mg/Ge)6@Ni24@Ni32(Mg/Ge)24] results. The pentacontatetrahedron is a new representative of Pavlyuk's polyhedra group based on pentagonal, tetragonal and trigonal faces. The dominance of the metallic type of bonding between atoms in the Mg5.57Ni16Ge7.43 structure is confirmed by the results of the electronic structure calculations. The hydrogen sorption capacity of this intermetallic at 570 K reaches 0.70 wt% H2. 相似文献
99.
Tae-Soo You Jing-Tai Zhao Rainer Pttgen Walter Schnelle Ulrich Burkhardt Yuri Grin Gordon J. Miller 《Journal of solid state chemistry》2009,182(9):2430-2442
Two isoelectronic series, Eu(Ga1−xTtx)2 (Tt=Si, Ge, 0≤x≤1), have been synthesized and characterized by powder and single-crystal X-ray diffraction, physical property measurements, and electronic structure calculations. In Eu(Ga1−xSix)2, crystal structures vary from the KHg2-type to the AlB2-type, and, finally, the ThSi2-type structure as x increases. The hexagonal AlB2-type structure is identified for compositions 0.18(2)≤x<0.70(2) with Ga and Si atoms statistically distributed in the polyanionic 63 nets. As smaller Si atoms replace Ga atoms while the number of valence electrons increases, the lattice parameters, unit cell volumes, and Ga–Si distances in this phase region decrease significantly. Although aspects of X-ray diffraction results suggest puckering of the 63 nets for the Si-richest example of the AlB2-type Eu(Ga1−xSix)2, the complete experimental evidence remains inconclusive. On the other hand, in Eu(Ga1−xGex)2, six different structural types were observed as x varies. In addition to EuGa2 (KHg2-type; space group Imma) and EuGe2 (own structure type, space group P3¯m1), the ternary phases studied show four different structures: the AlB2-type for Ga-rich compositions; the YPtAs-type structure for EuGaGe; and two new structures, which are intergrowths of the YPtAs-type EuGaGe and EuGe2, for Ge-rich compositions. These two Ge-rich phases include: (1) Eu(Ga0.45(2)Ge0.55(2))2 containing two YPtAs-type motifs of EuGaGe plus one EuGe2 motif; and (2) Eu(Ga0.40(2)Ge0.60(2))2 containing one YPtAs-type motif alternating with a split site at and z=0.4798(2) with ca. 50% site occupancy by Ga and Ge along the c-axis. Magnetic susceptibilities of three Eu(Ga1−xGex)2 compounds display Curie–Weiss behavior above ca. 100 K, and show effective magnetic moments indicative of divalent Eu with a 4f7 electronic configuration, consistent with. X-ray absorption spectra (XAS). Density of states (DOS) and crystal orbital Hamilton population (COHP) analyses, based on first principles electronic structure calculations, rationalize the observed homogeneity ranges of the AlB2-type phases in both systems and the structural variations as a function of Tt content. 相似文献
100.
The structural, elastic, and electronic properties of NiAl alloyed with rare earth elements Pr, Pm, Sm, and Eu are investigated by using density functional theory (DFT). The study suggests that Pr, Pm, Sm, and Eu are all tend to be substituted for Al site. Ni8Al7Pm possesses the largest ductility. Only the hardness and ductility of Ni8Al7Eu are enhanced simultaneously. The covalency strength of Ni-Al bond in Ni8Al7Pm is higher than that in Ni8Al7Eu. The covalency strength of Al-Al bond and that of Ni-Ni bond in Ni8Al7Eu are higher than that in Ni8Al7Pm. Ni-Pm bond and Ni-Eu bond are covalent, and the covalency strength of Ni-Pm bond is greater. Al-Pm bond and Al-Eu bond show great covalency strength and ionicity, respectively. 相似文献