Point Defects and Their Properties in the Fe20Ni20Cr20Co20Cu20 High-Entropy Alloy

JETP Letters - The characteristics of interstitial atoms and vacancies in the Fe20Ni20Cr20Co20Cu20 high-entropy alloy have been determined by the molecular dynamics and statics methods. The effect...     

Elastic Dipoles in Crystal and Glassy Aluminum and High-Entropy Fe20Ni20Cr20Co20Cu20 Alloy

JETP Letters - Molecular dynamics simulation has shown that anisotropic local atomic configurations, which are in essence elastic dipoles, exist in noncrystalline structures of Al and FeNiCrCoCu....     

Photoelectron spectra of Ga20, In20 and Tl20

The HeI photoelectron spectra of Ga₂O, In₂O, and Tl₂O, as well as atomic In, have been obtained. Some spectral features of the recently published photoelectron spectrum of Al₂O differ noticeably from the heavier suboxides. The assignment of spectral features is supported by fully relativistic DVM SSC X_α calculations, which have been extended to include Al₂O. Best agreement is obtained between calculation and experiment for linear Al₂O, but for bent heavier metal suboxides. In general, the spectral features are indicative of ionic bonding, analogous to the behavior of group IIIB monohalides. Along the sequence Al₂O:Ga₂O:In₂O:Tl₂O, the highest occupied orbital becomes less and less localized on the metal atoms, with a rather dramatic decrease in metal character occurring at Tl₂O. The latter effect is attributable to a change in relative energies of the charge-adjusted metal and oxygen atomic orbitais and relativistic effects., A decrease in the relative ionization cross-section for molecular orbitais which have a large metal ns contribution is correlated with a similar behavior of the relative (ns)⁻¹cross-section for the corresponding atoms.     

Magnetic properties and promising cryogenic magneto-caloric performances of Gd20Ho20Tm20Cu20Ni20 amorphous ribbons

The magnetic cooling utilizing magneto-caloric effect is recognized as promising energy efficiency and environmentally friendly technology.Here we report a systematical study on the microstructures,magnetic properties and cryogenic magneto-caloric performances of the Gd₂₀Ho₂₀Tm₂₀Cu₂₀Ni₂₀ amorphous ribbons.It is found that the ribbons reveal a second-order phase transition and are accompanied by a table-shaped magneto-caloric effect.The calculated magneticentropy-change maximum |ΔSM|,temperature averaged entropy change(i.e.,TEC(10)),and refrigerant capacity reach 13.9 J/kg·K,13.84 J/kg-K and 740 J/kg with magnetic field change of 0-7 T,respectively,indicating that the present Gd₂₀Ho₂₀Tm₂₀Cu₂₀Ni₂₀ amorphous ribbons are good candidates for magnetic cooling.     

Structures and stabilities of endo- and exohedral Si20H20 derivatives: X@Si20H20 and XSi20H20, X = H + , H,N, P,C − , and Si −

Geometries, relative energies, and stabilities of endo- and exohedral complexes, X@Si₂₀H₂₀ and XSi₂₀H₂₀, (X = H⁺, H, N, P, C^?, and Si^?) are calculated at B3LYP/6-31G* level. The energy minimum structure of Si₂₀H₂₁ ⁺ shows that the proton cannot be positioned in the Si₂₀H₂₀ centre, but prefers attach to Si₂₀H₂₀ exohedrally with C_2v symmetry. Most investigated I_h endohedral complexes X@Si₂₀H₂₀ (X = H, N, P, C^?, and Si^?) are local minima, except for ²N@Si₂₀H₂₀, which is a high-order saddle point. Inclusions energies of the endohedral complexes are calculated, and it reveals that energy penalties caused by encapsulation are rather small. Exohedral complexes XSi₂₀H₂₀ (X = H, N, P, C^?, and Si^?) have C_2v or C_s local minima, and most of them are more stable than their endohedral isomers with the exception of C_2v ⁴PSi₂₀H₂₀ and ⁴Si^?Si₂₀H₂₀.     

C20 Carbinofullerene Chains

Physics of the Solid State - The results of computer simulation of a new one-dimensional carbon structure representing chains composed of C20 carbinofullerenes are presented. Their binding energies...     

Absorption spectra of cesium halides at 20 K from 12 to 20 eV

The optical absorption down to 20 K of thin films of Cs-halides are reported in the energy range from 12 to 20 eV. The multiple structure in the optical spectra of CsI at low temperature can be explained by the excitons associated with the s-like and d-like conduction band states at the Г point. Spectra of CsBr and CsC1 can be understood by analogy with CsI.     

Na掺杂对C20H20分子的电子输运性质影响

利用第一性原理密度泛函理论和非平衡格林函数方法研究了Na@C₂₀H₂₀分子的电子输运性质. 计算结果显示它的I-V曲线在偏圧 V范围内表现出了较好的线性特性, 出现了明显的负微分电阻现象, 并得到其平衡电导为0.0101G₀. 通过与Li@C₂₀H₂₀分子对比分析, 发现掺杂Na不仅能提高C₂₀H₂₀分子的电子输运能力, 而且 关键词： 20H₂₀分子')" href="#">Na@C₂₀H₂₀分子 电子输运 负微分电阻     

20 kV/20 kHz/100 A高压脉冲源设计

设计了一种基于功率金属氧化物半导体场效应晶体管(MOSFET)为开关的高压脉冲电源。采用自匹配传输线结构线路形式,串联多个以光纤信号隔离触发的MOSFET作为高耐压开关,在传输线的外皮产生2个纳秒脉冲,再用传输线变压器对2个纳秒脉冲进行功率合成,在200 Ω负载上输出了幅度20 kV,重复频率20 kHz,脉冲宽度约40 ns的脉冲。分析脉冲源装置结构,对实验装置建立仿真模型,阐述了输出波形畸变的原因,给出了影响输出脉冲波形特性的因素,为下一步优化波形工作提供了理论参考。     

Origin of the planar Hall effect in nanocrystalline Co60Fe20B20

An angle dependent analysis of the planar Hall effect (PHE) in nanocrystalline single-domain Co(60)Fe(20)B(20) thin films is reported. In a combined experimental and theoretical study we show that the transverse resistivity of the PHE is entirely driven by anisotropic magnetoresistance (AMR). Our results for Co(60)Fe(20)B(20) obtained from first principles theory in conjunction with a Boltzmann transport model take into account the nanocrystallinity and the presence of 20 at.?% boron. The ab initio AMR ratio of 0.12% agrees well with the experimental value of 0.22%. Furthermore, we experimentally demonstrate that the anomalous Hall effect contributes negligibly in the present case.     

Quadrupole transitions in 20Ne

Untruncated shell model calculations in the 1s-0d shell using Chung-Wildenthal effective interactions have been performed for ²⁰Ne and the electron scattering form factors for elastic scattering and for the excitation of 2₁⁺, 2₁⁺ and 2₃⁺ states have been examined. Saxon-Woods wave functions and a phase-shift analysis have been used. It is shown that within the limited space of the 1s-0d shell, it is possible to obtain vastly different momentum transfer dependence for the electro-excitation of ΔJ^π = 2⁺ transitions. The 2₁⁺ and 2₂⁺ states are seen to be adequately described by the wave functions obtained in this calculation, but 2₃⁺ is not described well.     

20th International Spectroscopy Colloquium

Chronicle

20th International Spectroscopy Colloquium