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When a solid is subjected to external pressure, it can undergo either structural transformation or remain stable in its parent
structure. The sequence of structural transformations, when mapped for similar materials, viz., isostructural, isoelectronic and so on, can be used to create a map showing the evolution of structures under pressure for
such materials. Such maps are useful in predicting high pressure phases. The structural transitions and the stability of materials
as a function of pressure are intricately connected to their electronic structure. Many a times it is advantageous to know
the stability of the material under pressure just by calculating its electronic structure. This can be accomplished only if
several homologues materials are studied and the stability criteria arrived at by correlating their electronic structure with
their structural stability under pressure. Further, as a function of pressure, the electronic structure changes can lead to
enhancement in certain desired electronic, physical or mechanical properties. Several examples are known, wherein, pressure
tuning of the band structure leads to improved properties. In this paper, we have discussed the above mentioned areas and
presented a perspective of the above using the results of our own studies on f-electron based intermetallics (f-IMCs). 相似文献
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H. LUMBANTOBINGT.I. HAAKER 《Journal of sound and vibration》2002,257(3):439-456
This paper is concerned with one-degree-of-freedom aeroelastic oscillations of a seesaw- type structure in a steady wind flow. Here it is assumed that strong wind conditions induce nonlinear aeroelastic stiffness forces that are of the same order of magnitude as the structural stiffness forces. As a model equation for the aeroelastic behaviour of the seesaw-type structure, a strongly nonlinear self-excited oscillator is obtained. The bifurcation and the stability of limit cycles for this equation are studied using a special perturbation method. Both the case with linear structural stiffness and the case with nonlinear structural stiffness are studied. For both cases is assumed a general cubic approximation to describe the aerodynamic coefficient. Conditions for the existence, the stability, and the bifurcation of limit cycles are given. 相似文献
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Mengyao Pan Xiao bai Li Chengjia Xiong Xiaoyi Chen Lebin Wang Xi Chen Lei Pan Hongbo Xu Jiupeng Zhao Yao Li 《Particle & Particle Systems Characterization》2020,37(4):1900495
Colloidal photonic crystals (PCs) possess iridescent and metallic structural color, making them an attractive candidate for anticounterfeiting. However, traditional colloidal PC-based anticounterfeiting materials usually have bending-induced color-switching characteristics or poor flexible stability, significantly affecting their color reproducibility and durability. Here, a novel robust colloidal PC film with bending strain–independent structural color and high flexible stability has been developed through the self-assembly of SiO2 particles into the poly(ethylene glycol) diacrylate (PEGDA) matrix. The unique microstructure of the colloidal PC film contains ordered and disordered arrays of SiO2 nanoparticles embedded into the flexible PEGDA matrix, which is crucial to achieving bending strain–independent structural color. In fact, during the bending process, the colorless disordered arrays act as the buffer space, avoiding deformation of the colored ordered arrays and thus maintaining its original structural color. Remarkably, the film retains its structural and optical integrity after 10 000 times bending, supporting its high flexible stability and robustness. In addition, the film shows high transparency so that it can easily achieve an invisible and visible state transition under switch of weak and strong light. The film is potentially useful for applications in anticounterfeiting and encryption. 相似文献
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铁基非晶稀土合金的结构转变和结构弛豫 总被引:1,自引:0,他引:1
通过对铁基非晶稀土合金结构转变和结构弛豫过程特征的研究,讨论了该材料的稳定性;认为稀土成份是影响合金品质和应用前景的关键因素。 相似文献
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A dual approach based on both structural tailoring and piezoelectric strain actuation, aimed at controlling the free vibration and stability of a spinning circular shaft subjected to axial forces is presented. Due to the involvement in these structural systems of gyroscopic forces and, consequently, of the possible occurrence of divergence and flutter instabilities, the dual control methodology shows a high degree of efficiency toward postponement of the occurrence of these instabilities. The structural model of the shaft as considered in this paper is based on an advanced thin-walled beam that includes the effects of transverse shear, anisotropy of constituent materials, rotatory inertias, etc. The displayed results reveal the synergistic implications of the application of this dual technology toward the enhancement of the dynamic response characteristics and expansion of the domain of stability of these systems. 相似文献
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Strategies to curb structural changes of lithium/transition metal oxide cathode materials & the changes' effects on thermal & cycling stability
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Structural transformation behaviors of several typical oxide cathode materials during a heating process are reviewed in detail to provide in-depth understanding of the key factors governing the thermal stability of these materials. We also discuss applying the information about heat induced structural evolution in the study of electrochemically induced structural changes. All these discussions are expected to provide valuable insights for designing oxide cathode materials with significantly improved structural stability for safe, long-life lithium ion batteries, as the safety of lithium-ion batteries is a critical issue; it is widely accepted that the thermal instability of the cathodes is one of the most critical factors in thermal runaway and related safety problems. 相似文献
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The structural stability and theoretical strength of FCC crystal Ag under uniaxial loading have been investigated by combining MAEAM with Wang modified Born stability criteria. The results reveal that, under sufficient compression, there exists a stress-free BCC phase, which is unstable and slips spontaneously to a stress-free mBCT phase by consuming internal energy. The stable region ranges from −2.076 to 4.390 GPa in the theoretical strength or from −7.972% to 8.721% in the strain correspondingly. The calculated structural energy difference between the BCC and FCC phase is in good agreement with the experimental value. 相似文献
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W. Maass 《Annalen der Physik》1970,480(4):403-410
The Boltzmann equation for an “isolated” gas system is assumed to form a “dynamical system” in a compact subset of the space of continuous distribution functions (existence assumption). Then the asymptotic stability in the sense of Lyapunov of the total Maxwell distribution is investigated (“approach to equilibrium”). Further the influence of persistent perturbations on the stability behaviour of Boltzmann's equation is considered (“structural stability”). 相似文献
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运用第一性原理方法研究了L12型铝合金相Al3Sc和Al3Zr的晶体结构、电子结构和弹性.结合能和形成能的计算表明,两种合金具有较强的合金化能力,且Al3Zr较Al3Sc具有更强的结构稳定性.电子结构分析表明,费米能级以下较多的价电子数决定了Al3Zr具有较强的结构稳定性.计算并分析比较了两种合金相的单晶弹性常数(C11,C12和C44)以及多晶弹性模量(体弹性模量B、剪切模量G、杨氏模量Y、泊松比ν和各向异性因子A).通过对比实验和其他理论计算结果,进一步分析和解释了两种合金相的力学性质. 相似文献
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The structural stability and electrical resistivity of nanocrystalline Cr–N and V–N coatings prepared by ion beam-assisted deposition were studied. The results showed that under helium ion irradiation up to doses of 1.0.1017 ion/cm2 the fine-crystalline objects successively increase their resistance without apparent structural changes. The subsequent dose increase leads to gas-vacancy void formation and chromium nitride structure destruction. The presence of the initial closed porosity in vanadium nitride favors its structural stability at investigated maximum damage doses. 相似文献
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Baimova Yu. A. Dmitriev S. V. Savin A. V. Kivshar’ Yu. S. 《Physics of the Solid State》2012,54(4):866-874
The effect of elastic strain on the mechanical and physical properties of graphene has been intensively studied in recent
years. Using the molecular dynamics method, a surface has been built in the three-dimensional space of components of the plane
strain tensor bounds the region of the structural stability of a flat graphene sheet without considering thermal vibrations
and the influence of boundary conditions. The velocities of sound and the densities of phonon states in graphene subjected
to an elastic strain within the region of the structural stability have been calculated. It has been shown that one of the
velocities of sound becomes zero near the stability boundary of a flat graphene sheet. During biaxial tension of graphene,
there is no gap in its phonon spectrum; however, it forms under uniaxial tension along the zigzag or armchair directions and
also under combined tensile and compressive strains. 相似文献
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Abstract Because of the crucial importance of structural fluctuations for function and stability of proteins, there is a strong interest for the relationships between structural fluctuations, the parameters of protein denaturation and the kinetics of H/D-exchange. Structural fluctuations can be described by volume and entropy fluctuations and these quantities are accessible via the isothermal compressibility, the thermal expansion and the isobaric heat capacity. Our aim is to present the principal problem concerning the experimental procedures to answer those questions using lysozyme and α-lactalbumin. Whereas the transition parameters and the kinetics of the H/D-exchange were obtained using FTIR spectroscopy, the adiabatic compressibility was obtained by a combination of ultrasonic velocimetry and densitometry. It could be shown that the stability of the investigated proteins is correlated with reduced volume fluctuations. The expected direct correlation between H/D exchange rates and structural fluctuations could not be seen and it is assumed that the interactions are more complex than from the intuitive point of view. 相似文献
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Weber UK Burlakov VM Perdigão LM Fawcett RH Beton PH Champness NR Jefferson JH Briggs GA Pettifor DG 《Physical review letters》2008,100(15):156101
Surface templating via self-assembly of hydrogen-bonded molecular networks is a rapidly developing bottom-up approach in nanotechnology. Using the melamine-PTCDI molecular system as an example we show theoretically that the network stability in the parameter space of temperature versus molecular coupling anisotropy is highly restricted. Our kinetic Monte Carlo simulations predict a structural stability diagram that contains domains of stability of an open honeycomb network, a compact phase, and a high-temperature disordered phase. The results are in agreement with recent experiments, and reveal a relationship between the molecular size and the network stability, which may be used to predict an upper limit on pore-cavity sizes. 相似文献
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W. Maass 《Annalen der Physik》1972,483(3):205-210
For the linearized BOLTZMANN equation and a class of “modifications” of the linearized BOLTZMANN equation (including the usual BOLTZMANN equation) exponential-asymptotic stability of the total equilibrium is proved with respect to some boundary and existence assumptions which seem to be physically reasonable. Of course, this structural stability is important if BOLTZMANN 's equation has to be considered under the influence of “perturbations” or if it is substituted by model equations. 相似文献
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Preservation of stability in the presence of structural and/or parametric changes is an important issue in the study of dynamical systems. A specific case is the synchronization of chaos in complex networks where synchronization should be preserved in spite of changes in the network parameters and connectivity. In this work, a methodology to establish conditions for preservation of stability in a class of dynamical system is given in terms of Lyapunov methods. The idea is to construct a group of dynamical transformations under which stability is retained along certain manifolds. Some synchronization examples illustrate the results. 相似文献
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针对一种新型柔索传动差动结构稳定平台结构设计问题,开展平台载荷分析和框架结构强度以及稳定性校核研究。根据平台的实际工况和载荷特点,将载荷划分为惯性载荷、质心偏移加速度载荷、摩擦载荷和环境载荷,分类计算并进行载荷综合和功率估算;以回转架结构为例进行结构静动态校核,根据载荷分析结果,对框架结构进行有限元分析,校核结果显示回转架具有良好的静动态特性:平台框架调转及随载体机动过程中的变形在系统允许的范围之内,满足设计要求;框架结构一阶固有频率为156.04 Hz,远高于伺服系统工作带宽,不会引起谐振,具有较高的结构动态稳定性。 相似文献