Many liquid simple metals (Ga and Sn are prominent examples) have static structure factors $S(k)$ that appear to depart appreciably from the predictions of standard central-force models of liquid structure. The inferred structural anomalies take the form of weak subsidiary maxima on $S(k)$ near the principal diffraction peak, or even asymmetries in the peak itself. They are shown here to be a consequence of corresponding structure introduced into the effective ion-ion interaction by the inclusion of dynamically screened fluctuating dipole interactions between ion cores. The effects are therefore most pronounced in ions that are highly polarizable and in extreme cases actually manifest themselves as nonmonotonic contributions to the pair potential at relatively short range. Less extreme behavior can result merely in a softening of the standard pseudopotential-based pair interaction calculated in the absence of such terms. A calculation of the effective ion-ion potential therefore requires a knowledge of the frequency-dependent ionic and electron gas polarizabilities and the one-electron pseudopotential. Model potentials based on reasonable estimates of all of these are used in conjunction with simulation (Monte Carlo) methods to show that the structural anomalies can indeed be attributed to core-polarization effects.

a Study of the Structural Properties of Metallic Systems: I. Metallic Hydrogen. I. Core-Polarization and the Structure of Simple Metals.

: The present work deals almost exclusively with critically evaluated Knight shift data. Quadrupole effects and relaxation time data, and NMR in ferromagnetic materials are considered with less completeness. The Knight shift, which is measured almost exclusively by the NMR technique, has far-reaching applications in solid state physics, physical metallurgy, and other areas. For instance, it is very sensitive to details of a metal's Fermi surface, and to changes in the Fermi surface caused by alloying, and thus can serve as a sensitive test of models proposed to explain the electronic structure of metals. It is also an important analytical chemical or metallurgical tool in both basic and applied studies. For example, the NMR of metals such as cesium is used for precise measurement of magnetic fields and applications of NMR to phase diagram determinations. NMR theory is reviewed in Chapters 1 through 4, data reduction techniques are discussed in Chapters 5 and 6, and metallurgical applications of NMR are described in Chapter 7. Critical evaluation methods and coverage are detailed in Chapter 8, and the evaluated Knight shifts, together with many other physical properties that have been evaluated to a lesser extent, are treated in Chapter 9. There are summarizing tables both in Chapter 9 and in the review chapters as pertinent to the text. For example, nuclear spin-lattice relaxation times and Korringa ratios for solid nontransition metals are given in Table 2.4, and pressure dependence parameters of the Knight shift for elemental metals in Table 4.1.

Metallic Shifts in NMR. A Review of the Theory and Comprehensive Critical Data Compilation of Metallic Materials. Part I. Review Chapters NMR Tables, Evaluated Knight Shifts in Metals Together with other Solid State and Nuclear Properties,

The three-dimensional charge density wave (CDW) compound ${\mathrm{CuV}}_{2}{\mathrm{S}}_{4}$ is known to undergo phase transitions at $\ensuremath{\sim}91$ and $\ensuremath{\sim}50\phantom{\rule{4pt}{0ex}}\mathrm{K}$. Employing single-crystal x-ray diffraction on an annealed crystal, we confirm the formation of an incommensurate CDW at ${T}_{\text{CDW}}\ensuremath{\approx}91\phantom{\rule{4pt}{0ex}}\mathrm{K}$, and we establish the nature of the transition at ${T}_{\text{lock-in}}\ensuremath{\approx}50\phantom{\rule{4pt}{0ex}}\mathrm{K}$ as a lock-in transition toward a threefold superstructure. As-grown crystals develop the same incommensurate CDW as the annealed crystal does, but they fail to go through the lock-in transition. Instead, the length of the modulation wave vector continues to decrease down to low temperatures in as-grown crystals. These findings are corroborated by distinct temperature dependencies of the electrical resistivity, magnetic susceptibility, and specific heat measured on as-grown and annealed crystals. A superspace model for the crystal structure of the incommensurate CDW suggests that the formation of extended vanadium clusters is at the origin of the CDW. In the lock-in phase, short and long V-V distances persist, but clusters now percolate the entire crystal. The lowering toward orthorhombic symmetry appears to be responsible for the precise pattern of short and long V-V distances. However, the orthorhombic lattice distortion is nearly zero for the annealed crystal, while it is visible for the as-grown material, again suggesting the role of lattice defects in the latter.

/pdf/charge-density-wave-and-lock-in-transitions-of-cuv-2-s-4-2uc1q8my1o.pdf

Charge density wave and lock-in transitions of CuV 2 S 4

The quasiskutterudite superconductors ${A}_{3}{T}_{4}{\mathrm{Sn}}_{13}$ ($A=\text{Sr}$, Ca; $T=\text{Ir}$, Rh, Co) are highly tunable, featuring a structural quantum critical point. We construct a temperature-lattice constant phase diagram for these isovalent compounds, establishing ${\mathrm{Ca}}_{3}{\mathrm{Rh}}_{4}{\mathrm{Sn}}_{13}$ and ${\mathrm{Ca}}_{3}{\mathrm{Co}}_{4}{\mathrm{Sn}}_{13}$ as members close to and far away from the structural quantum critical point, respectively. Deconvolution of the lattice specific heat and the electrical resistivity provide an approximate phonon density of states $F(\ensuremath{\omega})$ and the electron-phonon transport coupling function ${\ensuremath{\alpha}}_{\text{tr}}^{2}F(\ensuremath{\omega})$ for ${\mathrm{Ca}}_{3}{\mathrm{Rh}}_{4}{\mathrm{Sn}}_{13}$ and ${\mathrm{Ca}}_{3}{\mathrm{Co}}_{4}{\mathrm{Sn}}_{13}$, enabling us to investigate the influence of the structural quantum critical point. Our results support the scenario of phonon softening close to the structural quantum critical point, and explain the enhancement of the coupling strength on approaching structural instability.

Soft phonon modes in the vicinity of the structural quantum critical point

Enhancing the figure of merit in thermoelectric materials by adding silicate aerogel

We report the effects of Ge partial substitution for Si on local atomic and electronic structures of thermoelectric materials in binary compound cobalt monosilicides (). Correlations between local atomic/electronic structure and thermoelectric properties are investigated by means of X-ray absorption spectroscopy. The spectroscopic results indicate that as Ge is partially substituted onto Si sites at , Co in CoSi1?xGex gains a certain amount of charge in its 3d orbitals. Contrarily, upon further replacing Si with Ge at , the Co 3d orbitals start to lose some of their charge. Notably, thermopower is strongly correlated with charge redistribution in the Co 3d orbital, and the observed charge transfer between Ge and Co is responsible for the variation of Co 3d occupancy number. In addition to Seebeck coefficient, which can be modified by tailoring the Co 3d states, local lattice disorder may also be beneficial in enhancing the thermoelectric properties. Extended X-ray absorption fine structure spectrum results further demonstrate that the lattice phonons can be enhanced by Ge doping, which results in the formation of the disordered Co-Co pair. Improvements in the thermoelectric properties are interpreted based on the variation of local atomic and electronic structure induced by lattice distortion through chemical substitution.

Effect of local atomic and electronic structures on thermoelectric properties of chemically substituted CoSi

X-ray scattering (XRS), x-ray absorption near-edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) spectroscopic techniques were used to study the electronic and atomic structures of the high-quality Sr3Ir4Sn13 (SIS) single crystal below and above the transition temperature (T* ≈ 147 K). The evolution of a series of modulated satellite peaks below the transition temperature in the XRS experiment indicated the formation of a possible charge density wave (CDW) in the (110) plane. The EXAFS phase derivative analysis supports the CDW-like formation by revealing different bond distances [Sn1(2)-Sn2] below and above T* in the (110) plane. XANES spectra at the Ir L3-edge and Sn K-edge demonstrated an increase (decrease) in the unoccupied (occupied) density of Ir 5d-derived states and a nearly constant density of Sn 5p-derived states at temperatures T < T* in the (110) plane. These observations clearly suggest that the Ir 5d-derived states are closely related to the anomalous resistivity transition. Accordingly, a close relationship exists between local electronic and atomic structures and the CDW-like phase in the SIS single crystal.

/pdf/electronic-and-atomic-structures-of-the-sr-3-ir-4-sn-13-16v3pmji36.pdf

Electronic and atomic structures of the Sr 3 Ir 4 Sn 13 single crystal: A possible charge density wave material

Handle everyday research tasks with reliable, citation-backed results

Your personal Research Agent to handle research tasks with citation-backed results

Popular Tasks used by Researchers

How can I help with your research?

Meet SciSpace

Get more enhanced response by uploading the PDFs you want me to reference.

No relevant PDFs in your library

SciSpace is the AI research assistant for academics. Run systematic literature reviews on 280M+ papers, and write papers with cited sources. Trusted by 1M+ students, PhDs & researchers.

SciSpace | AI for Research

Analyze PDFs

Code & Manuscripts

Funding & Grants

Literature & Patents

Medical & Clinical Data

Systematic Review

Visualize & Present

Web & Data

Build a Google Scholar-like website for your research.

Build a website

Create charts and images for your research

Create a Chart

Write a paper for submission to a journal

Draft a manuscript

Patent Search

Design eye-catching scientific posters in minutes.

Scientific Poster Generation

Systematic Literature Review

One task is running at the moment. Your messages will be shown right after.

Drag and drop or click here to browse

Loved by <highlight>1 million+</highlight> researchers

Extract a list of specific topics and their sources from unstructured text

Topics

Compare and analyze relevant papers that matches with your search

Papers

Get insights from PDFs and bookmarked papers from your library

My library

Recent searches

Try searching for:

Catch AI-generated content in scholarly and non-scholarly content

{ai} Detector

Ai Writer

Get PDF Summaries, highlighted text explanations 

Chat with PDF

Effortlessly create in-text citations and bibliographies in APA and 2,500 other formats

Citation generator

Get explanations, summaries, and answers on academic papers

Ease up your research workflow with {scispace}'s cohort of exciting AI tools

Elevate your academic writing skills and convey your ideas the way you want

Paraphraser

Explore our range of reading and writing tools

Your file is being prepared and should be ready in a few minutes. If it's a large file, it might take a bit longer. You can close this window, and we'll email you the file when it's done.

You have reached a maximum limit of <strong>{limit}</strong> columns in the table. Remove at least <strong>1</strong> column to add or create another one.

J. L. Chen

Author Tools

Chat about Author

Papers

Effect of local atomic and electronic structures on thermoelectric properties of chemically substituted CoSi

Electronic and atomic structures of the Sr 3 Ir 4 Sn 13 single crystal: A possible charge density wave material