Equilibrium and Kinetic Properties of Minerals

1998 ◽  
Vol 62 (5) ◽  
pp. 581-583
Author(s):  
Simon A. T. Redfern
Keyword(s):  
Solid State ◽  
Statistical Mechanics ◽  
Structural Features ◽  
Atomic Scale ◽  
Kinetic Properties ◽  
Computational Power ◽  
Equilibrium Thermodynamics ◽  
Bulk Properties ◽  
Scale Characteristics ◽  
Number Of Publications

How can the equilibrium and non-equilibrium thermodynamics of minerals be understood from their atomic-scale structural features? How can they be predicted, simply from models for the forces between atoms? Advances in analytical theory, statistical mechanics, experimental solid-state science, computational power, and the sophistication of a mineralogical approach that brings all of these together, means that these questions, once imponderable, are now realistically tractable. These questions have been exercising the minds of mineralogists over the last decade or so, and have motivated many developments in the science. Acting as way-markers along the path, there are a number of publications which have followed from meetings where these questions have been addressed. It is now twelve years since the publication of Microscopic to Macroscopic, an edition of Reviews in Mineralogy (Kieffer and Navrotsky, 1985) that sought to identify the fundamental controls on the bulk properties of minerals in terms of their atomic-scale characteristics.

scholarly journals Porous Characteristics of Three-Dimensional Disordered Graphene Networks

Crystals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 127
Author(s):  
YongChao Wang ◽  
YinBo Zhu ◽  
HengAn Wu
Keyword(s):  
Pore Size ◽  
Low Temperatures ◽  
Gas Adsorption ◽  
Three Dimensional ◽  
Md Simulations ◽  
Structural Features ◽  
Atomic Scale ◽  
Critical Factors ◽  
Chlorination Process ◽  
Porous Morphology

The porous characteristics of disordered carbons are critical factors to their performance on hydrogen storage and electrochemical capacitors. Even though the porous information can be estimated indirectly by gas adsorption experiments, it is still hard to directly characterize the porous morphology considering the complex 3D connectivity. To this end, we construct full-atom disordered graphene networks (DGNs) by mimicking the chlorination process of carbide-derived carbons using annealing-MD simulations, which could model the structure of disordered carbons at the atomic scale. The porous characteristics, including pore volume, pore size distribution (PSD), and specific surface area (SSA), were then computed from the coordinates of carbon atoms. From the evolution of structural features, pores grow dramatically during the formation of polyaromatic fragments and sequent disordered framework. Then structure is further graphitized while the PSD shows little change. For the obtained DGNs, the porosity, pore size, and SSA increase with decreasing density. Furthermore, SSA tends to saturate in the low-density range. The DGNs annealed at low temperatures exhibit larger SSA than high-temperature DGNs because of the abundant free edges.

Cluster, Surface and Bulk Properties of ZnCd Binary Alloys: Molecular-Dynamics Simulations

2005 ◽  
Vol 502 ◽  
pp. 51-56 ◽  
Author(s):  
Sakir Erkoc
Keyword(s):  
Molecular Dynamics ◽  
Molecular Dynamics Simulations ◽  
Density Functional ◽  
Structural Features ◽  
Bulk Materials ◽  
Bulk Properties ◽  
Atom Clusters ◽  
Dynamics Simulations ◽  
Mixed Clusters ◽  
Stable Structures

The structural and electronic properties of isolated neutral ZnmCdn clusters for m+n £ 3 have been investigated by performing density functional theory calculations at B3LYP level. The optimum geometries, vibrational frequencies, electronic structures, and the possible dissosiation channels of the clusters considered have been obtained. An empirical many-body potential energy function (PEF), which comprices two- and three-body atomic interactions, has been developed to investigate the structural features and energetics of ZnmCdn (m+n=3,4) microclusters. The most stable structures were found to be triangular for the three-atom clusters and tetrahedral for the four-atom clusters. On the other hand, the structural features and energetics of Znn-mCdm (n=7,8) microclusters, and Zn50, Cd50, Zn25Cd25, Zn12Cd38, and Zn38Cd12 nanoparticles have been investigated by performing molecular-dynamics computer simulations using the developed PEF. The most stable structures were found to be compact and three-dimensional for all elemental and mixed clusters. An interesting structural feature of the mixed clusters is that Zn and Cd atoms do not mix in mixed clusters, they come together almost without mixing. Surface and bulk properties of Zn, Cd, and ZnCd systems have been investigated too by performing molecular-dynamics simulations using the developed PEF. Surface reconstruction and multilayer relaxation on clean surfaces, adatom on surface, substitutional atom on surface and bulk materials, and vacancy on surface and bulk materials have been studied extensively.

scholarly journals Redox-State Dependent Spectroscopic Properties of Porous Organic Polymers Containing Furan, Thiophene, and Selenophene

2017 ◽  
Vol 70 (11) ◽  
pp. 1227 ◽  
Author(s):  
Carol Hua ◽  
Stone Woo ◽  
Aditya Rawal ◽  
Floriana Tuna ◽  
James M. Hook ◽  
...  
Keyword(s):  
Solid State ◽  
Redox State ◽  
Spectroscopic Properties ◽  
Structural Features ◽  
Organic Polymers ◽  
Stimuli Responsive ◽  
Porous Organic Polymers ◽  
Paramagnetic Resonance ◽  
Responsive Materials ◽  
State Dependent

A series of electroactive triarylamine porous organic polymers (POPs) with furan, thiophene, and selenophene (POP-O, POP-S, and POP-Se) linkers have been synthesised and their electronic and spectroscopic properties investigated as a function of redox state. Solid state NMR provided insight into the structural features of the POPs, while in situ solid state Vis-NIR and electron paramagnetic resonance spectroelectrochemistry showed that the distinct redox states in POP-S could be reversibly accessed. The development of redox-active porous organic polymers with heterocyclic linkers affords their potential application as stimuli responsive materials in gas storage, catalysis, and as electrochromic materials.

How Small Is Too Small ? Understanding The Electronic Structure Of Atomic-Scale Transistors

1999 ◽  
Vol 5 (S2) ◽  
pp. 120-121
Author(s):  
D. A. Muller ◽  
T. Sorsch ◽  
S. Moccio ◽  
F. H. Baumann ◽  
K. Evans-Lutterodt ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Electrical Properties ◽  
Thermal Oxidation ◽  
Electronic Devices ◽  
Local Environment ◽  
Gate Oxide ◽  
Atomic Scale ◽  
Gate Oxides ◽  
Bulk Properties ◽  
Commercial Use

The transistors planned for commercial use ten years from now in many electronic devices will have gate lengths shorter than 130 atoms, gate oxides thinner than 1.2 nm of SiO2 and clock speeds in excess of 10 GHz. It is now technologically possible to produce such transistors with gate oxides only 5 silicon atoms thick[l]. Since at least two of those 5 atoms are not in a local environment similar to either bulk Si or bulk SiO2, the properties of the interface are responsible for a significant fraction of the “bulk” properties of the gate oxide. However the physical (and especially their electrical) properties of the interfacial atoms are very different from .bulk Si or bulk SiO2. Further, roughness on an atomic scale can alter the leakage current by orders of magnitude.In our studies of such devices, we found that thermal oxidation tends to produce Si/SiO2 interfaces with 0.1-0.2 nm rms roughness.

Application of Eddy Currents in Processed Materials Structural Evaluation

2012 ◽  
Vol 730-732 ◽  
pp. 715-720
Author(s):  
Telmo G. Santos ◽  
João Faria ◽  
Pedro Vilaça ◽  
R.M. Miranda
Keyword(s):  
Electrical Conductivity ◽  
Solid State ◽  
Eddy Currents ◽  
Microstructural Analysis ◽  
Structural Features ◽  
Crystal Defects ◽  
Electrical Currents ◽  
Friction Stir ◽  
Characterization Technique ◽  
Physical Phenomena

Eddy currents are based on electromagnetic induction and analysis of electrical currents on conductive materials. This method is used for thickness measurements, corrosion and defects detection, electrical conductivity and magnetic permeability measurements. Recently, it has been exploited as a materials characterization technique, namely in solid state welding, since, compared to hardness, it is based in distinct physical phenomena. Electrical conductivity is controlled by electronic mobility, while hardness depends on crystal defects and thus a scale factor exists. This paper presents results of this characterization technique applied to multipass solid state friction stir processing (FSP) of AA1100 alloy. These results were compared to microstructural analysis and hardness measurements and show that eddy current is a feasibly, reliable and expedite technique to characterize processed materials. The electrical conductivity measured by eddy currents, maps more precisely structural features, while hardness does not. Measurement of electrical conductivity field suggests having potential to constitute an alternative and/or complement to hardness evaluation with the further advantage of being a non-destructive method.

scholarly journals Layer-by-Layer Structural Identification of 2D Ruddlesden-Popper Hybrid Lead Iodide Perovskites by Solid-State NMR Spectroscopy

2020 ◽  
Author(s):  
Jeongjae Lee ◽  
Woocheol Lee ◽  
Keehoon Kang ◽  
Takhee Lee ◽  
Sung Keun Lee
Keyword(s):  
Solid State ◽  
Nmr Spectroscopy ◽  
Solid State Nmr ◽  
Structural Features ◽  
Layer By Layer ◽  
Lead Iodide ◽  
Materials Properties ◽  
Non Invasive ◽  
Local Bonding ◽  
Halide Perovskites

Application of two-dimensional (2D) organic-inorganic hybrid halide perovskites for optoelectronic devices requires detailed understanding of the local structural features including the Pb-I bonding in the 2D layers and the capping ligand-perovskite interaction. In this study, we show that <sup>1</sup>H and <sup>207</sup>Pb solid-state Nuclear Magnetic Resonance (NMR) spectroscopy can serve as a non-invasive and complementary technique to quantify the composition and to probe the local structural features of 2D Ruddlesden-Popper phase BA<sub>2</sub>MA<i><sub>n</sub></i><sub>-1</sub>Pb<i><sub>n</sub></i>I<sub>3<i>n</i>+1</sub> (<i>n</i>=1-4) with butylammonium (BA) spacers. <sup>207</sup>Pb echo and <sup>1</sup>H-detected <sup>207</sup>Pb→<sup>1</sup>H heteronuclear correlation (HETCOR) experiments enables layer-by-layer structural detection of 2D halide perovskites. We show that the observed correlation between <sup>207</sup>Pb NMR shifts and mean Pb-I bond lengths around each Pb site allows us to probe the local bonding environment of Pb via its <sup>207</sup>Pb NMR shift. We envisage that this technique will be vital for better understanding the materials properties as determined by the local atomistic environments in multi-dimensional halide perovskites.

scholarly journals FEI Titan 80-300 TEM

2016 ◽  
Vol 2 ◽  
Author(s):  
Andreas Thust ◽  
Juri Barthel ◽  
Karsten Tillmann
Keyword(s):  
Electron Microscope ◽  
Solid State ◽  
Spherical Aberration ◽  
Atomic Scale ◽  
Atomic Resolution ◽  
Lens System ◽  
Stage Design ◽  
Precise Positioning ◽  
Transmission Electron ◽  
Wide Range

The FEI Titan 80-300 TEM is a high-resolution transmission electron microscope equipped with a field emission gun and a corrector for the spherical aberration (<em>C</em><sub>S</sub>) of the imaging lens system. The instrument is designed for the investigation of a wide range of solid state phenomena taking place on the atomic scale, which requires true atomic resolution capabilities. Under optimum optical settings of the image <em>C</em><sub>S</sub>-corrector (CEOS CETCOR) the point-resolution is extended up to the information limit of well below 100 pm with 200 keV and 300 keV electrons. A special piezo-stage design allows ultra-precise positioning of the specimen in all 3 dimensions. Digital images are acquired with a Gatan 2k x 2k slow-scan charged coupled device camera.

scholarly journals Recent Advances in Solid-State Nuclear Magnetic Resonance Spectroscopy

2018 ◽  
Vol 11 (1) ◽  
pp. 485-508 ◽  
Author(s):  
Sharon E. Ashbrook ◽  
John M. Griffin ◽  
Karen E. Johnston
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
Nmr Spectroscopy ◽  
Magnetic Resonance ◽  
Solid State Nmr ◽  
Spectral Lines ◽  
Atomic Scale ◽  
Resonance Spectroscopy ◽  
Diverse Range ◽  
Nuclear Magnetic

The sensitivity of nuclear magnetic resonance (NMR) spectroscopy to the local atomic-scale environment offers great potential for the characterization of a diverse range of solid materials. Despite offering more information than its solution-state counterpart, solid-state NMR has not yet achieved a similar level of recognition, owing to the anisotropic interactions that broaden the spectral lines and hinder the extraction of structural information. Here, we describe the methods available to improve the resolution of solid-state NMR spectra and the continuing research in this area. We also highlight areas of exciting new and future development, including recent interest in combining experiment with theoretical calculations, the rise of a range of polarization transfer techniques that provide significant sensitivity enhancements, and the progress of in situ measurements. We demonstrate the detailed information available when studying dynamic and disordered solids and discuss the future applications of solid-state NMR spectroscopy across the chemical sciences.

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