scholarly journals Folded network and structural transition in molten tin

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Liang Xu ◽  
Zhigang Wang ◽  
Jian Chen ◽  
Songyi Chen ◽  
Wenge Yang ◽  
...  
Keyword(s):  
Disordered Systems ◽  
Structural Transition ◽  
Hard Spheres ◽  
Random Network ◽  
Covalent Bond ◽  
Liquid Structure ◽  
New Paradigm ◽  
Bond Network ◽  
Theoretical Evidence ◽  
Continuous Random Network

AbstractThe fundamental relationships between the structure and properties of liquids are far from being well understood. For instance, the structural origins of many liquid anomalies still remain unclear, but liquid-liquid transitions (LLT) are believed to hold a key. However, experimental demonstrations of LLTs have been rather challenging. Here, we report experimental and theoretical evidence of a second-order-like LLT in molten tin, one which favors a percolating covalent bond network at high temperatures. The observed structural transition originates from the fluctuating metallic/covalent behavior of atomic bonding, and consequently a new paradigm of liquid structure emerges. The liquid structure, described in the form of a folded network, bridges two well-established structural models for disordered systems, i.e., the random packing of hard-spheres and a continuous random network, offering a large structural midground for liquids and glasses. Our findings provide an unparalleled physical picture of the atomic arrangement for a plethora of liquids, shedding light on the thermodynamic and dynamic anomalies of liquids but also entailing far-reaching implications for studying liquid polyamorphism and dynamical transitions in liquids.

The Structure of Ion-Implanted Amorphous Silicon

1998 ◽  
Vol 540 ◽  
Author(s):  
J. M. Gibson ◽  
J-Y. Cheng ◽  
P. Voyles ◽  
M.M.J. TREACY ◽  
D.C. Jacobson
Keyword(s):  
Amorphous Silicon ◽  
Network Model ◽  
Random Network ◽  
Amorphous Semiconductors ◽  
Range Order ◽  
Medium Range Order ◽  
Medium Range ◽  
Large Heat ◽  
Continuous Random Network ◽  
Ion Implanted

AbstractUsing fluctuation microscopy, we show that ion-implanted amorphous silicon has more medium-range order than is expected from the continuous random network model. From our previous work on evaporated and sputtered amorphous silicon, we conclude that the structure is paracrystalline, i.e. it possesses crystalline-like order which decays with distance from any point. The observation might pose an explanation for the large heat of relaxation that is evolved by ion-implanted amorphous semiconductors.

Visualization of tetrahedral disordering in amorphous germanium through local atomic motifs

2018 ◽  
Vol 51 (6) ◽  
pp. 1544-1550
Author(s):  
Aly Rahemtulla ◽  
Bruno Tomberli ◽  
Stefan Kycia
Keyword(s):  
Random Network ◽  
Network Models ◽  
Refined Model ◽  
Amorphous Germanium ◽  
Crystalline Materials ◽  
X Ray ◽  
Alignment Procedure ◽  
X Ray Scattering ◽  
Structural Details ◽  
Continuous Random Network

The atomic arrangements in amorphous solids, unlike those in crystalline materials, remain elusive. The details of atom ordering are under debate even in simplistic random network models. This work presents further advancements in the local atomic motif (LAM) method, first through the introduction of an optimized alignment procedure providing a clearer image of the angular ordering of atoms in a model. Secondly, by applying stereographic projections with LAMs, the angular ordering within coordination shells can be quantified and investigated. To showcase the new capabilities, the LAM method is applied to amorphous germanium, the archetype of covalent amorphous systems. The method is shown to dissect structural details of amorphous germanium (a-Ge) from the continuous random network (CRN) model and a reverse Monte Carlo (RMC) refined model fitted to high-resolution X-ray scattering measurements. The LAMs reveal well defined dihedral ordering in the second shell. The degree of dihedral ordering is observed to be coupled to bond length distances in the CRN model. This coupling is clearly not present within the RMC refined model. The LAMs reveal inclusions of third-shell atoms occupying interstitial positions in the second shell in both models.

Fluctuation Microscopy in the STEM

2001 ◽  
Vol 7 (S2) ◽  
pp. 226-227
Author(s):  
P. M. Voyles ◽  
D. A. Muller
Keyword(s):  
Random Network ◽  
Dark Field ◽  
Distribution Functions ◽  
Disordered Materials ◽  
Microscopy Technique ◽  
Medium Range ◽  
Fluctuation Microscopy ◽  
Image Position ◽  
Continuous Random Network ◽  
Vector Magnitude

Fluctuation microscopy is an electron microscopy technique sensitive to medium-range order (MRO) in disordered materials. It has been applied to study amorphous germanium and silicon, leading to the conclusion that these materials exhibit more MRO than the conventional continuous random network model for their structure.As originally proposed by Treacy and Gibson, fluctuation microscopy utilizes mesoscopicresolution (1.5 nm) hollow-cone dark field (HCDF) imaging in a TEM. The normalized variance of such images,is a measure of the magnitude of fluctuations in the diffracted intensity from mesoscopic volumes of the sample and is sensitive to MRO via the three- and four-body atom distribution functions. Studying V as a function of the diffraction vector magnitude k gives information about the degree of MRO and the internal structure of ordered regions. V as a function of the inverse resolution Q gives information about the characteristic MRO length scale.

Electron and phonon states in an ideal continuous random network model ofa−SiO2glass

1999 ◽  
Vol 59 (5) ◽  
pp. 3540-3550 ◽  
Author(s):  
Ming-Zhu Huang ◽  
Lizhi Ouyang ◽  
W. Y. Ching
Keyword(s):  
Network Model ◽  
Random Network ◽  
Continuous Random Network

Relaxed continuous random network models (II)

1975 ◽  
Vol 17 (3) ◽  
pp. 299-318 ◽  
Author(s):  
J.F. Graczyk ◽  
P. Chaudhari
Keyword(s):  
Random Network ◽  
Network Models ◽  
Continuous Random Network

Relaxed continuous random network models

1974 ◽  
Vol 15 (2) ◽  
pp. 199-214 ◽  
Author(s):  
P Steinhardt ◽  
R Alben ◽  
D Weaire
Keyword(s):  
Random Network ◽  
Network Models ◽  
Continuous Random Network

Electron States in Static Disordered Systems and Fluid Systems

1991 ◽  
Vol 02 (01) ◽  
pp. 305-309
Author(s):  
L. CRUZEIRO-HANSSON ◽  
J.O. BAUM ◽  
J.L. FINNEY
Keyword(s):  
Path Integral ◽  
Disordered Systems ◽  
Hard Spheres ◽  
Quantum Statistical Mechanics ◽  
Structural Disorder ◽  
Path Integral Formulation ◽  
Electron States ◽  
Fluid Systems ◽  
Fluid Environment ◽  
Quantum Statistical

The path integral formulation of quantum statistical mechanics is used to study the effect of structural disorder on the electron states at finite temperatures. The following systems are investigated: an excess electron in a) a perfect hard spheres crystal, b) a hard spheres crystal with a vacancy and c) a hard spheres fluid. The localizing effect of a vacancy on the electron equals that of a fluid environment.

Structural properties of liquid aluminosilicate with varying Al2O3/SiO2 ratios: Insight from analysis and visualization of molecular dynamics data

2017 ◽  
Vol 31 (05) ◽  
pp. 1750036 ◽  
Author(s):  
N. V. Yen ◽  
M. T. Lan ◽  
L. T. Vinh ◽  
N. V. Hong
Keyword(s):  
Molecular Dynamics ◽  
Random Network ◽  
Md Simulations ◽  
Degree Of Polymerization ◽  
Distribution Functions ◽  
Molar Ratio ◽  
Nonbridging Oxygen ◽  
Structural Units ◽  
Self Diffusion ◽  
Continuous Random Network

Molecular dynamics (MD) simulations and visualizations were explored to investigate the changes in structure of liquid aluminosilicates. The models were constructed for four compositions with varying Al2O3/SiO2 ratio. The local structure and network topology was analyzed through the pair of radial distribution functions, bond angle, bond length and coordination number distributions. The results showed that the structure of aluminosilicates mainly consists of the basic structural units TO[Formula: see text] (T is Al or Si; y = 3, 4, 5). Two adjacent units TO[Formula: see text] are linked to each other through common oxygen atoms and form continuous random network of basic structural units TO[Formula: see text]. The bond statistics (corner-, edge- and face- sharing) between two adjacent TO[Formula: see text] units are investigated in detail. The self-diffusion coefficients for three atomic types are affected by the degree of polymerization (DOP) of network characterized by the proportions of nonbridging oxygen (NBO) and Q[Formula: see text] species in the system. It was found that Q4 and Q3 tetrahedral species (tetrahedron with four and three bridging oxygens, respectively) decreases, while Q0 (with four nonbridging oxygen) increase with increasing Al2O3/SiO2 molar ratio, suggesting that a less polymerized network was formed. The structural and dynamical heterogeneities, micro-phase separation and liquid–liquid phase transition are also discussed in this work.

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