Mean square displacements of atoms in cubic metals at melting point

1968 ◽  
Vol 18 (11) ◽  
pp. 1413-1415 ◽  
Author(s):  
S. K. Sangal ◽  
P. K. Sharma
Keyword(s):  
Melting Point ◽  
Mean Square ◽  
Cubic Metals

scholarly journals Melting Criterion for Cubic Metals Based on a Modified Angular Force Model

1974 ◽  
Vol 27 (1) ◽  
pp. 129 ◽  
Author(s):  
Jyoti Prakash ◽  
MP Hemkar
Keyword(s):  
Melting Point ◽  
Periodic Table ◽  
Lattice Dynamics ◽  
Force Model ◽  
Mean Square ◽  
Interatomic Spacing ◽  
Cubic Metals ◽  
The Mean ◽  
Thermal Vibrations

A modified angular force model for the lattice dynamics of metals is used to test Lindemann's melting criterion by computing the ratio Ym of the mean square amplitude of thermal vibrations to the square of the interatomic spacing at the melting point for a number of cubic metals belonging to different groups in the periodic table.

Voids in Irradiated Tungsten and Molybdenum

1969 ◽  
Vol 27 ◽  
pp. 190-191
Author(s):  
Robert C. Rau ◽  
Robert L. Ladd
Keyword(s):  
Melting Point ◽  
Fast Neutron ◽  
Neutron Irradiation ◽  
Elevated Temperatures ◽  
Irradiation Temperature ◽  
The Body ◽  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Cubic Metals ◽  
Face Centered

Recent studies have shown the presence of voids in several face-centered cubic metals after neutron irradiation at elevated temperatures. These voids were found when the irradiation temperature was above 0.3 Tm where Tm is the absolute melting point, and were ascribed to the agglomeration of lattice vacancies resulting from fast neutron generated displacement cascades. The present paper reports the existence of similar voids in the body-centered cubic metals tungsten and molybdenum.

scholarly journals Predicting Melting Points of Biofriendly Choline-Based Ionic Liquids with Molecular Dynamics

2019 ◽  
Vol 9 (24) ◽  
pp. 5367 ◽  
Author(s):  
Karl Karu ◽  
Fred Elhi ◽  
Kaija Põhako-Esko ◽  
Vladislav Ivaništšev
Keyword(s):  
Crystal Structure ◽  
Molecular Dynamics ◽  
Ionic Liquids ◽  
Melting Point ◽  
Chemical Space ◽  
Mean Square ◽  
Melting Points ◽  
Simulation Based ◽  
Predicted Values ◽  
Dynamics Simulations

In this work, we introduce a simulation-based method for predicting the melting point of ionic liquids without prior knowledge of their crystal structure. We run molecular dynamics simulations of biofriendly, choline cation-based ionic liquids and apply the method to predict their melting point. The root-mean-square error of the predicted values is below 24 K. We advocate that such precision is sufficient for designing ionic liquids with relatively low melting points. The workflow for simulations is available for everyone and can be adopted for any species from the wide chemical space of ionic liquids.

The Necessary Duration of a Molecular Dynamics Experiment for the Diffusion Coefficient Calculation

2018 ◽  
Vol 30 ◽  
pp. 22-27
Author(s):  
Gennady M. Poletaev ◽  
Ekaterina S. Medvedeva ◽  
Darya V. Novoselova ◽  
Irina V. Zorya ◽  
Mikhail D. Starostenkov
Keyword(s):  
Molecular Dynamics ◽  
Diffusion Coefficient ◽  
Melting Point ◽  
Hydrogen Atom ◽  
Point Defects ◽  
Interstitial Atom ◽  
Mean Square ◽  
Impurity Atoms ◽  
Metal Crystal

The evaluation of the necessary duration of a molecular dynamics experiment for the calculation of the diffusion coefficient at migration of different point defects in Ni (vacancy, bivacancy, self-interstitial atom, hydrogen atom) is held in the present work. It is shown that at the temperature higher than 0.6 of melting point is usually enough the simulation during of 100 ps for this. When calculating of the diffusion coefficient of impurity in the metal crystal, for example, of hydrogen, the decrease of error of mean-square displacements of impurity atoms can be achieved by introducing of a large number of the impurities.

Krebs's model and Lindemann's melting law

1968 ◽  
Vol 46 (15) ◽  
pp. 1677-1679 ◽  
Author(s):  
A. K. Singh ◽  
P. K. Sharma
Keyword(s):  
Melting Temperature ◽  
Periodic Table ◽  
Lattice Dynamics ◽  
Mean Square Displacement ◽  
Mean Square ◽  
Interatomic Spacing ◽  
Cubic Metals ◽  
The Mean ◽  
Thermal Vibrations

Lindemann's melting criterion for cubic metals is examined using Krebs's model for the lattice dynamics of metals by computing the ratio, xm, of the mean square displacement of thermal vibrations and the square of interatomic spacing at the melting temperature for a number of cubic metals belonging to different groups of the periodic table. This ratio has nearly the same value for elements of one particular group, but exhibits wide variation from one group to another. It is concluded that Lindemann's melting law is inadequate.

scholarly journals Simple Description of Anharmonic Phenomena in Cubic Crystals

1974 ◽  
Vol 27 (6) ◽  
pp. 831 ◽  
Author(s):  
DW Field
Keyword(s):  
Melting Point ◽  
Room Temperature ◽  
Atomic Displacement ◽  
Single Atom ◽  
Spherically Symmetric ◽  
Simple Description ◽  
Cubic Crystals ◽  
Cubic Metals ◽  
Experimental Values ◽  
Atom Potential

A simple spherically symmetric single-atom potential expression in the form of a series expansion in the atomic displacement is assumed to describe the potential energy of each atom in monatomic cubic crystals from room temperature to their melting point. Expressions are derived to account for thermal properties such as melting point and thermal expansion. Calculated results for 13 cubic metals are compared with experimental values. The model accounts for the broad trends in the experimental data and provides an estimate of the extent of anharmonicity to be found in these simple solids.

The Bordeaux Automatic Meridian Circle

1978 ◽  
Vol 48 ◽  
pp. 227-228
Author(s):  
Y. Requième
Keyword(s):  
Mean Square Error ◽  
Mean Square ◽  
Meridian Circle ◽  
The Mean ◽  
Full Automation

In spite of important delays in the initial planning, the full automation of the Bordeaux meridian circle is progressing well and will be ready for regular observations by the middle of the next year. It is expected that the mean square error for one observation will be about ±0.”10 in the two coordinates for declinations up to 87°.

The observation of nano-voids in Au thin films

1987 ◽  
Vol 45 ◽  
pp. 366-367
Author(s):  
William Krakow
Keyword(s):  
Thin Films ◽  
Melting Point ◽  
Present Author ◽  
Stacking Faults ◽  
Damage Threshold ◽  
Ionic Species ◽  
Rare Gases ◽  
Chain Defects ◽  
Vacancy Chains ◽  
Au Thin Films

It has long been known that defects such as stacking faults and voids can be quenched from various alloyed metals heated to near their melting point. Today it is common practice to irradiate samples with various ionic species of rare gases which also form voids containing solidified phases of the same atomic species, e.g. ref. 3. Equivalently, electron irradiation has been used to produce damage events, e.g. ref. 4. Generally all of the above mentioned studies have relied on diffraction contrast to observe the defects produced down to a dimension of perhaps 10 to 20Å. Also all these studies have used ions or electrons which exceeded the damage threshold for knockon events. In the case of higher resolution studies the present author has identified vacancy and interstitial type chain defects in ion irradiated Si and was able to identify both di-interstitial and di-vacancy chains running through the foil.

Sign in / Sign up

Export Citation Format

Share Document