Bond-stretching and bond-bending force constant of binary tetrahedral (AIIIBV and AIIBVI) semiconductors

2008 ◽  
Vol 372 (48) ◽  
pp. 7196-7198 ◽  
Author(s):  
A.S. Verma
Keyword(s):  
Force Constant ◽  
Bending Force ◽  
Bond Stretching ◽  
Bond Bending

Vibrational, mechanical and thermodynamical properties of RE2Ti2O7 (RE = Sm, Gd, Dy, Ho, Er and Yb) pyrochlores

2017 ◽  
Vol 31 (21) ◽  
pp. 1750145
Author(s):  
A. K. Kushwaha
Keyword(s):  
Bond Strength ◽  
Bulk Modulus ◽  
Force Constant ◽  
Present Calculation ◽  
Neighbor Interaction ◽  
Thermodynamical Properties ◽  
Bending Force ◽  
Young’S Moduli ◽  
Bond Bending ◽  
The One

Vibrational, mechanical, thermodynamical properties and thermal conductivities of RE2Ti2O7 (RE = Sm, Gd, Dy, Ho, Er and Yb) pyrochlores have been calculated using a proposed eight-parameter bond-bending force constant model. The main outcome of present calculation is that the first neighbor interaction (Ti–O) is stronger than the second neighbor interactions (RE–O). This means that the bonding between Ti and O is more ionic than the one between RE and O. It is also found that the bond strength of RE–O and the bulk modulus decrease in the sequence Sm [Formula: see text] Gd [Formula: see text] Dy [Formula: see text] Ho [Formula: see text] Er [Formula: see text] Yb. The bulk moduli and Young’s moduli of RE2Ti2O7 also decrease when RE changes from Sm to Yb.

Relations between Varshni and Morse potential energy parameters

Open Physics ◽  
2009 ◽  
Vol 7 (1) ◽  
Author(s):  
Teik-Cheng Lim ◽  
Rajendra Udyavara
Keyword(s):  
Potential Energy ◽  
Force Constant ◽  
Morse Potential ◽  
Morse Function ◽  
Energy Integral ◽  
Equal Energy ◽  
Molecular Force ◽  
Parameter Conversion ◽  
Bond Stretching ◽  
Small Change

AbstractA set of relationships between the Morse and Varshni potential functions for describing covalent bondstretching energy has been developed by imposing equal force constant and equal energy integral. In view of the extensive adoption of Morse function in molecular force fields, this paper suggests two sets of parameter conversions from Varshni to Morse. The parameter conversion based on equal force constant is applicable for small change in bond length, while the parameter conversion based on equal energy integral is more applicable for significant bond-stretching. Plotted results reveal that the Varshni potential function is more suitable for describing hard bonds rather than soft bonds.

Lattice dynamics of ZnTe, CdTe, GaP, and InP

1980 ◽  
Vol 58 (3) ◽  
pp. 351-358 ◽  
Author(s):  
M. S. Kushwaha ◽  
S. S. Kushwaha
Keyword(s):  
Lattice Dynamics ◽  
Present Model ◽  
Phonon Dispersion ◽  
Model Parameters ◽  
Force Model ◽  
Phonon Dispersion Curves ◽  
Bending Force ◽  
Zinc Blende ◽  
Bond Bending ◽  
Good Agreement

An eight-parameter bond-bending force model (BBFM), recently developed by us for zinc-blende (ZB) structure, has been used to study the lattice dynamics of other compounds of the II–VI and III–V groups. The model parameters were calculated using six critical point phonon frequencies, two elastic constants, and the lattice equilibrium condition. Phonon dispersion curves, phonon density of states, and Debye-characteristic temperatures have been calculated. The comparison of theoretical and the available experimental results reveals a fairly good agreement. The merits and demerits of the present model have been discussed in full.

Mechanisms and measures for the ductility of materials failure

2020 ◽  
Vol 476 (2239) ◽  
pp. 20190719
Author(s):  
Richard M. Christensen
Keyword(s):  
Brittle Failure ◽  
Periodic Table ◽  
Operational Definition ◽  
Atomic Scale ◽  
Brittle Transition ◽  
Bond Stretching ◽  
Bond Bending ◽  
Materials Failure

An operational definition for the ductility of failure is given. Many examples illustrate the procedure for specific applications. The ductile/brittle transition is an integral part of the formalism. Further applications are made to the solids forming elements in the Periodic Table. The cases of graphene and diamond are used to verify the procedure. Bond bending and bond stretching are shown to provide an atomic scale criterion for ductile versus brittle failure behaviours.

Kinematical evaluation of force constants: application to trihalides of phosphorus and arsenic

1970 ◽  
Vol 23 (5) ◽  
pp. 881 ◽  
Author(s):  
SN Rai ◽  
SN Thakur
Keyword(s):  
Force Constant ◽  
Vibrational Frequencies ◽  
Force Constants ◽  
Arbitrary Parameter ◽  
Two Dimensional ◽  
Matrix Elements ◽  
Bending Force ◽  
Symmetry Species

The F-matrix elements for the two-dimensional symmetry species are dependent on one arbitrary parameter in addition to the vibrational frequencies. This parameter has been chosen as an angle � (0 ≤ � ≤ 2π) and the F-matrix elements for the A1- and the E-species of trihalides of phosphorus and arsenic have been studied as functions of �. It is found that the best values of the force constants obtained from Coriolis 1; constants can be correlated with those values of the angle ξ for which the bending force constant exhibits a minimum.

scholarly journals INTERATOMIC INTERACTIONS AND ZONE CENTRE PHONONS IN MULTIFERROIC BiFeO3 CERAMICS

2013 ◽  
Vol 22 ◽  
pp. 134-139 ◽  
Author(s):  
M. M. SINHA ◽  
RUBY ◽  
H. C. GUPTA
Keyword(s):  
Force Constant ◽  
Ferroelectric Properties ◽  
Compressive Strain ◽  
Potential Energy Distribution ◽  
Bending Force ◽  
Short Range Force ◽  
Multiferroic Bifeo3 ◽  
Zone Centre ◽  
Range Force ◽  
Good Agreement

The existence of an epitaxially stabilized tetragonal-like (“T -like”) monoclinic phase in BiFeO 3 thin films with high levels of compressive strain has been reported recently. While their structural and ferroelectric properties are different from those of rhombohedral-like (“R-like”) films with lower levels of strain, little information exists on magnetic properties. In this study we have applied a short range force constant model by using normal coordinates to investigate the Raman and the infrared wavenumbers in tetragonal BiFeO 3 having space group P4mm (C4v1). The calculation of zone center phonons has been made by using three stretching and six bending force constants. The calculated Raman and infrared wavenumbers are in very good agreement with the observed ones. The potential energy distribution has also been investigated for determining the significance of contribution from each force constant toward the Raman and the infrared wavenumbers.

Sign in / Sign up

Export Citation Format

Share Document