scholarly journals Texture parameter variation region for orthotropic polycrystals with cubic symmetry of the crystal lattice

2018 ◽  
Author(s):  
S. A. Berestova ◽  
N. P. Kopytov ◽  
N. E. Misura ◽  
E. A. Mityushov
Author(s):  
P. A. Sechenykh

Information about the structure and properties of materials is especially important when working with micro-and nanoscale objects due to the high complexity of their obtaining. This makes it relevant to use computer modeling to predict the required characteristics of materials. Electronic, magnetic, mechanical, and other properties of crystalline substances are determined by their structure-the periodicity of the lattice and the symmetry of the unit cell. This article discusses metal oxides with the general chemical formulas MeO (metals: Ca, Cd, Mg), MeO2 (metals: Hf, Ce, Zr), Me2O3 (metals: Er, Nd, Sc, Mn, Tl) and Me3O4 (using Fe as an example) and a cubic symmetry type crystal lattice — structural types NaCl (rock salt), Fluorite, Bixbyite, Spinel accordingly. The paper describes the model of ion-atomic radii, which is widely used in the modeling of crystalline metal oxides. The application of the annealing simulation algorithm for calculating the metric parameters of the compounds under consideration is shown. The software implementation of the algorithm presented in this paper allows us to determine the coordinates of the atoms that are included in the elementary cell of the crystal lattice, calculate the lattice constant and the density of the packing of atoms in the crystal cell using the specified chemical formula and the space group symmetry. These structural characteristics can be used as input parameters for determining electronic, magnetic, and other properties. The article compares the values of lattice constants obtained as a result of modeling with experimental data.


2017 ◽  
Vol 23 ◽  
pp. 167-176
Author(s):  
Mikhail Starostenkov ◽  
Pavel Tabakov ◽  
Veronika Romanenko ◽  
Evgeniya Chernykh

Author(s):  
Mikhail D. Starostenkov ◽  
Oleg V. Yashin ◽  
Alexander V. Yashin

In this work, the authors attempted to consider the influence of the geometry of the crystal lattice on the properties of nanowires, which manifest themselves in the process of uni-axial stretching. This work summarizes and systematizes the results of previous studies of the authors. The first group of samples – are typical FCC metal – Ni3Al. For these nanowires, deformation processes in directions with different packing densities of atoms <100>, <110> and <111> were investigated. The second material group studied was an alloy with the non-cubic symmetry of the element cell CuAu I. Correspondingly, this sample was examined under deformation in directions corresponding to different lengths of the sides of the unit cell, <001> and <010>. All the investigations described in this paper were carried out by molecular dynamics method on three-dimensional models using the Morse's pair potentials.


Author(s):  
Wenwu Cao

Domain structures play a key role in determining the physical properties of ferroelectric materials. The formation of these ferroelectric domains and domain walls are determined by the intrinsic nonlinearity and the nonlocal coupling of the polarization. Analogous to soliton excitations, domain walls can have high mobility when the domain wall energy is high. The domain wall can be describes by a continuum theory owning to the long range nature of the dipole-dipole interactions in ferroelectrics. The simplest form for the Landau energy is the so called ϕ model which can be used to describe a second order phase transition from a cubic prototype,where Pi (i =1, 2, 3) are the components of polarization vector, α's are the linear and nonlinear dielectric constants. In order to take into account the nonlocal coupling, a gradient energy should be included, for cubic symmetry the gradient energy is given by,


1978 ◽  
Vol 3 ◽  
pp. 479-501 ◽  
Author(s):  
E. Du Trémolet de Lacheisserie ◽  
P. Morin ◽  
J. Rouchy

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