scholarly journals Semi-Experimental Determination of the Linear Clamped Electro-Optical Coefficients of Polar Crystals from Vibrational Spectroscopic Data

Crystals ◽  
2021 ◽  
Vol 12 (1) ◽  
pp. 52
Author(s):  
Eric Bouhari ◽  
Ballo Mohamadou ◽  
Patrice Bourson
Keyword(s):  
First Principles ◽  
Soft Mode ◽  
Dielectric Susceptibility ◽  
First Principles Calculations ◽  
Mode Behavior ◽  
Direct Measurements ◽  
Semi Empirical ◽  
General Method ◽  
Good Agreement

The present work highlights a new general method devoted to computations of the clamped linear electro-optical coefficients from the measured fundamental vibrational frequencies and the nonlinear dielectric susceptibility constants. The calculations are based on the formula analog to that of the Lyddane–Sachs–Teller relation, which is systematically used for the calculations of the clamped linear electro-optical coefficient of oxide ferroelectric crystals such as LiNbO3, LiTaO3, BaTiO3, PbTiO3, and KNbO3. The computed electro-optical coefficients are in good agreement with those obtained from direct measurements and the first-principles calculations or other semi-empirical models. In addition, the famous r51 or r42 coefficients of the tetragonal BaTiO3, PbTiO3, and KNbO3 crystals are finally calculated with high accuracy and discussed in connection with the soft mode behavior.

Determination of spin-wave stiffness in the Fe-Si system using first-principles calculations

2021 ◽  
Vol 104 (6) ◽  
Author(s):  
Matteo Rinaldi ◽  
Matous Mrovec ◽  
Manfred Fähnle ◽  
Ralf Drautz
Keyword(s):  
Spin Wave ◽  
First Principles ◽  
First Principles Calculations

Magnetic and magnetocaloric properties of Ni47Mn40Sn13−xZnx alloys: Direct measurements and first-principles calculations

2020 ◽  
Vol 101 (13) ◽  
Author(s):  
A. Ghotbi Varzaneh ◽  
P. Kameli ◽  
I. Abdolhosseini Sarsari ◽  
M. Ghorbani Zavareh ◽  
C. Salazar Mejía ◽  
...  
Keyword(s):  
First Principles ◽  
First Principles Calculations ◽  
Direct Measurements ◽  
Magnetocaloric Properties

Infrared Spectroscopy of Hydrogen in ZnO

2004 ◽  
Vol 813 ◽  
Author(s):  
M.D. Mccluskey ◽  
S.J. Jokela
Keyword(s):  
First Principles ◽  
Experimental Studies ◽  
Wide Band ◽  
Shallow Donor ◽  
Great Promise ◽  
Bulk Single Crystal ◽  
First Principles Calculations ◽  
Wide Band Gap ◽  
Theoretical Predictions ◽  
Good Agreement

ABSTRACTZinc oxide (ZnO) has shown great promise as a wide band gap semiconductor with optical, electronic, and mechanical applications. Recent first-principles calculations and experimental studies have shown that hydrogen acts as a shallow donor in ZnO, in contrast to hydrogen's usual role as a passivating impurity. The structures of such hydrogen complexes, however, have not been determined. To address this question, we performed vibrational spectroscopy on bulk, single-crystal ZnO samples annealed in hydrogen (H2) or deuterium (D2) gas. Using infrared (IR) spectroscopy, we have observed O-H and O-D stretch modes at 3326.3 cm−1 and 2470.3 cm−1 respectively, at a sample temperature of 14 K. These frequencies are in good agreement with the theoretical predictions for hydrogen and deuterium in an antibonding configuration, although the bond-centered configuration cannot be ruled out. The IR-active hydrogen complexes are unstable, however, with a dissocation barrier on the order of 1 eV.

CASTEP Calculation of Surface Energy of α-Al2O3

2012 ◽  
Vol 512-515 ◽  
pp. 490-493 ◽  
Author(s):  
Yan Yuan Liang ◽  
Da Ming Chen ◽  
Jiang Feng Tong
Keyword(s):  
First Principles ◽  
Growth Habit ◽  
First Principles Calculations ◽  
Crystal Face ◽  
Exchange Correlation ◽  
Calculation Results ◽  
The Face ◽  
Α Al2o3 ◽  
Materials Studio ◽  
Good Agreement

First principles calculations were run on bulk and the （110）（001）（012）（113） surfaces of α-Al2O3 in order to examine the growth habit of α-Al2O3 crystals.The Materials Studio package was used, specifically the program CASTEP, utilizing Perdew Burke Ernzerh of exchange-correlation pseudo-potentials. The calculation results shows that the ranking of the face energy on different crystal face are E(001)‹ E(113) ‹ E(012) ‹E(110) which is in good agreement with experiment phenomenon observed that the ranking of the growth rates of different crystal faces are V(001) ‹ V(113) ‹ V(012) ‹ V(110).

The structural stabilities of the intermetallics and the solid-state phase transformations induced by lattice vibration effects in the Al–Zr system by first-principles calculations

2010 ◽  
Vol 25 (9) ◽  
pp. 1689-1694 ◽  
Author(s):  
Hui Zhang ◽  
Shaoqing Wang
Keyword(s):  
Solid State ◽  
Phase Transformations ◽  
High Temperatures ◽  
First Principles ◽  
Lattice Vibration ◽  
Enthalpies Of Formation ◽  
Phase Transformation Temperature ◽  
First Principles Calculations ◽  
Experimental Phase Diagram ◽  
Good Agreement

We investigated the structural stabilities of the intermetallics and the solid-state phase transformations induced by lattice vibration effects in the Al–Zr system by first-principles calculations. The calculated lattice parameters of all the phases and the phonon dispersion relations for pure Al and Zr are in good agreement with the experimental data. AlZr(oC8), Al4Zr5 (hP18), and Al3Zr5 (tI32) are predicted to be the high-temperature phases. To study the structural stabilities at high temperatures, the thermodynamic properties of the intermetallics are calculated via the linear response approach within the harmonic approximation. Thanks to the calculated enthalpies of formation at high temperatures, Al3Zr5 is predicted to be stabilized above 1163 K with respect to AlZr2 and Al2Zr3, in good agreement with the phase transformation temperature (1273 K) in the experimental phase diagram.

scholarly journals Thermodynamic modeling of the In-Sc and In-Y systems supported by first-principles calculations

2018 ◽  
Vol 54 (2) ◽  
pp. 161-167 ◽  
Author(s):  
Z. Hu ◽  
C. Huang ◽  
J. Tu ◽  
Y. Huang ◽  
A. Dong
Keyword(s):  
Intermetallic Compounds ◽  
Thermodynamic Modeling ◽  
First Principles ◽  
Regular Solution Model ◽  
Calphad Method ◽  
Enthalpies Of Formation ◽  
Thermodynamic Optimization ◽  
First Principles Calculations ◽  
Self Consistent ◽  
Good Agreement

Based on an assessment of the phase equilibria and thermodynamic data in the literature, the thermodynamic modeling of the In?Sc and In?Y systems was carried out by means of the calculation of phase diagram (CALPHAD) method supported by first-principles calculations. The solution phases, i.e., liquid, (In), (?Sc), (?Sc), (?Y) and (?Y), were modeled with the substitutional regular solution model. Ten intermetallic compounds, including InSc3, InSc2, In4Sc5, InSc, In2Sc, In3Sc, InY2, InY, In5Y3, and In3Y were described as stoichiometric phases, while In3Y5 was modeled with a sublattice model with respect to its homogeneity range. The enthalpies of formation of the intermetallic compounds at 0 K were computed using firstprinciple calculations and were used as input for the thermodynamic optimization. A set of self-consistent thermodynamic parameters for both the In?Sc and In?Y systems were obtained and the calculated phase diagrams are in good agreement with the experimental data.

CALCULATIONS OF SELF-DIFFUSION PROCESS AND COEFFICIENT IN ORDERED B2 AlCo

2013 ◽  
Vol 27 (19) ◽  
pp. 1341034
Author(s):  
ZHI-SHENG NONG ◽  
JING-CHUAN ZHU ◽  
YONG CAO ◽  
XIA-WEI YANG ◽  
ZHONG-HONG LAI ◽  
...  
Keyword(s):  
Diffusion Process ◽  
First Principles ◽  
Diffusion Coefficients ◽  
Density Functional ◽  
Nearest Neighbor ◽  
The Self ◽  
First Principles Calculations ◽  
Self Diffusion ◽  
Diffusion Mechanisms ◽  
Semi Empirical

The self-diffusion process in B2 type intermetallic compound AlCo has been investigated by the first-principles calculations within the frame work of density functional theory (DFT). The obtained mono-vacancy formation, migration and activation energies for four self-diffusion mechanisms, the next-nearest-neighbor (NNN) jump, [110] six-jump cycle (6JC), straight [100] 6JC and bent [100] 6JC diffusion show that the NNN jump mechanism of Co vacancy requires the lowest activation energy (Q = 6.835 eV ) in these diffusion mechanisms, which indicates that it is the main way of self-diffusion in AlCo . The electronic structure including the electron density difference on (-1 1 0) plane as well as atomic Mulliken populations were calculated, and the change of bonding behavior during the [110] 6JC process was discussed in detail. Finally, the self-diffusion coefficients of NNN jump and 6JC mechanisms for AlCo were also studied via the first-principles calculations and semi-empirical predictions, which indicates that the self-diffusion coefficients for NNN jump of Co vacancy show the highest value than the others.

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