Alireza Akbarzadeh
University of California, Los Angeles
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Featured researches published by Alireza Akbarzadeh.
Physical Review B | 2005
Alireza Akbarzadeh; Igor Kornev; C. Malibert; L. Bellaiche; J. M. Kiat
Low temperature properties of BaZrO3 are revealed by combining experimental techniques (X-ray diffraction, neutron scattering and dielectric measurements) with theoretical first-principles-based methods (total energy and linear response calculations within density functional theory, and effective Hamiltonian approaches incorporating/neglecting zero-point phonon vibrations). Unlike most of the perovskite systems, BaZrO3 does not undergo any (long-range-order) structural phase transition and thus remains cubic and paraelectric down to 2 K, even when neglecting zero-point phonon vibrations. On the other hand, these latter pure quantum effects lead to a negligible thermal dependency of the cubic lattice parameter below ~ 40 K. They also affect the dielectricity of BaZrO3 by inducing an overall saturation of the real part of the dielectric response, for temperatures below ~ 40 K. Two fine structures in the real part, as well as in the imaginary part, of dielectric response are further observed around 50-65 K and 15 K, respectively. Microscopic origins (e.g., unavoidable defects and oxygen octahedra rotation occurring at a local scale) of such anomalies are suggested. Finally, possible reasons for the facts that some of these dielectric anomalies have not been previously reported in the better studied KTaO3 and SrTiO3 incipient ferroelectrics are also discussed.
ChemInform | 2009
V. Ozolins; Alireza Akbarzadeh; H Gunaydin; K Michel; C. Wolverton; Eric H. Majzoub
Hydrogen-fuelled vehicles require a cost-effective, lightweight material with precisely targeted thermodynamics and fast kinetics of hydrogen release. Since none of the conventional metal hydrides satisfy the multitude of requirements for a practical H2 storage system, recent research efforts have turned to advanced multicomponent systems based on complex hydrides. We show that first-principles density-functional theory (DFT) calculations have become a valuable tool for understanding and predicting novel hydrogen storage materials and understanding the atomic-scale kinetics of hydrogen release. Recent studies have used DFT calculations to (i) predict crystal structures of new solid-state hydrides, (ii) determine phase diagrams and thermodynamically favoured reaction pathways in multinary hydrides, and (iii) study microscopic kinetics of diffusion, phase transformations, and hydrogen release.
Physical Review B | 2005
Alireza Akbarzadeh; Igor Kornev; Charlotte Malibert; L. Bellaiche; J. M. Kiat
Low temperature properties of BaZrO3 are revealed by combining experimental techniques (X-ray diffraction, neutron scattering and dielectric measurements) with theoretical first-principles-based methods (total energy and linear response calculations within density functional theory, and effective Hamiltonian approaches incorporating/neglecting zero-point phonon vibrations). Unlike most of the perovskite systems, BaZrO3 does not undergo any (long-range-order) structural phase transition and thus remains cubic and paraelectric down to 2 K, even when neglecting zero-point phonon vibrations. On the other hand, these latter pure quantum effects lead to a negligible thermal dependency of the cubic lattice parameter below ~ 40 K. They also affect the dielectricity of BaZrO3 by inducing an overall saturation of the real part of the dielectric response, for temperatures below ~ 40 K. Two fine structures in the real part, as well as in the imaginary part, of dielectric response are further observed around 50-65 K and 15 K, respectively. Microscopic origins (e.g., unavoidable defects and oxygen octahedra rotation occurring at a local scale) of such anomalies are suggested. Finally, possible reasons for the facts that some of these dielectric anomalies have not been previously reported in the better studied KTaO3 and SrTiO3 incipient ferroelectrics are also discussed.
Advanced Materials | 2007
Alireza Akbarzadeh; Vidvuds Ozoliņš; C. Wolverton
Journal of Physics: Condensed Matter | 2008
C. Wolverton; Donald J. Siegel; Alireza Akbarzadeh; V. Ozoli
Physical Review B | 2009
Alireza Akbarzadeh; C. Wolverton; V. Ozolins
Journal of Physical Chemistry C | 2009
Kyle Michel; Alireza Akbarzadeh; V. Ozolins
Physical Review B | 2011
Wenhao Q. Sun; C. Wolverton; Alireza Akbarzadeh; Vidvuds Ozolins
Physical Review B | 2018
Alireza Akbarzadeh; Kumar Brajesh; Yousra Nahas; Naveen Kumar; Sergei Prokhorenko; Diptikanta Swain; Sergey Prosandeev; Raymond Walter; Igor Kornev; Jorge Íñiguez; Brahim Dkhil; Rajeev Ranjan; L. Bellaiche
Bulletin of the American Physical Society | 2018
Yousra Nahas; Alireza Akbarzadeh; Sergei Prokhorenko; Sergey Prosandeev; Raymond Walter; Igor Kornev; Jorge Íñiguez; L. Bellaiche