Abdullah Al-Barakati | Umm Al-Qura University, Makkah, Saudi Arabia (original) (raw)
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Papers by Abdullah Al-Barakati
Physical Review B, 2015
ABSTRACT
Applied Mathematics & Information Sciences
... A 41, (2008) 185304. [16] A.-SF Obada,HA Hessian and A.-BA Mohamed Opt. Commun. ... 131 Abdul... more ... A 41, (2008) 185304. [16] A.-SF Obada,HA Hessian and A.-BA Mohamed Opt. Commun. ... 131 Abdullah Albarakati is an assistance professor at Physics De-partment, Umm Al-Qura University in Saudi Arabia, and He is recently the chairman of Physics Department. ...
... Abstract: K1.00030 : Finite-temperature properties of PMN-PT from atomistic simulations. Prev... more ... Abstract: K1.00030 : Finite-temperature properties of PMN-PT from atomistic simulations. Preview Abstract. Authors: Abdullah Al-Barakaty (Umm Al-Qura University). Sergey Prosandeev (University of Arkansas). Laurent Bellaiche (University of Arkansas). ...
International Journal of Modern Physics B, 2013
Physical Review B, 2003
A global picture for the structural evolution in the relaxor-ferroelectric solid solution (PbSc1/... more A global picture for the structural evolution in the relaxor-ferroelectric solid solution (PbSc1/2Nb1/2O3)1-x-(PbTiO3)x is proposed. Thanks to x-ray profile analysis and Rietveld neutron powder refinement, a monoclinic phase has been evidenced in the morphotropic region (i.e., x≈0.43). This lower-symmetry phase ``bridges'' the rhombohedral Ti-poor phase (x0.55), in a similar way as in PbMg1/3Nb2/3O3-PbTiO3 or Pb(Zn1/3Nb2/3)O3-PbTiO3. For weak titanium concentration, we
Physical Review Letters, 2012
A first-principles-based technique is developed to investigate the properties of Ba(Zr,Ti)O(3) re... more A first-principles-based technique is developed to investigate the properties of Ba(Zr,Ti)O(3) relaxor ferroelectrics as a function of temperature. The use of this scheme provides answers to important, unresolved and/or controversial questions such as the following. What do the different critical temperatures usually found in relaxors correspond to? Do polar nanoregions really exist in relaxors? If yes, do they only form inside chemically ordered regions? Is it necessary that antiferroelectricity develop in order for the relaxor behavior to occur? Are random fields and random strains really the mechanisms responsible for relaxor behavior? If not, what are these mechanisms? These ab initio based calculations also lead to deep microscopic insight into relaxors.
Physical Review B, 2005
X-ray and neutron diffraction techniques are combined with first-principles-based simulations to ... more X-ray and neutron diffraction techniques are combined with first-principles-based simulations to derive and understand the structural properties of Pb(Sc,Nb,Ti)O3 (PSN-PT) near its morphotropic phase boundary (MPB). An analysis of our measurements yields, at room and low temperatures, an overall tetragonal T ---monoclinic MC ---monoclinic MB ---rhombohedral R path (when adopting the notations of Vanderbilt and Cohen, Phys. Rev. B 63, 94108 (2001) for the monoclinic phases) as the Ti composition decreases across the MPB. A composition- and temperature-dependent significant mixing between some of these phases is also measured and reported here. The overall T-MC-MB-R path, which has also been proposed for Pb(Mg,Nb,Ti)O3 [A. K. Singh and D. Pandey, Phys. Rev. B 67, 64102 (2003)] is rather complex since it involves a change in the polarization path: this polarization first rotates in a (100) plane for the T-MC part of the path and then in a (1-10) plane for the MB-R part of the path. Moreover, a comparison between these measurements and first-principles-based calculations raises the possibility that this complex path, and the associated MC and MB phases, can only occur if the samples exhibit a deviation from a perfectly homogeneous and disordered situation, e.g. possess nanoscale chemically-ordered regions. If not, homogeneously disordered PSN-PT is predicted to exhibit at low temperature the same polarization path as Pb(Zr,Ti)O3 , that is T -monoclinic MA-R which involves a ``single'' polarization rotation in a (1-10) plane. Nanoscale inhomogeneity may thus play a key role on the macroscopic properties of PSN-PT, in particular, and of other heterovalent complex solid solutions, in general, near their MPB.
Physical Review B, 2009
Via a combination of various experimental and theoretical techniques, a peculiar, identical tempe... more Via a combination of various experimental and theoretical techniques, a peculiar, identical temperature scale T* is found to exist in all complex lead-based relaxor ferroelectrics studied by us. T* corresponds to a nanoscale phase transition associated with random fields. Interestingly, T* also exists in other oxides with extraordinary properties, such as giant magnetoresistivity or superconductivity. By analogy with such latter
Phase Transitions, 2006
We have recently evidenced the existence of a complex path of polarisation rotation via two monoc... more We have recently evidenced the existence of a complex path of polarisation rotation via two monoclinic phases in the giant-piezoelectric materials PSN–PT that is similar to the PMN–PT system. In this article we have presented the state of knowledge on the PSN–PT system and have given new results showing the close connection between the local inhomogeneous chemical order of Sc/Nb/Ti
Applied Physics Letters, 2002
ABSTRACT
Physical Review B, 2015
ABSTRACT
Applied Mathematics & Information Sciences
... A 41, (2008) 185304. [16] A.-SF Obada,HA Hessian and A.-BA Mohamed Opt. Commun. ... 131 Abdul... more ... A 41, (2008) 185304. [16] A.-SF Obada,HA Hessian and A.-BA Mohamed Opt. Commun. ... 131 Abdullah Albarakati is an assistance professor at Physics De-partment, Umm Al-Qura University in Saudi Arabia, and He is recently the chairman of Physics Department. ...
... Abstract: K1.00030 : Finite-temperature properties of PMN-PT from atomistic simulations. Prev... more ... Abstract: K1.00030 : Finite-temperature properties of PMN-PT from atomistic simulations. Preview Abstract. Authors: Abdullah Al-Barakaty (Umm Al-Qura University). Sergey Prosandeev (University of Arkansas). Laurent Bellaiche (University of Arkansas). ...
International Journal of Modern Physics B, 2013
Physical Review B, 2003
A global picture for the structural evolution in the relaxor-ferroelectric solid solution (PbSc1/... more A global picture for the structural evolution in the relaxor-ferroelectric solid solution (PbSc1/2Nb1/2O3)1-x-(PbTiO3)x is proposed. Thanks to x-ray profile analysis and Rietveld neutron powder refinement, a monoclinic phase has been evidenced in the morphotropic region (i.e., x≈0.43). This lower-symmetry phase ``bridges'' the rhombohedral Ti-poor phase (x0.55), in a similar way as in PbMg1/3Nb2/3O3-PbTiO3 or Pb(Zn1/3Nb2/3)O3-PbTiO3. For weak titanium concentration, we
Physical Review Letters, 2012
A first-principles-based technique is developed to investigate the properties of Ba(Zr,Ti)O(3) re... more A first-principles-based technique is developed to investigate the properties of Ba(Zr,Ti)O(3) relaxor ferroelectrics as a function of temperature. The use of this scheme provides answers to important, unresolved and/or controversial questions such as the following. What do the different critical temperatures usually found in relaxors correspond to? Do polar nanoregions really exist in relaxors? If yes, do they only form inside chemically ordered regions? Is it necessary that antiferroelectricity develop in order for the relaxor behavior to occur? Are random fields and random strains really the mechanisms responsible for relaxor behavior? If not, what are these mechanisms? These ab initio based calculations also lead to deep microscopic insight into relaxors.
Physical Review B, 2005
X-ray and neutron diffraction techniques are combined with first-principles-based simulations to ... more X-ray and neutron diffraction techniques are combined with first-principles-based simulations to derive and understand the structural properties of Pb(Sc,Nb,Ti)O3 (PSN-PT) near its morphotropic phase boundary (MPB). An analysis of our measurements yields, at room and low temperatures, an overall tetragonal T ---monoclinic MC ---monoclinic MB ---rhombohedral R path (when adopting the notations of Vanderbilt and Cohen, Phys. Rev. B 63, 94108 (2001) for the monoclinic phases) as the Ti composition decreases across the MPB. A composition- and temperature-dependent significant mixing between some of these phases is also measured and reported here. The overall T-MC-MB-R path, which has also been proposed for Pb(Mg,Nb,Ti)O3 [A. K. Singh and D. Pandey, Phys. Rev. B 67, 64102 (2003)] is rather complex since it involves a change in the polarization path: this polarization first rotates in a (100) plane for the T-MC part of the path and then in a (1-10) plane for the MB-R part of the path. Moreover, a comparison between these measurements and first-principles-based calculations raises the possibility that this complex path, and the associated MC and MB phases, can only occur if the samples exhibit a deviation from a perfectly homogeneous and disordered situation, e.g. possess nanoscale chemically-ordered regions. If not, homogeneously disordered PSN-PT is predicted to exhibit at low temperature the same polarization path as Pb(Zr,Ti)O3 , that is T -monoclinic MA-R which involves a ``single'' polarization rotation in a (1-10) plane. Nanoscale inhomogeneity may thus play a key role on the macroscopic properties of PSN-PT, in particular, and of other heterovalent complex solid solutions, in general, near their MPB.
Physical Review B, 2009
Via a combination of various experimental and theoretical techniques, a peculiar, identical tempe... more Via a combination of various experimental and theoretical techniques, a peculiar, identical temperature scale T* is found to exist in all complex lead-based relaxor ferroelectrics studied by us. T* corresponds to a nanoscale phase transition associated with random fields. Interestingly, T* also exists in other oxides with extraordinary properties, such as giant magnetoresistivity or superconductivity. By analogy with such latter
Phase Transitions, 2006
We have recently evidenced the existence of a complex path of polarisation rotation via two monoc... more We have recently evidenced the existence of a complex path of polarisation rotation via two monoclinic phases in the giant-piezoelectric materials PSN–PT that is similar to the PMN–PT system. In this article we have presented the state of knowledge on the PSN–PT system and have given new results showing the close connection between the local inhomogeneous chemical order of Sc/Nb/Ti
Applied Physics Letters, 2002
ABSTRACT