The Experts below are selected from a list of 89664 Experts worldwide ranked by ideXlab platform
M I Katsnelson - One of the best experts on this subject based on the ideXlab platform.
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ab initio study of interacting lattice vibrations and stabilization of the Beta Phase in ni ti shape memory alloy
Physical Review B, 2010Co-Authors: Petros Souvatzis, Dominik Legut, Olle Eriksson, M I KatsnelsonAbstract:Lattice dynamical methods used to predict Phase transformations in crystals typically evaluate the harmonic phonon spectra and therefore do not work in frequent and important situations where the crystal structure is unstable in the harmonic approximation, such as the $\ensuremath{\Beta}$ structure when it appears as a high-temperature Phase of the shape memory alloy Ni-Ti. Here it is shown by self-consistent ab initio lattice dynamical calculations that the critical temperature for the premartensitic $R$-to-$\ensuremath{\Beta}$ Phase transformation in Ni-Ti can be effectively calculated with good accuracy, and that the $\ensuremath{\Beta}$ Phase is a result primarily of the stabilizing interaction between different lattice vibrations.
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ab initio study of interacting lattice vibrations and stabilization of the Beta Phase in ni ti shape memory alloy
Physical Review B, 2010Co-Authors: Petros Souvatzis, Dominik Legut, Olle Eriksson, M I KatsnelsonAbstract:Lattice dynamical methods used to predict Phase transformations in crystals typically evaluate the harmonic phonon spectra and therefore do not work in frequent and important situations where the crystal structure is unstable in the harmonic approximation, such as the Beta structure when it appears as a high-temperature Phase of the shape memory alloy Ni-Ti. Here it is shown by self-consistent ab initio lattice dynamical calculations that the critical temperature for the premartensitic R-to-Beta Phase transformation in Ni-Ti can be effectively calculated with good accuracy, and that the Beta Phase is a result primarily of the stabilizing interaction between different lattice vibrations.
G Marschick - One of the best experts on this subject based on the ideXlab platform.
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multiferroic bismuth ferrite perturbed angular correlation studies on its ferroic α β Phase transition
Physical Review B, 2020Co-Authors: G Marschick, Juliana Schell, Bernhard Stoger, Joao Goncalves, Maksim O Karabasov, D Zyabkin, A Welker, D GartnerAbstract:Work of numerous research groups has shown different outcomes of studies of the transition from the ferroelectric $\ensuremath{\alpha}$-Phase to the high temperature $\ensuremath{\Beta}$-Phase of the multiferroic, magnetoelectric perovskite Bismuth Ferrite (${\mathrm{BiFeO}}_{3}$ or BFO). Using the perturbed angular correlation (PAC) method with $^{111m}\mathrm{Cd}$ as the probe nucleus, the $\ensuremath{\alpha}$ to $\ensuremath{\Beta}$ Phase transition was characterized. The Phase transition temperature, the change of the crystal structure, and its parameters were supervised with measurements at different temperatures using a six detector PAC setup to observe the $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ decay of the $^{111m}\mathrm{Cd}$ probe nucleus. The temperature dependence of the hyperfine parameters shows a change in coordination of the probe ion, which substitutes for the bismuth site, forecasting the Phase transition to $\ensuremath{\Beta}$-BFO by either increasing disorder or formation of a polytype transition structure. A visible drop of the quadrupole frequency ${\ensuremath{\omega}}_{0}$ at a temperature of about ${T}_{c}\ensuremath{\approx}{820}^{\ensuremath{\circ}}\phantom{\rule{0.16em}{0ex}}\mathrm{C}$ indicates the $\ensuremath{\alpha}\ensuremath{-}\ensuremath{\Beta}$ Phase transition. For a given crystal symmetry, the DFT-calculations yield a specific local symmetry and electric field gradient value of the probe ion. The $Pbnm$ ($\ensuremath{\Beta}$-BFO) crystal symmetry yields calculated local electric field gradients, which very well match our experimental results. The assumption of other crystal symmetries results in significantly different computed local environments not corresponding to the experiment.
Dominik Legut - One of the best experts on this subject based on the ideXlab platform.
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ab initio study of interacting lattice vibrations and stabilization of the Beta Phase in ni ti shape memory alloy
Physical Review B, 2010Co-Authors: Petros Souvatzis, Dominik Legut, Olle Eriksson, M I KatsnelsonAbstract:Lattice dynamical methods used to predict Phase transformations in crystals typically evaluate the harmonic phonon spectra and therefore do not work in frequent and important situations where the crystal structure is unstable in the harmonic approximation, such as the $\ensuremath{\Beta}$ structure when it appears as a high-temperature Phase of the shape memory alloy Ni-Ti. Here it is shown by self-consistent ab initio lattice dynamical calculations that the critical temperature for the premartensitic $R$-to-$\ensuremath{\Beta}$ Phase transformation in Ni-Ti can be effectively calculated with good accuracy, and that the $\ensuremath{\Beta}$ Phase is a result primarily of the stabilizing interaction between different lattice vibrations.
-
ab initio study of interacting lattice vibrations and stabilization of the Beta Phase in ni ti shape memory alloy
Physical Review B, 2010Co-Authors: Petros Souvatzis, Dominik Legut, Olle Eriksson, M I KatsnelsonAbstract:Lattice dynamical methods used to predict Phase transformations in crystals typically evaluate the harmonic phonon spectra and therefore do not work in frequent and important situations where the crystal structure is unstable in the harmonic approximation, such as the Beta structure when it appears as a high-temperature Phase of the shape memory alloy Ni-Ti. Here it is shown by self-consistent ab initio lattice dynamical calculations that the critical temperature for the premartensitic R-to-Beta Phase transformation in Ni-Ti can be effectively calculated with good accuracy, and that the Beta Phase is a result primarily of the stabilizing interaction between different lattice vibrations.
Petros Souvatzis - One of the best experts on this subject based on the ideXlab platform.
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ab initio study of interacting lattice vibrations and stabilization of the Beta Phase in ni ti shape memory alloy
Physical Review B, 2010Co-Authors: Petros Souvatzis, Dominik Legut, Olle Eriksson, M I KatsnelsonAbstract:Lattice dynamical methods used to predict Phase transformations in crystals typically evaluate the harmonic phonon spectra and therefore do not work in frequent and important situations where the crystal structure is unstable in the harmonic approximation, such as the $\ensuremath{\Beta}$ structure when it appears as a high-temperature Phase of the shape memory alloy Ni-Ti. Here it is shown by self-consistent ab initio lattice dynamical calculations that the critical temperature for the premartensitic $R$-to-$\ensuremath{\Beta}$ Phase transformation in Ni-Ti can be effectively calculated with good accuracy, and that the $\ensuremath{\Beta}$ Phase is a result primarily of the stabilizing interaction between different lattice vibrations.
-
ab initio study of interacting lattice vibrations and stabilization of the Beta Phase in ni ti shape memory alloy
Physical Review B, 2010Co-Authors: Petros Souvatzis, Dominik Legut, Olle Eriksson, M I KatsnelsonAbstract:Lattice dynamical methods used to predict Phase transformations in crystals typically evaluate the harmonic phonon spectra and therefore do not work in frequent and important situations where the crystal structure is unstable in the harmonic approximation, such as the Beta structure when it appears as a high-temperature Phase of the shape memory alloy Ni-Ti. Here it is shown by self-consistent ab initio lattice dynamical calculations that the critical temperature for the premartensitic R-to-Beta Phase transformation in Ni-Ti can be effectively calculated with good accuracy, and that the Beta Phase is a result primarily of the stabilizing interaction between different lattice vibrations.
D Gartner - One of the best experts on this subject based on the ideXlab platform.
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multiferroic bismuth ferrite perturbed angular correlation studies on its ferroic α β Phase transition
Physical Review B, 2020Co-Authors: G Marschick, Juliana Schell, Bernhard Stoger, Joao Goncalves, Maksim O Karabasov, D Zyabkin, A Welker, D GartnerAbstract:Work of numerous research groups has shown different outcomes of studies of the transition from the ferroelectric $\ensuremath{\alpha}$-Phase to the high temperature $\ensuremath{\Beta}$-Phase of the multiferroic, magnetoelectric perovskite Bismuth Ferrite (${\mathrm{BiFeO}}_{3}$ or BFO). Using the perturbed angular correlation (PAC) method with $^{111m}\mathrm{Cd}$ as the probe nucleus, the $\ensuremath{\alpha}$ to $\ensuremath{\Beta}$ Phase transition was characterized. The Phase transition temperature, the change of the crystal structure, and its parameters were supervised with measurements at different temperatures using a six detector PAC setup to observe the $\ensuremath{\gamma}\ensuremath{-}\ensuremath{\gamma}$ decay of the $^{111m}\mathrm{Cd}$ probe nucleus. The temperature dependence of the hyperfine parameters shows a change in coordination of the probe ion, which substitutes for the bismuth site, forecasting the Phase transition to $\ensuremath{\Beta}$-BFO by either increasing disorder or formation of a polytype transition structure. A visible drop of the quadrupole frequency ${\ensuremath{\omega}}_{0}$ at a temperature of about ${T}_{c}\ensuremath{\approx}{820}^{\ensuremath{\circ}}\phantom{\rule{0.16em}{0ex}}\mathrm{C}$ indicates the $\ensuremath{\alpha}\ensuremath{-}\ensuremath{\Beta}$ Phase transition. For a given crystal symmetry, the DFT-calculations yield a specific local symmetry and electric field gradient value of the probe ion. The $Pbnm$ ($\ensuremath{\Beta}$-BFO) crystal symmetry yields calculated local electric field gradients, which very well match our experimental results. The assumption of other crystal symmetries results in significantly different computed local environments not corresponding to the experiment.