Uncovering the Thermo-Kinetic Origins of Phase Ordering in Mixed-Valence Antimony Tetroxide by First-Principles Modeling

2017 ◽  
Vol 56 (11) ◽  
pp. 6545-6550
Author(s):  
Chang-Eun Kim ◽  
Su-Hyun Yoo ◽  
David F. Bahr ◽  
Catherine Stampfl ◽  
Aloysius Soon
Keyword(s):  
First Principles ◽  
Mixed Valence ◽  
Phase Ordering ◽  
Antimony Tetroxide

scholarly journals Correction: Effects of mixed-valence states of Eu-doped FAPbI3 perovskite crystals studied by first-principles calculation

2021 ◽  
Vol 2 (8) ◽  
pp. 2759-2759
Author(s):  
Atsushi Suzuki ◽  
Takeo Oku
Keyword(s):  
First Principles ◽  
Mixed Valence ◽  
First Principles Calculation ◽  
Valence States

Correction for ‘Effects of mixed-valence states of Eu-doped FAPbI3 perovskite crystals studied by first-principles calculation’ by Atsushi Suzuki et al., Mater. Adv., 2021, DOI: 10.1039/D0MA00994F.

Stability of Ordered B2-βO and Disordered BCC-β Phases in Tial - A First Principles Study

2021 ◽  
Vol 1016 ◽  
pp. 1159-1165
Author(s):  
Florian Pyczak ◽  
Victoria Kononikhina ◽  
Andreas Stark
Keyword(s):  
First Principles ◽  
Density Functional ◽  
High Energy ◽  
First Principles Calculations ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
Tial Alloys ◽  
Β Phase ◽  
Phase Ordering ◽  
Strength And Ductility

Either at higher temperatures or when a certain alloying element content is exceeded, γ-TiAl alloys contain the β phase (bcc) or its ordered derivate βo (B2). The relatively soft β phase can facilitate hot deformation, but βo is detrimental for creep strength and ductility. Thus, knowledge about βo→β phase transformation is desirable. Surprisingly, even for the binary Ti-Al system it is under discussion whether the ordered βo phase exists. Also, the effect of alloying elements on the β phase ordering is still unclear. In the present work the ordering of the β phase in binary Ti-(39,42,45)Al and ternary Ti-42Al-2X alloys (X=Fe, Cr, Nb, Ta, Mo) which was experimentally investigated by neutron and high energy X-ray diffraction is compared with the results of first principles calculations using density functional theory. Except for Cr the experimentally determined and the predicted behavior correspond.

Effect of Replacement of Fe2+ by Co2+ in W-Type Hexagonal Ferrite BaFe18O27 to its Electronic Properties from First Principles

2012 ◽  
Vol 424-425 ◽  
pp. 137-140
Author(s):  
Chung Ho Ri ◽  
Lin Li ◽  
Yang Qi ◽  
Su Nam Kim
Keyword(s):  
First Principles ◽  
Carrier Density ◽  
Mixed Valence ◽  
Charge Carrier Density ◽  
Generalized Gradient ◽  
Ground Structure ◽  
Generalized Gradient Approximation ◽  
Valence States ◽  
Hubbard U ◽  
Electronic Ground

Using a model in which Fe at 6g sites is assumed to be partially replaced by Co, the electronic ground structure of BaCo2Fe16O27and the origin of the electrical conductivity have been studied within framework of the generalized gradient approximation (GGA) plus Hubbard U (GGA+U) calculation. Replacement of Fe at 6g site of BaFe18O27by Co causes the mixed valence states of Fe cations at 6g sites to vanish and the charge carrier density to lower. This is the main reason why both of materials reveal high electrical conductive anisotropy and the electrical resistivity of BaCo2-W is 103~104times higher than BaFe2-W.

scholarly journals Towards a First-Principles Evaluation of Transport Mechanisms in Molecular Wires

2020 ◽  
Author(s):  
Susanne kröncke ◽  
Carmen Herrmann
Keyword(s):  
Charge Transport ◽  
First Principles ◽  
Density Functional ◽  
Mixed Valence ◽  
Maximum Error ◽  
Molecular Wires ◽  
Polarizable Continuum Model ◽  
Charge Delocalization ◽  
Nanoscale Electronics ◽  
Transition Length

Understanding charge transport through molecular wires is important for nanoscale electronics and biochemistry. Our goal is to establish a simple first-principles protocol for predicting the charge transport mechanism in such wires, in particular the crossover from coherent tunneling for short wires to incoherent hopping for longer wires. This protocol is based on a combination of density-functional theory with a polarizable continuum model introduced by Kaupp et al. for mixed-valence molecules, which we had previously found to work well for length-dependent charge delocalization in such systems. We combine this protocol with a new charge delocalization measure tailored for molecular wires, and we show that it can predict the tunneling-to hopping transition length with a maximum error of one subunit in five sets of molecular wires studied experimentally in molecular junctions at room temperature. This suggests that the protocol is also well suited for estimating the extent of hopping sites as relevant, e.g., for the intermediate tunneling-hopping regime in DNA.

scholarly journals Towards a First-Principles Evaluation of Transport Mechanisms in Molecular Wires

2020 ◽  
Author(s):  
Susanne kröncke ◽  
Carmen Herrmann
Keyword(s):  
Charge Transport ◽  
First Principles ◽  
Density Functional ◽  
Mixed Valence ◽  
Maximum Error ◽  
Molecular Wires ◽  
Polarizable Continuum Model ◽  
Charge Delocalization ◽  
Nanoscale Electronics ◽  
Transition Length

Understanding charge transport through molecular wires is important for nanoscale electronics and biochemistry. Our goal is to establish a simple first-principles protocol for predicting the charge transport mechanism in such wires, in particular the crossover from coherent tunneling for short wires to incoherent hopping for longer wires. This protocol is based on a combination of density-functional theory with a polarizable continuum model introduced by Kaupp et al. for mixed-valence molecules, which we had previously found to work well for length-dependent charge delocalization in such systems. We combine this protocol with a new charge delocalization measure tailored for molecular wires, and we show that it can predict the tunneling-to hopping transition length with a maximum error of one subunit in five sets of molecular wires studied experimentally in molecular junctions at room temperature. This suggests that the protocol is also well suited for estimating the extent of hopping sites as relevant, e.g., for the intermediate tunneling-hopping regime in DNA.

scholarly journals Effects of mixed-valence states of Eu-doped FAPbI3 perovskite crystals studied by first-principles calculation

2021 ◽  
Vol 2 (8) ◽  
pp. 2609-2616
Author(s):  
Atsushi Suzuki ◽  
Takeo Oku
Keyword(s):  
First Principles ◽  
Electronic Structures ◽  
Mixed Valence ◽  
First Principles Calculation ◽  
Valence States

Effects of mixed-valence states of europium (Eu)-incorporated CH(NH2)2PbI3 (FAPbI3) and CH3NH3PbI3 (MAPbI3) perovskite crystals on electronic structures were investigated by first-principles calculation.

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