The Effect of Ion Size on Solution Mechanism and Defect Cluster Geometry

Grimes, Robin W.; Busker, Gerdjan; McCoy, M. A.; Chroneos, Alexander; Kilner, John A.; Chen, Shaoping

doi:10.1002/bbpc.199700026

Cited by 64 publications

(47 citation statements)

References 26 publications

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“…The efficacy of the parameters used has been established for Pr 2 NiO 4 as the calculated unit cell volume is within 0.74% of the determined value (maximum percent difference of the lattice parameters is 1.75%), 5 whereas the oxygen-oxygen interaction has been successfully used in a number of oxides. [10][11][12] Initial configurations for a given stoichiometry were created from a 10 Â 10 Â 4 supercell of the experimentally determined structure of Pr 2 NiO 4+d . Additional oxygen ions were assigned at a random sample of interstitial sites within the crystal, the This journal is c the Owner Societies 2010 PAPER www.rsc.org/pccp | Physical Chemistry Chemical Physics total number of ions in the simulations were therefore 5600 + 800d for a particular stoichiometry.…”

Section: Methodsmentioning

confidence: 99%

Molecular dynamics study of oxygen diffusion in Pr2NiO4+δ

Parfitt

Chroneos

Kilner

et al. 2010

Phys. Chem. Chem. Phys.

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101

116

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Oxygen transport in tetragonal Pr 2 NiO 4+d has been investigated using molecular dynamics simulations in conjunction with a set of Born model potentials. Oxygen diffusion in Pr 2 NiO 4+d is highly anisotropic, occurring almost entirely via an interstitialcy mechanism in the a-b plane. The calculated oxygen diffusivity has a weak dependence upon the concentration of oxygen interstitials, in agreement with experimental observations. In the temperature range 800-1500 K, the activation energy for migration varied between 0.49 and 0.64 eV depending upon the degree of hyperstoichiometry. The present results are compared to previous work on oxygen self-diffusion in related K 2 NiF 4 structure materials.

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Section: Methodsmentioning

confidence: 99%

Molecular dynamics study of oxygen diffusion in Pr2NiO4+δ

Parfitt

Chroneos

Kilner

et al. 2010

Phys. Chem. Chem. Phys.

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101

116

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“…the energy barriers for diffusion) [16][17][18][19]. Controlling point defects such as vacancies is important for semiconductors, superconductors, and oxides [20][21][22][23][24][25][26][27][28]. A way to defect engineer the concentration and clustering of point defects in the anion sublattice (for example oxygen vacancies) is via the introduction of dopants.…”

mentioning

confidence: 99%

Defect processes in Li2ZrO3: insights from atomistic modelling

Kordatos

Christopoulos

Kelaidis

et al. 2017

J Mater Sci: Mater Electron

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density functional theory (DFT) simulations in conjunction with experimental nuclear magnetic resonance (NMR) in order to investigate the Li ion migration mechanisms. Disorder in the anion sublattice can impact the material properties and the diffusion of point defects [14,15]. This is a common future in energy related materials where intrinsic disorder and doping can influence the formation (i.e. concentration of point defects mediating diffusion) and the migration (i.e. the energy barriers for diffusion) [16][17][18][19]. Controlling point defects such as vacancies is important for semiconductors, superconductors, and oxides [20][21][22][23][24][25][26][27][28]. A way to defect engineer the concentration and clustering of point defects in the anion sublattice (for example oxygen vacancies) is via the introduction of dopants. This is effectively to maintain charge balance in the lattice [29]. For example the introduction of two trivalent dopants in the tetravalent cerium site in CeO 2 can be charge balanced by the formation of an oxygen vacancy. Therefore the introduction of trivalent dopants in CeO 2 is an efficient way to form oxygen vacancies at concentrations higher than the equilibrium concentration [29].Atomistic simulation is an efficient and powerful way to understand the energetics of point defects in energy materials [30][31][32]. The main aim of the present study is to systematically investigate the intrinsic defect processes and impact of doping in Li 2 ZrO 3 using DFT. In particular, we consider here divalent (Mg, Zn, Ca, Cd, Sr, Ba), trivalent (Al, Ga, Sc, In, Y) and tetravalent (Si, Ge, Ti, Sn, Pb, Ce) substitutionals and their association with oxygen vacancies.Abstract Lithium zirconate (Li 2 ZrO 3 ) is an important material that is considered as an anode in lithium-ion batteries and as a nuclear reactor breeder material. The intrinsic defect processes and doping can impact its material properties. In the present study we employ density functional theory calculations to calculate the defect processes and doping in Li 2 ZrO 3 . Here we show that the lithium Frenkel is the dominant intrinsic defect process and that dopants substituting in the zirconium site strongly associate with oxygen vacancies. In particular, it is calculated that divalent dopants more strongly bind with oxygen vacancies, with trivalent dopants following in binding energies and even tetravalent dopands having significant binding energies. The results are discussed in view of the application of Li 2 ZrO 3 in energy applications.

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“…The convergence criteria for geometry optimization are: the difference in total energy per atom within 5 9 10 -6 eV, the ionic Hellmann-Feynman forces within 0.01 eV/Å , maximum stress within 0.02 GPa, and the maximum ionic displacement within 5 9 10 -4 Å . The effectiveness of atomistic simulations to explain defect processes has been discussed in early studies [41][42][43][44][45][46][47][48]. Table 1.…”

Section: Methodsmentioning

confidence: 99%

Structural and optical properties of the recently synthesized (Zr3−x Ti x )AlC2 MAX phases

Hadi

Panayiotatos

Chroneos

2016

J Mater Sci: Mater Electron

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In the present study we investigate the structural, Fermi surface and optical properties of the recently synthesized (Zr 3-x Ti x )AlC 2 MAX phases using density functional theory. The inclusion of Ti in the M site causes a reduction of both the a and c lattice parameters. The reduction of the a lattice parameter with respect to Ti content is more significant and this is reflected in the increase of the c/a ratio. The Fermi surfaces are formed mainly due to the low-dispersive transition metal d-like orbitals, which are responsible for the conductivity in the compounds. The energy loss spectra reveals that the two end members of (Zr 3-x Ti x )AlC 2 (x = 0 and 3) change from metallic to dielectric response at incident light energies 11.9, 13.4 and 10.8, 13.5 eV for [100] and [001] polarization directions, respectively. The reflectivity spectra indicate the ability of two end compounds Zr 3 AlC 2 and Ti 3 AlC 2 to be candidate materials for coatings to reduce solar heating. The calculated optical functions show the dependence on the polarization directions.

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The Effect of Ion Size on Solution Mechanism and Defect Cluster Geometry

Cited by 64 publications

References 26 publications

Molecular dynamics study of oxygen diffusion in Pr2NiO4+δ

Molecular dynamics study of oxygen diffusion in Pr2NiO4+δ

Defect processes in Li2ZrO3: insights from atomistic modelling

Structural and optical properties of the recently synthesized (Zr3−x Ti x )AlC2 MAX phases

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