High-pressure and high-temperature synthesis of a cubic IrO2 polymorph

Ono, Shigeaki; Kikegawa, Takumi; Ohishi, Yasuo

doi:10.1016/j.physb.2005.03.014

Cited by 18 publications

(23 citation statements)

References 24 publications

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“…72 Similar phase stability order for IrO 2 was also previously reported using PBE calculations, while PBEsol and AM05 functionals resulted in the pyrite phase being more stable than the columbite phase. 72 Similar phase stability order for IrO 2 was also previously reported using PBE calculations, while PBEsol and AM05 functionals resulted in the pyrite phase being more stable than the columbite phase.…”

Section: Bulk Propertiessupporting

confidence: 78%

“…For the high pressure pyrite phase, the value of a = 4.96 Å predicted GPa and is in good agreement with the experimental value of 306 GPa 72. For the high pressure pyrite phase, the value of a = 4.96 Å predicted GPa and is in good agreement with the experimental value of 306 GPa 72.…”

supporting

confidence: 80%

“…1b). 72 In addition to these experimental structures, we also consider hypothetical anatase (I4 1 /amd) (Fig. 1c), columbite (Pbcn) (Fig.…”

Section: Training Datamentioning

confidence: 99%

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Towards accurate prediction of catalytic activity in IrO₂ nanoclusters via first principles-based variable charge force field

et al. 2015

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IrO 2 is one of the most efficient electrocatalysts for the oxygen evolution reaction (OER), and also has other applications such as in pH sensors. Atomistic modeling of IrO 2 is critical for understanding the structure, chemistry, and nanoscale dynamics of IrO 2 in these applications. Such modeling has remained elusive due to the lack of an empirical force field (EFF) for IrO 2 . We introduce a first-principles-based EFF that couples the Morse (MS) potential with a variable charge equilibration method, QEq. The EFF parameters are optimized using a genetic algorithm (GA) on a density functional theory (DFT)-based training set. The resultant Morse plus QEq EFF, "MS-Q" in short, successfully reproduces the lattice constants, elastic constants, binding energies, and internal coordinates of various polymorphs of IrO 2 from DFT calculations. More importantly, it accurately captures key metrics for evaluating structural and chemical properties of catalysts such as surface energetics, equilibrium shape, electrostatic charges, oxygen vacancy formation energies, relative stability of low index rutile IrO 2 surfaces, and pressureinduced phase transformations. The MS-Q EFF is used to predict the oxygen binding energy (E ad ), a wellknown descriptor for OER activity, on various sites of a nanocatalyst. We find E ad to be more favorable at low coordination sites, i.e. edges and corners, compared to planar facets; E ad is also correlated with charge transfer between the adsorbed O and nanocrystal, highlighting the importance of variable charge electrostatics in modeling catalysis on metal oxide surfaces. Our variable charge force field offers encouraging prospects for carrying out large-scale reactive simulations to evaluate catalytic performance of IrO 2 surfaces and nanostructures. 4 interactions. 47-50 For example, a Morse+QEq (MS-Q) force field for titanium oxide, developed by Swamy and Gale, accurately predicted the bulk moduli and binding energies of various titanium oxide polymorphs, when compared to quantum mechanical calculations, but could not predict the relative surface stability in rutile TiO 2 . 48, 51 There are several possibilities for this shortcoming: the lack of surface energies in the training set, 51 the lack of parametrizing of QEq parameters, and/or the lack of adequate global parameter space search. We hypothesize that it is possible to successfully use MS-Q to describe the IrO 2 system by addressing these missing elements.Our approach for developing a MS-Q force-field incorporates several key elements: the inclusion of diverse local environments in an elaborate DFT training set that includes surfaces, the parameterization of QEq parameters, and the use of an evolutionary algorithm to parameterize MS-Q. The use of different local environments including broken bonds in the training set enhances the probability that chemical reactions can be modeled with the resultant force field. The QEq parameters, namely, electronegativity and chemical hardness, may depend on chemical environments and therefore should ...

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Section: Bulk Propertiessupporting

confidence: 78%

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confidence: 80%

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Towards accurate prediction of catalytic activity in IrO₂ nanoclusters via first principles-based variable charge force field

et al. 2015

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“…The stiffest rutile oxide is SiO2 and the softest one is PbO2, which is in agreement with the bonding analysis (see Figure 2) since SiO2 possesses the strongest bonds. The obtained elasticity values at 300 K are consistent with the available experimental data, deviating by 7.8% for TiO2 [65], 2.4% for CrO2 [2], 16.1% for MnO2 [66], 2.6% for NbO2 [67], 5.4% for OsO2 [68], 9.9% for IrO2 [69], 0.3% for PbO2 [70], and 7.9% for SiO2 [71]. This is acceptable based on the employed exchange-correlation functional, since deviations are commonly within 20% [72].…”

Section: Resultssupporting

confidence: 88%

“…The Y value slowly decreases with T, as expected, and the difference between the values for these binary oxides is constant. The stiffest rutile oxide is SiO 2 and the softest one is PbO 2 , which is in agreement with the bonding analysis (see Figure 2) [69], 0.3% for PbO 2 [70], and 7.9% for SiO 2 [71]. This is acceptable based on the employed exchange-correlation functional, since deviations are commonly within 20% [72].…”

Section: Resultssupporting

confidence: 88%

Intrinsic Thermal Shock Behavior of Common Rutile Oxides

Mušić

Stelzer

2019

Physics

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Rutile TiO2, VO2, CrO2, MnO2, NbO2, RuO2, RhO2, TaO2, OsO2, IrO2, SnO2, PbO2, SiO2, and GeO2 (space group P42/mnm) were explored for thermal shock resistance applications using density functional theory in conjunction with acoustic phonon models. Four relevant thermomechanical properties were calculated, namely thermal conductivity, Poisson’s ratio, the linear coefficient of thermal expansion, and elastic modulus. The thermal conductivity exhibited a parabolic relationship with the linear coefficient of thermal expansion and the extremes were delineated by SiO2 (the smallest linear coefficient of thermal expansion and the largest thermal conductivity) and PbO2 (vice versa). It is suggested that stronger bonding in SiO2 than PbO2 is responsible for such behavior. This also gave rise to the largest elastic modulus of SiO2 in this group of rutile oxides. Finally, the intrinsic thermal shock resistance was the largest for SiO2, exceeding some of the competitive phases such as Al2O3 and nanolaminated Ti3SiC2.

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Pressure-induced structural evolution of pyrite-type SiO2

et al. 2011

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High-pressure and high-temperature synthesis of a cubic IrO2 polymorph

Cited by 18 publications

References 24 publications

Towards accurate prediction of catalytic activity in IrO₂ nanoclusters via first principles-based variable charge force field

Towards accurate prediction of catalytic activity in IrO₂ nanoclusters via first principles-based variable charge force field

Intrinsic Thermal Shock Behavior of Common Rutile Oxides

Pressure-induced structural evolution of pyrite-type SiO2

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High-pressure and high-temperature synthesis of a cubic IrO2 polymorph

Cited by 18 publications

References 24 publications

Towards accurate prediction of catalytic activity in IrO2 nanoclusters via first principles-based variable charge force field

Towards accurate prediction of catalytic activity in IrO2 nanoclusters via first principles-based variable charge force field

Intrinsic Thermal Shock Behavior of Common Rutile Oxides

Pressure-induced structural evolution of pyrite-type SiO2

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Towards accurate prediction of catalytic activity in IrO₂ nanoclusters via first principles-based variable charge force field

Towards accurate prediction of catalytic activity in IrO₂ nanoclusters via first principles-based variable charge force field