Defect complexes in Li-doped MgO

Richter, Norina A.; Stavale, Fernando; Levchenko, Sergey V.; Nilius, Niklas; Freund, Hans‐Joachim; Scheffler, Matthias

doi:10.1103/physrevb.91.195305

Cited by 24 publications

(30 citation statements)

References 33 publications

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“…Using HSE geometries for two smallest unit cells considered results in negligible changes in the calculated formation energies. Vibrational energy ÁF q vib ðTÞ and van der Waals contributions to the formation energies were analyzed as well [20], but found to be insignificant for this study.…”

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confidence: 94%

Concentration of Vacancies at Metal-Oxide Surfaces: Case Study of MgO(100)

et al. 2013

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We investigate the effects of doping on the formation energy and concentration of oxygen vacancies at a metal-oxide surface, using MgO(100) as an example. Our approach employs density-functional theory, where the performance of the exchange-correlation functional is carefully analyzed, and the functional is chosen according to a condition on density-functional theory ionization energies. The approach is further validated by coupled-cluster calculations, including single, double, and perturbative triple substitutions, for embedded clusters. We demonstrate that the concentration of oxygen vacancies at a doped oxide surface is largely determined by the formation of a macroscopically extended space-charge region.

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confidence: 94%

Concentration of Vacancies at Metal-Oxide Surfaces: Case Study of MgO(100)

et al. 2013

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“…Challenging examples are the so-called polaron states, where electrons or holes are trapped by significant lattice polarization, either in a perfect crystal [5,6] or at pre-existing defects [7,8]. Polarons play crucial roles in various material properties, e.g., conductivity [5,9], chemical reactivity [10], and optical absorption and emission [11,12]. In the context of polarons, the energy difference between the conduction (valence) band and the CTL of an electron (hole) polaron defect is the trapping energy of the polaron.…”

Section: Introductionmentioning

confidence: 99%

Role of long-range exact exchange in polaron charge transition levels: The case of MgO

Wing

Strand

Durrant

et al. 2020

Phys. Rev. Materials

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Predicting the degree of localization and calculating the trapping energies of polarons in insulators by density functional theory (DFT) is challenging. Hybrid functionals are often reparametrized to obtain accurate results and the a priori selection of these parameters is still an open question. Here we test the accuracy of several range-separated hybrid functionals, all reparametrized to produce an accurate band gap, by calculating the charge transition levels (CTLs) of experimentally well-studied hole polaron defect centers in MgO. We show that the functional with screened long-range exact exchange is moderately but consistently more accurate than functionals which do not include long-range exact exchange. We provide evidence that the source of the improved accuracy is the eigenvalue associated with the valence band maximum of the bulk material. We discuss the extent to which this accuracy relates to Koopmans' compliance of the defect energy level.

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“…Such thin films are amenable to characterization by e.g. low-energy electron diffraction and scanning tunneling microscopy [15], and studies utilizing them have yielded important insights into the surface properties of MgO and how these are influenced by dopants [16][17][18][19][20].…”

Section: Introductionmentioning

confidence: 99%

Redox behavior of iron at the surface of an O(100) single crystal studied by ambient-pressure photoelectron spectroscopy

Merte

Gustafson

Shipilin

et al. 2017

Catalysis, Structure & Reactivity

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We have studied the oxidation and reduction of iron in an Fe-doped MgO single crystal by O 2 , H 2 and CO 2 using ambient-pressure XPS and NEXAFS. Surface charging of the crystal was rendered manageable by the elevated temperatures and the gas atmospheres. The oxidation state of iron was found to shift reversibly between the Fe 2+ and Fe 3+ states, with a strong asymmetry in the rates; while oxidation by O 2 or CO 2 was nearly complete at 100 • C, reduction by H 2 began at ∼ 300 • C, and was still incomplete at 600 • C. Grazing-incidence XRD characterization of the crystal indicated the presence of octahedral, nanoscale inclusions assigned to the magnesioferrite spinel (MgFe 2 O 4 ). It is proposed that the redox behavior observed involves interconversion between the rock-salt (Fe x Mg 1−x O) and spinel phases, with the more open lattice containing Fe 3+ enabling more rapid ion diffusion and thus more facile oxidation compared to reduction. ARTICLE HISTORY

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Defect complexes in Li-doped MgO

Cited by 24 publications

References 33 publications

Concentration of Vacancies at Metal-Oxide Surfaces: Case Study of MgO(100)

Concentration of Vacancies at Metal-Oxide Surfaces: Case Study of MgO(100)

Role of long-range exact exchange in polaron charge transition levels: The case of MgO

Redox behavior of iron at the surface of an O(100) single crystal studied by ambient-pressure photoelectron spectroscopy

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