Incorporation and migration of hydrogen in yttria-stabilized cubic zirconia: Insights from semilocal and hybrid-functional calculations

Marinopoulos, A. G.

doi:10.1103/physrevb.86.155144

Cited by 24 publications

(54 citation statements)

References 74 publications

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“…In the present study a percentage of 25% was chosen for exact exchange when employing the HSE06 functional. This led to an energy gap equal to 5.37 eV, a value consistent with existing experimental reports of stabilized cubic zirconia and results of other firstprinciples calculations of yttria-stabilized zirconia of similar yttria content [31,52].…”

Section: A Theorysupporting

confidence: 89%

“…The ensuing energy minimization led to final minimum-energy configurations which entailed important structural distortions with respect to the starting (ideal) fluorite cells. The anion sublattice exhibited the larger distortions with some of the oxygen ions displacing as far as 0.8Å away from their ideal fluorite sites, in accordance with previous theoretical studies of cubic stabilized zirconia with similar content of stabilizing oxides [31,52]. The lowestenergy supercell was structurally similar to the one determined for yttria-stabilized zirconia in our previous work [31] and was subsequently used for the defect calculations.…”

Section: A Theorysupporting

confidence: 86%

“…More specifically, DFT-based calculations determined the type of hydrogen configurations and defect electrical levels for hydrogen in the monoclinic [26,27], the ideal cubic [28,29] and tetragonal [30], and the cubic yttria-stabilized [31] phases. For bulk crystalline YSZ [31], in particular, the calculations showed that hydrogen is an amphoteric impurity and a negative-U defect with the pinning level, E(−/+), lying deep inside the gap. Hydrogen behaved similarly in the pure monoclinic phase both in zirconia [27] and in the isovalent and isostructural hafnia [27,32], with both studies employing hybrid-functional approaches.…”

Section: Introductionmentioning

confidence: 99%

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Isolated hydrogen configurations in zirconia as seen by muon spin spectroscopy andab initiocalculations

et al. 2016

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We present a systematic study of isolated hydrogen in diverse forms of ZrO 2 (zirconia), both undoped and stabilized in the cubic phase by additions of transition-metal oxides (Y 2 O 3 , Sc 2 O 3 , MgO, CaO). Hydrogen is modeled by using muonium as a pseudoisotope in muon-spin spectroscopy experiments. The muon study is also supplemented with first-principles calculations of the hydrogen states in scandia-stabilized zirconia by conventional density-functional theory (DFT) as well as a hybrid-functional approach which admixes a portion of exact exchange to the semilocal DFT exchange. The experimentally observable metastable states accessible by means of the muon implantation allowed us to probe two distinct hydrogen configurations predicted theoretically: an oxygen-bound configuration and a quasiatomic interstitial one with a large isotropic hyperfine constant. The neutral-oxygen-bound configuration is characterized by an electron spreading over the neighboring zirconium cations, forming a polaronic state with a vanishingly small hyperfine interaction at the muon. The atom-like interstitial muonium is observed also in all samples but with different fractions. The hyperfine interaction is isotropic in calcia-doped zirconia [A iso = 3.02(8) GHz], but slightly anisotropic in the nanograin yttria-doped zirconia [A iso = 2.1(1) GHz, D = 0.13(2) GHz] probably due to muons stopping close to the interface regions between the nanograins in the latter case.

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Section: A Theorysupporting

confidence: 89%

Section: A Theorysupporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

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Isolated hydrogen configurations in zirconia as seen by muon spin spectroscopy andab initiocalculations

et al. 2016

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“…It is usually assumed that information obtained from μSR can be transferred with appropriate modifications to H. However, overlapping experiments to support this assumption are scarce. A particularly relevant case is the doping character of H in semiconductors and oxides [3][4][5][6], where practically all calculations refer to the electronic structure of H whereas most experimental information comes from μSR [7][8][9][10][11][12][13]. Overlapping data exist only for ZnO where proton-ENDOR (electron-nuclear double resonance) data [14] can be compared directly with μSR results [15][16][17][18].…”

mentioning

confidence: 99%

Muonium donor in rutileTiO2and comparison with hydrogen

et al. 2015

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Muonium, a positive muon and an electron, is often used as an experimentally accessible substitute for hydrogen in materials research. In semiconductors and insulators, a large amount of information on the hydrogen behavior is deduced from this analogy; however, it is seldom demonstrated that this procedure is justified. We show here, via a comparison of the hyperfine interactions, that in TiO 2 muonium and hydrogen form the same configuration with the same basic electronic structure. A detailed description of the bonding characteristics of the muon to the Ti 3+ polaron is presented. The special role of muon motion within the so-called oxygen channel in the rutile structure, which occurs at a lower temperature than for hydrogen, is emphasized. Muonium (Mu) is a pseudoisotope of hydrogen in which the proton is replaced by a positive muon (μ + ), with a factor of 9 lighter mass. Muon spin spectroscopy (μSR) uses muons implanted with 100% spin polarization and offers a very sensitive method to study the properties of this isolated pseudohydrogen in solids [1,2]. It is usually assumed that information obtained from μSR can be transferred with appropriate modifications to H. However, overlapping experiments to support this assumption are scarce. A particularly relevant case is the doping character of H in semiconductors and oxides [3][4][5][6], where practically all calculations refer to the electronic structure of H whereas most experimental information comes from μSR [7][8][9][10][11][12][13]. Overlapping data exist only for ZnO where proton-ENDOR (electron-nuclear double resonance) data [14] can be compared directly with μSR results [15][16][17][18]. A number of properties (e.g., ionization energy) are indeed similar for the two species. However, the measured hyperfine interaction (hfi), scaled with the magnetic moments, differs by almost a factor of 10. This raised the question of whether the same configuration is measured, or if the H center may involve an additional defect [19,20].Here, we report a case where the same configuration can be established for H and Mu. We compare the hfi of the μSR experiment with the proton-ENDOR result, both for rutile TiO 2 . The H center in TiO 2 was extensively studied by Brant et al.[21] using electron paramagnetic resonance (EPR) and ENDOR, who found that the electron is located at the Ti ion reducing it from Ti 4+ to Ti 3+ . H is bound to one of the six O atoms surrounding Ti and the magnetic interaction between the proton and the electron is mainly dipolar. This specific hfi permits a sensitive comparison of the two experiments. We have observed a dramatic change of the μSR spectra with increasing temperature and a complete disappearance of the hyperfine splitting at 10 K. We show that this is due to rapid jumps of the muon between neighboring bonding positions to O atoms around Ti 3+ . The very strong angle dependence of the dipolar interaction and the averaging over values in different * ruivilao@fis.uc.pt positions lead to the reduction and final disappearance of the hfi...

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“…It acts as a donor (H + ) in a p-type material and as an acceptor (H − ) in an n-type material, always counteracting the prevailing conductivity [174]. This depends on whether the transition level, ε(+/−), intersects the CB or is deep in the energy gap, and H 0 , is never thermodynamically stable [174,178]. Defect-related H effects in semiconductors have been investigated for materials such as Si, Ge, GaAs, and GaP, and this has been extensively reviewed elsewhere [170,174,[179][180][181].…”

Section: Hydrogen Co-doping Effectsmentioning

confidence: 99%

A brief review of co-doping

et al. 2016

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Dopants and defects are important in semiconductor and magnetic devices. Strategies for controlling doping and defects have been the focus of semiconductor physics research during the past decades and remain critical even today. Co-doping is a promising strategy that can be used for effectively tuning the dopant populations, electronic properties, and magnetic properties. It can enhance the solubility of dopants and improve the stability of desired defects. During the past 20 years, significant experimental and theoretical efforts have been devoted to studying the characteristics of co-doping. In this article, we first review the historical development of co-doping. Then, we review a variety of research performed on co-doping, based on the compensating nature of co-dopants. Finally, we review the effects of contamination and surfactants that can explain the general mechanisms of co-doping.

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Incorporation and migration of hydrogen in yttria-stabilized cubic zirconia: Insights from semilocal and hybrid-functional calculations

Cited by 24 publications

References 74 publications

Isolated hydrogen configurations in zirconia as seen by muon spin spectroscopy andab initiocalculations

Isolated hydrogen configurations in zirconia as seen by muon spin spectroscopy andab initiocalculations

Muonium donor in rutileTiO2and comparison with hydrogen

A brief review of co-doping

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