In Situ Monitoring and Quantitative Analysis of Oxygen Diffusion Through Schottky-Barriers in SrTiO[sub 3] Bicrystals

Leonhardt, M.

doi:10.1149/1.1390827

Cited by 83 publications

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“…35 Since experiments on SrTiO 3 are performed at wide range of temperature and oxygen partial pressures, our defect concentrations are calculated as a function of temperature (100 K to 2000 K) and pressure (10 −20 atm to 10 15 atm). 8,[36][37][38][39] The formation energies are analyzed at representative temperatures of 0 K, 800 K and 1200 K.…”

Section: Methods Of Calculationmentioning

confidence: 99%

Method for defect stability diagram fromab initiocalculations: A case study of SrTiO3

2012

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Point defects play a dominant role in determining the wide spectrum of electronic and physical properties of semiconducting materials that have vast technological applications. Using ab-initio simulations, a method to calculate equilibrium defect concentrations, Fermi energy and defect stability diagrams as functions of external parameters, such as temperature and pressure, is presented. Using SrTiO3 as a representative material, we report our analysis of the stability of oxygen vacancies and interstitials, in their different charge states, as a function of temperature, oxygen partial pressure and Fermi energy of the system. Further, by analyzing the defect chemistry at experimentally relevant temperatures, we find that at low oxygen partial pressure, neutral oxygen vacancies are most dominant and at intermediate and high oxygen partial pressure, doubly charged oxygen vacancies defects are dominant.

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Section: Methods Of Calculationmentioning

confidence: 99%

Method for defect stability diagram fromab initiocalculations: A case study of SrTiO3

2012

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“…Polycrystalline perovskites have a wide range of applications, such as oxygen ion conductors in sensors, diverse electronic devices as varistors, 8,9 piezoelectric materials in actuators, dielectric materials in capacitors, and as substrate for thin film growth of high T c superconductors. 10 Examples where the macroscopic properties of these materials depend critically on the grain boundary structures and the intergranular films include increased toughness, [11][12][13] reduced ionic conductivity, 9,[14][15][16][17] diminished creep resistance, 18,19 tunable electrical conductivity, 20,21 decreased thermal conductivity, 22 and enhanced sintering behavior. 23 The reason for this dominance is that interfaces inherently contain a concentration of defects and dopants far in excess of the equilibrium distribution in the bulk of the material.…”

Section: Introductionmentioning

confidence: 99%

Graded interface models for more accurate determination of van der Waals–London dispersion interactions across grain boundaries

et al. 2006

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Attractive van der Waals-London dispersion interactions between two half crystals arise from local physical property gradients within the interface layer separating the crystals. Hamaker coefficients and London dispersion energies were quantitatively determined for Σ5 and near-Σ13 grain boundaries in SrTiO 3 by analysis of spatially resolved valence electron energy-loss spectroscopy (VEELS) data. From the experimental data, local complex dielectric functions were determined, from which optical properties can be locally analyzed. Both local electronic structures and optical properties revealed gradients within the grain boundary cores of both investigated interfaces. The results show that even in the presence of atomically structured grain boundary cores with widths of less than 1 nm, optical properties have to be represented with gradual changes across the grain boundary structures to quantitatively reproduce accurate van der Waals-London dispersion interactions. London dispersion energies of the order of 10% of the apparent interface energies of SrTiO 3 were observed, demonstrating their significance in the grain boundary formation process. The application of different models to represent optical property gradients shows that long-range van der Waals-London dispersion interactions scale significantly with local, i.e., atomic length scale property variations. Attractive van der Waals-London dispersion interactions between two half crystals arise from local physical property gradients within the interface layer separating the crystals. Hamaker coefficients and London dispersion energies were quantitatively determined for ⌺5 and near-͚13 grain boundaries in SrTiO 3 by analysis of spatially resolved valence electron energy-loss spectroscopy ͑VEELS͒ data. From the experimental data, local complex dielectric functions were determined, from which optical properties can be locally analyzed. Both local electronic structures and optical properties revealed gradients within the grain boundary cores of both investigated interfaces. The results show that even in the presence of atomically structured grain boundary cores with widths of less than 1 nm, optical properties have to be represented with gradual changes across the grain boundary structures to quantitatively reproduce accurate van der Waals-London dispersion interactions. London dispersion energies of the order of 10% of the apparent interface energies of SrTiO 3 were observed, demonstrating their significance in the grain boundary formation process. The application of different models to represent optical property gradients shows that long-range van der Waals-London dispersion interactions scale significantly with local, i.e., atomic length scale property variations. Disciplines Engineering | Materials Science and Engineering Comments

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“…Als Beispiel für den Transport über eine einzige wohldefinierte Korngrenze zeigt Abbildung 12 die Sauerstoffdiffusion in einen Fe-dotierten SrTiO 3 -Bikristall, der eine symmetrische Kippkorngrenze enthält. [18] Sauerstoff wird von rechts in die Probe eingebaut und bewegt sich schnell bis zur Korngrenze. Dann behindert die Korngrenze offensichtlich den weiteren Transport und führt zu einer ausgeprägten Stufe im Konzentrationsprofil.…”

Section: Schrittunclassified

“…Abbildung 12. Zeitliche Entwicklung der normalisierten Konzentrationsprofile entsprechend dem Experiment aus Abbildung 5 c; [18] Sauerstoff diffundiert von rechts ein. Einschub: Momentaufnahmen der Probe (Sauerstoff diffundiert von oben ein).…”

Section: Schrittunclassified

“…In letzter Zeit wurden einige wichtige Fortschritte bei bestimmten Aspekten des Gebiets erzielt, z. B.: 1) beim Verständnis elementarer Reaktionsschritte an der Gas-FeststoffGrenzfläche; [8][9][10][11][12] 2) bei der Verknüpfung der Geschwindigkeitskonstanten von Elementarreaktionen mit effektiven Parametern, wie sie in Relaxationsexperimenten gemessen werden; [13][14][15][16][17] 3) bei der Einbeziehung von Raumladungen in die Beschreibung der chemischen Diffusion; [18][19][20] 4) bei der Berücksichtigung der Kopplung von Diffusion und inneren Reaktionen; [21,22] 5) bei der Untersuchung komplexer und nichtlinearer Prozesse. [23][24][25][26][27][28][29][30][31][32][33] Auf experimenteller Seite hat die Entwicklung spezifischer In-situ-Methoden zu einem tiefgehenden Verständnis von Defektchemie und Transport beigetragen (siehe etwa Lit.…”

Section: Introductionunclassified

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Wie wird Sauerstoff in Oxide eingebaut? Kinetische Studie einer “simplen” Feststoffreaktion am Modellmaterial SrTiO₃

Merkle

Maier

2008

Angewandte Chemie

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Die Kinetik der Stöchiometrieänderung eines Oxids – zugleich Beispiel einer (nominell) einfachen Festkörperreaktion und Grundlage vieler technisch relevanter Vorgänge – wird untersucht und im Detail analysiert. Als Modellreaktion wurde der Sauerstoffeinbau in Strontiumtitanat gewählt. Der gesamte Prozess kann von der Oberflächenreaktion bis hin zum Volumentransport phänomenologisch und mechanistisch verstanden werden. Schlüssel hierzu sind ein genaues Verständnis der Defektchemie des Perowskits wie auch die Anwendung einer Vielzahl experimenteller und theoretischer Methoden, die zum Teil eigens im Rahmen dieser Untersuchung entwickelt wurden. Die Bedeutung von Reaktions‐ und Transportschritten für (elektro)chemische Anwendungen wird herausgestellt.

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In Situ Monitoring and Quantitative Analysis of Oxygen Diffusion Through Schottky-Barriers in SrTiO[sub 3] Bicrystals

Cited by 83 publications

References 0 publications

Method for defect stability diagram fromab initiocalculations: A case study of SrTiO3

Method for defect stability diagram fromab initiocalculations: A case study of SrTiO3

Graded interface models for more accurate determination of van der Waals–London dispersion interactions across grain boundaries

Wie wird Sauerstoff in Oxide eingebaut? Kinetische Studie einer “simplen” Feststoffreaktion am Modellmaterial SrTiO₃

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In Situ Monitoring and Quantitative Analysis of Oxygen Diffusion Through Schottky-Barriers in SrTiO[sub 3] Bicrystals

Cited by 83 publications

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Method for defect stability diagram fromab initiocalculations: A case study of SrTiO3

Method for defect stability diagram fromab initiocalculations: A case study of SrTiO3

Graded interface models for more accurate determination of van der Waals–London dispersion interactions across grain boundaries

Wie wird Sauerstoff in Oxide eingebaut? Kinetische Studie einer “simplen” Feststoffreaktion am Modellmaterial SrTiO3

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Wie wird Sauerstoff in Oxide eingebaut? Kinetische Studie einer “simplen” Feststoffreaktion am Modellmaterial SrTiO₃