The effect of oxygen vacancy on the oxide ion mobility in LaAlO3-based oxides

Nguyen, Tuong Lan

doi:10.1016/s0167-2738(00)00640-8

Cited by 120 publications

(61 citation statements)

References 11 publications

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“…When the substituting cation has lower oxidation state, anionic vacancies or unusually high oxidation states of B cation are generated to maintain the structure electroneutrality. The electrical properties of La-and/or Al-site substituted LaAlO 3 compounds have been the subject of several studies (2)(3)(4)(5). The catalytic properties of La 1-x M x Al O 3-δ (A = Na, K, Ca, Sr, Ba, x= 0.1) oxides have been studied towards methane coupling reaction (6).…”

Section: Introductionmentioning

confidence: 99%

Synthesis and properties of La1-x Cax Al O3

Diafi¹,

Omari²

2012

Bol. Soc. Esp. Ceram. Vidr.

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La 1 -x Ca x Al O 3 (0 ≤ x ≤ 0.6) perovskite-type oxides were prepared by co-precipitation method using metal nitrate salts as cation precursors and NaOH solution as the precipitating agent. Differential thermal analysis (DTA) and thermogravimetric analysis (TGA) results indicate that decomposition of the precursor to the oxide begins at ~ 800°C. Powder X-ray diffraction (XRD) patterns confirm the formation of the perovskite phase. Both undoped and doped lanthanum aluminates show two IR active vibrational modes at 450 and 670 cm −1 which are assigned to AlO 6 octahedra of the oxide matrix. The microstructure and morphology of the compounds show that the particles are nearly spherical in shape and are agglomerated. Electrochemical measurements indicate that the catalytic activity is strongly influenced by lanthanum doping. The highest electrode performance is achieved with large calcium content. Keywords: perovskite oxide, chemical co-precipitation, powder diffraction, electrochemical properties Síntesis y propiedades de La 1-x Ca x Al O 3Se prepararon diferentes óxidos tipo perovskita con formulación La 1 -x Ca x Al O 3 (0 ≤ x ≤ 0.6) mediante método de coprecipitación empleando sales nitrato como precursores catiónicos y NaOH como agente precipitante. Los resultados de análisis térmico diferencial (DTA) y análisis termogravimétrico (TGA) indican que la descomposición del precursor del óxido comienza a ~ 800°C. Los patrones de difracción de rayos-X de polvo (XRD) confirman la formación de la fase perovskita. Los aluminatos de lantano, tanto dopado como no dopado, muestran dos modos vibracionales activos a 450 y 670 cm -1 que se asignan a octahedros AlO 6 de la matriz del óxido. La microestructura y morfología de los compuestos muestran que las partículas son de forma próxima a la esférica y aparecen en forma de aglomerados. Las medidas electroquímicas indican que actividad catalítica se ven fuertemente influenciadas por el dopaje con lantano. La mayor actividad del electrodo se alcanza con altos contenidos de calcio.Palabras clave: óxido perovskítico, coprecipitación química, difracción de polvo, propiedades electroquímicas.

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Section: Introductionmentioning

confidence: 99%

Synthesis and properties of La1-x Cax Al O3

Diafi¹,

Omari²

2012

Bol. Soc. Esp. Ceram. Vidr.

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“…1͑b͔͒ can likewise be ascribed to hole conduction following a ͑+1 / 4͒-dependence in the oxidizing regime and a constant ionic conductivity contribution under reducing atmospheres. 13 The mixed ionic electronic conduction characteristic of the two materials allows that an equilibrium of the entire oxygen sublattice of the LAO/STO-heterostructure with the surrounding atmosphere was established in the studied temperature range. In particular, the epitaxial LAO layer does not work as a barrier for oxygen diffusion above 800 K.…”

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confidence: 99%

High temperature conductance characteristics of LaAlO3/SrTiO3-heterostructures under equilibrium oxygen atmospheres

Gunkel¹,

Hoffmann‐Eifert²,

Dittmann³

et al. 2010

Applied Physics Letters

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The interface conductance of LaAlO3/SrTiO3 heterostructures was investigated under high temperature oxygen equilibrium. The dependence of the heterostructure’s conductance on oxygen partial pressure (from 10−22 to 1 bar) and temperature (800 to 1100 K) was compared to the characteristic of SrTiO3 single crystals, which is described in terms of a defect chemistry model. Up to 950 K the equilibrated heterostructures reveal an additional influence of a metallic-like conduction path with a very slight dependence on the oxygen partial pressure. Donor-type interface states which may result from either lattice distortions or A-site cation intermixing during processing are discussed as a possible origin for the exceptional interface conduction of LaAlO3/SrTiO3 heterostructures.

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“…nature of the B site cation, whereas the ion and/or elec tronic conductivity can be changed by controlling the selection and composition of A site cation. The sub stitution of Sr 2＋ for La 3＋ in LaAlO3 creates larger numbers of oxygen vacancies and the ionic conductivity of La0.8Sr0.2AlO3-δ (x＝0.05-0.2) is higher than that of 15) LaAlO3 .…”

Section: Resultsmentioning

confidence: 98%

Steam Reforming of Ethanol over Co/La1-xSrxBO3 (B = Al, Cr, Mn, Fe) Catalysts

浩平

佳恵

泰

et al. 2008

J. Jpn. Petrol. Inst.

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The steam reforming of ethanol for producing hydrogen was evaluated over 5 wt％ Co catalysts supported on perovskite-type oxides, Cr, Mn, Fe,2) at 823 K with a molar H2O/C2H5OH ratio of 6. Co/LaAlO3 showed higher catalytic activity and stability than Co catalysts supported on LaCrO3, LaFeO3 and LaMnO3. The molar La/Al ratio markedly affected the stability of Co/LaAlO3 catalyst and a molar La/Al ratio of 1 was the most suitable, suggesting that the properties of the perovskite structure are important in the catalytic activity and stability. Partial substitution of Sr 2＋ for La 3＋ in LaAlO3 resulted in further remarkable improvement of catalytic activity and hydrogen yield. We consider that enhanced mobility of lattice oxygen in La1-xSrxAlO3-δ allows more frequent participation in the oxidation of intermediates over metallic cobalt, leading to both high catalytic activity and stability of Co/La1-xSrxAlO3-δ in comparison with Co/LaAlO3.

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The effect of oxygen vacancy on the oxide ion mobility in LaAlO3-based oxides

Cited by 120 publications

References 11 publications

Synthesis and properties of La<sub>1-x</sub> Ca<sub>x</sub> Al O<sub>3</sub>

Synthesis and properties of La<sub>1-x</sub> Ca<sub>x</sub> Al O<sub>3</sub>

High temperature conductance characteristics of LaAlO3/SrTiO3-heterostructures under equilibrium oxygen atmospheres

Steam Reforming of Ethanol over Co/La<sub>1-<i>x</i></sub>Sr<sub><i>x</i></sub>BO<sub>3</sub> (B = Al, Cr, Mn, Fe) Catalysts

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