Recent Progress in NOx Trap Technology

Brogan, Mark S.; Clark, Adam; Brisley, R. J.

doi:10.4271/980933

Cited by 41 publications

(7 citation statements)

References 5 publications

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“…The high temperature capabilities of langasite, for example, make it a prime candidate as a crystal microbalancebased sensor for in-situ monitoring of e.g., automobile exhaust [3][4][5]. This not only requires that langasite retain its piezoelectric properties to high temperatures, but that it also remain stable in atmospheres ranging from highly reducing to oxidizing.…”

Section: Introductionmentioning

confidence: 99%

Defects and transport in langasite I: Acceptor-doped (La3Ga5SiO14)

Seh

Tuller

2006

J Electroceram

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Both nominally undoped and 1%Sr-doped langasite were found to exhibit acceptor behavior and correspondingly mixed ionic-electronic conductivity under experimentally accessible conditions. At high pO 2 , the conductivity of nominally undoped langasite was pO 2 -independent (ionic behavior) but became increasingly pO 2 -dependent (n-type behavior) under reducing conditions. The substitution of strontium on lanthanum sites, increased the ionic and introduced a p-type electronic conductivity behavior at the highest pO 2 's, while completely depressing the n-type electronic conductivity -observations consistent with predictions of the proposed defect model based on oxygen vacancy formation in response to negatively charged acceptor impurities.Sr-doped langasite was found to have a higher activation energy for oxygen ion transport (1.27 ± 0.02 eV) than nominally undoped langasite (0.91 ± 0.01 eV). This difference could not be successfully explained by applying a simple defect association model but required the assumption of long range defect interactions. Using the defect model, a number of key equilibrium constants (reduction (5.7 ± 0.06 eV), oxidation (2.18 ± 0.08 eV), electron-hole generation (3.94 ± 0.07 eV), and defect mobilities (oxygen vacancies and holes) were derived and summarized.

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Section: Introductionmentioning

confidence: 99%

Defects and transport in langasite I: Acceptor-doped (La3Ga5SiO14)

Seh

Tuller

2006

J Electroceram

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“…The development and advancement of a catalysis technology depend on the synthesis and characterization of efficient catalytic materials, understanding of the reaction mechanism, and finally proper engineering of the catalytic system. There are a few reviews on NSR, where some aspects of either the overall mechanism or specific features such as sulfur poisoning or thermal deterioration of the catalyst were reported, but only limited effort has been made to relate the materials’ properties to the catalytic mechanism and performance. − To our knowledge, there exists presently no comprehensive review on NO x storage−reduction catalysis, where the importance of the material properties of the solid catalyst, such as chemical composition, structure, and morphology have been elucidated and related with the mechanism and performance of the storage−reduction process. In this review, at first, a brief overview is provided on the general features and mechanism of NSR catalysts (sections and ).…”

Section: Introductionmentioning

confidence: 99%

NO_x Storage−Reduction Catalysis: From Mechanism and Materials Properties to Storage−Reduction Performance

2009

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“…The high temperature capabilities of langasite, for example, make it a prime candidate as a crystal microbalance-based sensor for e.g. in-situ monitoring of automobile exhaust [3][4][5]. This not only requires that langasite retain its piezoelectric properties to high temperatures, but that it also remain stable in atmospheres ranging from highly reducing to oxidizing.…”

Section: Introductionmentioning

confidence: 99%

Defects and Transport in Langasite II: Donor-doped (La3Ga4.75Nb0.25SiO14)

Seh

Tuller

2005

J Electroceram

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The electrical conductivity of Nb doped langasite (La 3 Ga 4.75 Nb 0.25 SiO 14 ) was examined as a function of temperature and oxygen partial pressure by complex impedance spectroscopy. A pO 2 -independent regime was found at high pO 2 followed by a pO −1/6 2 dependent regime at low pO 2 . A defect model consistent with these results was derived in which the electron density n is fixed by the density of ionized Nb donors at high pO 2 and by the generation of oxygen vacancies at low pO 2 . The temperature and oxygen partial pressure dependence of the electron density was obtained independently by thermoelectric power measurements. The Nb donor ionization energy was determined to be 1.52 ± 0.06 eV, confirming Nb to be a deep donor in langasite. By combining conductivity and thermoelectric power data, an expression for the electron mobility given by µ e = 1.1 × 10 −2 exp(− 0.15±0.01eV kT ) was obtained. After evaluating the temperature dependent conductivity data under reducing conditions, in light of the defect model, a value for the reduction enthalpy (E r = 6.57 ± 0.24 eV) was derived.

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Recent Progress in NOx Trap Technology

Cited by 41 publications

References 5 publications

Defects and transport in langasite I: Acceptor-doped (La3Ga5SiO14)

Defects and transport in langasite I: Acceptor-doped (La3Ga5SiO14)

NO_x Storage−Reduction Catalysis: From Mechanism and Materials Properties to Storage−Reduction Performance

Defects and Transport in Langasite II: Donor-doped (La3Ga4.75Nb0.25SiO14)

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Recent Progress in NOx Trap Technology

Cited by 41 publications

References 5 publications

Defects and transport in langasite I: Acceptor-doped (La3Ga5SiO14)

Defects and transport in langasite I: Acceptor-doped (La3Ga5SiO14)

NOx Storage−Reduction Catalysis: From Mechanism and Materials Properties to Storage−Reduction Performance

Defects and Transport in Langasite II: Donor-doped (La3Ga4.75Nb0.25SiO14)

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Product

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NO_x Storage−Reduction Catalysis: From Mechanism and Materials Properties to Storage−Reduction Performance