Nitrogen Tracer Diffusion in Yttria Doped Zirconium Oxonitride

Taylor, Chris; Kilo, Martin; Argirusis, Christos; Borchardt, Günter; Valov, Ilia; Korte, Carsten; Janek, Jürgen; Rödel, T.‐C.; Lerch, Martin

doi:10.4028/www.scientific.net/ddf.237-240.479

Cited by 13 publications

(10 citation statements)

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“…In our experiments we cannot distinguish between oxidation of nitrogen and oxide ions, but because of the more negative electrode potential of the N 3À /N 2 redox couple we expect that firstly the nitrogen ions will be oxidized. However, because of the lower mobility of N 3À in the volume of the crystal 13 and the much higher concentration of oxide ions the recorded currents are mainly due to the oxygen evolution reaction. We suggest that the passivation-like state at overvoltages above 0.6 V appears due to accumulation (adsorption) of product(s) of the reaction at the interface and not due to a formation of ion blocking IrO x and/or insulating layers from impurities e.g.…”

Section: Current-voltage Measurements-anodic Oxidationmentioning

confidence: 99%

Electrochemical activation of molecular nitrogen at the Ir/YSZ interface

Valov

Luerßen

Mutoro

et al. 2011

Phys. Chem. Chem. Phys.

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Nitrogen is often used as an inert background atmosphere in solid state studies of electrode and reaction kinetics, of solid state studies of transport phenomena, and in applications e.g. solid oxide fuel cells (SOFC), sensors and membranes. Thus, chemical and electrochemical reactions of oxides related to or with dinitrogen are not supposed and in general not considered. We demonstrate by a steady state electrochemical polarisation experiments complemented with in situ photoelectron spectroscopy (XPS) that at a temperature of 450 1C dinitrogen can be electrochemically activated at the three phase boundary between N 2 , a metal microelectrode and one of the most widely used solid oxide electrolytes-yttria stabilized zirconia (YSZ)-at potentials more negative than E = À1.25 V. The process is neither related to a reduction of the electrolyte nor to an adsorption process or a purely chemical reaction but is electrochemical in nature. Only at potentials more negative than E = À2 V did new components of Zr 3d and Y 3d signals with a lower formal charge appear, thus indicating electrochemical reduction of the electrolyte matrix. Theoretical model calculations suggest the presence of anionic intermediates with delocalized electrons at the electrode/electrolyte reaction interface. The ex situ SIMS analysis confirmed that nitrogen is incorporated and migrates into the electrolyte beneath the electrode.

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Section: Current-voltage Measurements-anodic Oxidationmentioning

confidence: 99%

Electrochemical activation of molecular nitrogen at the Ir/YSZ interface

Valov

Luerßen

Mutoro

et al. 2011

Phys. Chem. Chem. Phys.

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“…1) is the same as found for ceramics [4,6]. The homogeneity of the crystals was verified by secondary ion mass spectrometry (SIMS), micro x-ray fluorescence spectroscopy (µ-XRF), and neutron diffraction [8,9,14,15]. At temperatures higher than 1700°C it is difficult to obtain high nitrogen contents in the fluorite-type crystal because of the above described thin surface layer consisting of rock salt-type M-Zr-O-N-C phases.…”

Section: Resultsmentioning

confidence: 90%

“…Dependent on the kind of cationic dopant and the ratio dopant cation / nitrogen, phases with randomly distributed (Y 2 O 3 or CaO) or ordered (MgO or Sc 2 O 3 ) anion vacancies are observed [4,6,7]. While the ordered phases are of great interest in crystal chemistry because of their complex ordering schemes, yttria-and calcia-doped materials are, to our knowledge, the first examples of solids with a high mobility of nitrogen anions, as shown recently by tracer diffusion experiments [8][9][10]. Furthermore, the ionic conductivity of nitrogen-doped zirconia is superior compared to pure cationdoped materials at temperatures above 1100°C [11].…”

Section: Introductionmentioning

confidence: 99%

Nitrogen‐doped zirconia single crystals

Rödel¹,

Wang

Lerch

et al. 2006

Cryst. Res. Technol.

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The aim of this work is the preparation of nitrogen-doped single crystals of cation-stabilized zirconia. Thin plates of these crystals were nitrided in a graphite heated resistance furnace with nitrogen as reaction gas. Several dwell times and reaction temperatures were tested and their effect on the amount of incorporated nitrogen is investigated. During nitridation at high temperatures a rock salt-type 'ZrN' layer grows on the surface, leading to the destruction of the crystal. In contrast to the fluorite-type bulk material, which can be described as a fast anion conductor, the surface layer shows electronic conductivity. For possible applications of the bulk material (solid electrolyte) the formation of the surface layer must be avoided. Therefore, the interface between surface epilayer and bulk material was investigated in detail by electron microscopy methods.

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“…In the last years several investigations on nitrogen ion mobility in nitrogen-doped zirconia-based materials have been carried out, revealing that nitrogen ion mobility can be principally realized and may be used for new applications requiring fast nitrogen ion conduction [6][7][8][9][10]. However, all investigations were carried out either on polycrystalline samples or on single crystals exhibiting the cubic fluorite-type phase even before nitrogen incorporation.…”

Section: Introductionmentioning

confidence: 99%