Nitrogen‐doped zirconia single crystals

Abstract

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.

Ionic and electronic conductivity of nitrogen-doped YSZ single crystals

“…In this study x is fixed to 0.095 and n is varied in the range 0-0.12. Details of nitridation are published in a recent contribution [7]. The typical dimensions of the crystals used for impedance measurements were rod-like of dimensions 10× 1 × 1 mm 3 .…”

“…Different approaches were applied to incorporate nitrogen into YSZ -high temperature treatment [7,8], electrochemical incorporation [9] and pulsed laser deposition (PLD) [10] with a maximum concentration of 2.4 wt.% nitrogen in YSZ as reported by Lerch [6,7]. The incorporation into pure ZrO 2 leads to the cubic γ-phase or to ordered β-type-phases with a lower symmetry [4,11].…”

Electrochemical activation of molecular nitrogen at the Ir/YSZ interface

“…In order to shift the equilibrium in eqn (1) to the right, either a significant decrease of the oxygen activity is required or nonequilibrium techniques have to be applied. Different approaches have been applied to incorporate nitrogen into oxide materials: (i) a thermochemical approach (in the temperature range 1473 o T/K o 2673), 18 (ii) pulsed laser deposition (PLD), 19 and (iii) an electrochemical approach. 20,21 The difference between these three methods can be illustrated by decomposing eqn (1) into two reactions: In approach (i) the electrons required for reaction (4) to proceed are generated by reaction (3) proceeding towards the left (i.e.…”

An EMF cell with a nitrogen solid electrolyte—on the transference of nitrogen ions in yttria-stabilized zirconia

“…Details of the nitridation and characterization of the samples are presented elsewhere. 17 A single crystal of nitrogen-free YSZ (CrysTec GmbH, Berlin) was also employed for the purpose of comparison with the N-doped specimen, as well as for confirming the validity of the present experiment. on each surface of the disk under a light spring pressure applied through the alumina sheath carrying platinum wire.…”