Regensburg 2007 – wissenschaftliches Programm

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MM: Fachverband Metall- und Materialphysik

MM 20: Poster session

MM 20.9: Poster

Dienstag, 27. März 2007, 14:45–18:00, Poster C

Formation of rare earth zirconia pyrochlores on yttria-stabilized ZrO₂ single crystals by solid state reactions — •Andreas Schubert, Stephan Senz, and Dietrich Hesse — Max Planck Institut für Mikrostrukturphysik, Weinberg 2, 06120 Halle

RE₂Zr₂O₇ (RE=La, Pr, Nd, Sm, Gd, Ho)-based pyrochlore islands were grown on Y₂O₃-stabilized ZrO₂ (YSZ) single-crystals by reaction between RE₂O₃ and YSZ. After a vapour-solid reaction at 1200 ^∘C at a rate of 0.6 nm/min for 6.5 min between La₂O₃ vapour and YSZ(001), islands with eight domains were formed. Four domains were tilted by 2.1^∘ around <110> and the other four were tilted by 0.9^∘ around <100>. To understand this effect, other experiments were performed with different substrate orientations and other rare earth oxides, to study the influence of the misfit. La₂Zr₂O₇ (LZO) has a relatively large misfit to YSZ of 5 % but other rare earth-based pyrochlores have lower misfits of 4.0 % (Pr₂Zr₂O₇) to 1.2 % (Ho₂Zr₂O₇). The reaction products were investigated by AFM, XRD and TEM. On YSZ(110), four domains were found by XRD pole figure measurements, two were tilted around [110] with a maximum at a tilt angle of 0.6^∘ and the other two were tilted by 0.9^∘ around [001]. AFM and TEM plan-view images show stripe-shaped islands with the long edge along [110] and the short edge along [001]. In addition to these vapour-solid reactions some experiments with solid-solid reactions were performed. For the solid-solid reaction of La₂O₃ and YSZ(001) it was determined by XRD-measurements that the relation (001)LZO ∥ (001)YSZ is valid without any systematic tilt (FWHM=0.5^∘).