TEM imaging of clustered Au substitutional impurities in YBa2Cu3O6.9

✍ Scribed by B.G. Storey; M.A. Kirk; L.D. Marks

• Publisher: Elsevier Science
• Year: 1995
• Tongue: English
• Weight: 553 KB
• Volume: 246
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/0921-4534(95)00125-5

✦ Synopsis

Evidence for clustering of Au impurity atoms into randomly distributed 1-2 nm rods is presented for YBa2Cu30 7_ (8 < 0.1) grown by the self-flux technique in Au crucibles. Electron-diffraction patterns show very weak diffuse streaks along ( 100) and ( 010), and these streaks persist over several degrees of tilt indicating rod-like defects. Multislice image simulations, including the effect of amorphous carbon, for a variety of defect types are compared to high-resolution images. The model that best fits the experimental data is defects made up of 3-4 unit cell long Au-O vacancy rods along (010) and Au-O interstitial rods along (100). In light of flux-pinning data comparing YBCO crystals with and without Au doping, these defects should be considered as flux-pinning sites in as-grown Au doped crystals.