From zirconia to yttria: Sampling the YSZ phase diagram using sputter-deposited thin films

• Published in: AIP advances Vol. 6; no. 2; pp. 025119 - 025119-20
• Main Authors: Götsch, Thomas, Wallisch, Wolfgang, Stöger-Pollach, Michael, Klötzer, Bernhard, Penner, Simon
• Format: Journal Article
• Language: English
• Published: Melville American Institute of Physics 01.02.2016; AIP Publishing LLC
• Subjects: Atomic force microscopy; Crystal structure; Cube texture; Electron diffraction; Energy dispersive X ray spectroscopy; Energy transmission; Ion beam sputtering; Phase diagrams; Phase transitions; Stoichiometry; Substrates; Texturing; Thin films; Transmission electron microscopy; Yttria-stabilized zirconia; Yttrium oxide; Zirconium dioxide
• ISSN: 2158-3226; 2158-3226
• DOI: 10.1063/1.4942818

Yttria-stabilized zirconia (YSZ) thin films with varying composition between 3 mol% and 40 mol% have been prepared by direct-current ion beam sputtering at a substrate temperature of 300 °C, with ideal transfer of the stoichiometry from the target to the thin film and a high degree of homogeneity, as determined by X-ray photoelectron and energy-dispersive X-ray spectroscopy. The films were analyzed using transmission electron microscopy, revealing that, while the films with 8 mol% and 20 mol% yttria retain their crystal structure from the bulk compound (tetragonal and cubic, respectively), those with 3 mol% and 40 mol% Y2O3 undergo a phase transition upon sputtering (from a tetragonal/monoclinic mixture to purely tetragonal YSZ, and from a rhombohedral structure to a cubic one, respectively). Selected area electron diffraction shows a strong texturing for the three samples with lower yttria-content, while the one with 40 mol% Y2O3 is fully disordered, owing to the phase transition. Additionally, AFM topology images show somewhat similar structures up to 20 mol% yttria, while the specimen with the highest amount of dopant features a lower roughness. In order to facilitate the discussion of the phases present for each sample, a thorough review of previously published phase diagrams is presented.