Deposition and mechanical properties of polycrystalline Y2O3/ZrO2 superlattices

Philip C. Yashar, Scott A. Barnett, Lars Hultman, William D. Sproul

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Polycrystalline Y2O3/ZrO2 superlattice thin films were deposited using opposed-cathode reactive magnetron sputtering. Pulsed direct-current power was used to eliminate arcing on the metallic targets. Radio-frequency power was applied to the substrates to achieve ion bombardment of the growing film. In order to reproducibly deposit at high rates in Ar-O2 mixtures, the Y target voltage was used to indirectly feedback-control the O2 partial pressure. Deposition rates as high as approximately 70% of the pure metal rates were achieved, typically 3.5 μm/h. Superlattices with periods ranging from 2.6 to 95 nm were deposited. Y2O3 layer thicknesses were either 75% or 50% of the superlattice period. X-ray diffraction and transmission electron microscopy studies showed well-defined superlattice layers. The ZrO2 layers exhibited the high-temperature cubic-fluorite structure, which was epitaxially stabilized by the cubic Y2O3 layers, for thicknesses ≤7 nm. The equilibrium monoclinic structure was observed for thicker ZrO2 layers. Nanoindentation hardnesses ranged from 11.1 to 14.5 GPa with little dependence on period. The hardness results are discussed in terms of current superlattice hardening theories.

Original languageEnglish (US)
Pages (from-to)3614-3622
Number of pages9
JournalJournal of Materials Research
Volume14
Issue number9
DOIs
StatePublished - Sep 1999

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering

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