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Effect of Yttria Content on the Zirconia Unit Cell Parameters

Authors


  • This investigation was supported by the National Science Foundation under Grant DMR-0605700 and by the US Department of Energy via Cooperative Agreement DE-FC26-05NT42643. Any opinions, findings, conclusions or other recommendations expressed are those of the authors and do not necessarily reflect the views of the US Department of Energy or the National Science Foundation. The research made use of the UCSB-MRL Central Facilities supported by NSF under grant DMR-0080034. Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. ML gratefully acknowledges support of the International Center for Materials Research through the UCSB-MPG Program for International Exchange in Materials Science.

Author to whom correspondence should be addressed. e-mail: jkoschmeder@engineering.ucsb.edu

Abstract

The relationship between yttria concentration and the unit cell parameters in partially and fully stabilized zirconia has been reassessed, motivated by the need to improve the accuracy of phase analysis upon decomposition of t′-based thermal barrier coatings. Compositions ranging from 6 to 18 mol% YO1.5 were synthesized and examined by means of high-resolution X-ray diffraction. Lattice parameters were determined using the Rietveld refinement method, a whole-pattern fitting procedure. The revised empirical relationships fall within the range of those published previously. However, efforts to achieve superior homogeneity of the materials, as well as accuracy of the composition and lattice parameters, provide increased confidence in the reliability of these correlations for use in future studies. Additional insight into the potential sources for scatter previously reported for the transition region (~12–14 mol% YO1.5), where tetragonal and cubic phases have been observed to coexist, is also provided. Implications on the current understanding of stabilization mechanisms in zirconia are discussed.

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