The Structure of Yttrialite and Its Identification Using Laboratory and Synchrotron-Based Powder X-Ray Diffraction

Authors: Heward, William J.¹; Sarrafi-Nour, Reza²; Gao, Yan¹

Source: Journal of the American Ceramic Society, Volume 92, Number 2, February 2009 , pp. 511-516(6)

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Abstract:

A highly crystalline sample of the impurity stabilized phase y-Y₂Si₂O₇, generally known as yttrialite, has been formed from the melt of a glass with a nominal composition of 62(SiO₂)-10(Al₂O₃)-28(Y₂O₃) mol%. Powder X-ray diffraction patterns were collected using in-house instrumentation and the 11-BM diffractometer at the Advanced Photon Source, Argonne National Laboratory, Argonne, IL. Rietveld refinements were carried out on the patterns using two structural models. On patterns collected using in-house instrumentation the correct structure assignment was difficult to determine; however, the extremely high-quality data afforded by the 11-BM instrument showed conclusively that the sample was found to crystallize in the monoclinic system (SG=P2₁/m) with lattice parameters a=5.03032(6), b=8.06892(6), c=7.33620(6) Å, and β=108.673(1). Furthermore, simulations have shown that it is likely that this structure model can be used to describe natural yttrialite or yttrialite that is formed at low temperatures, though the possibility that such materials are paracrystalline is also discussed.

Document Type: Research article

DOI: http://dx.doi.org/10.1111/j.1551-2916.2008.02916.x

Affiliations: 1: Chemical and Structural Analysis Laboratory, GE Global Research Center, Niskayuna, New York 12309 2: GE Global Research Center, Ceramic and Metallurgy Technologies, Niskayuna, New York 12309

Publication date: 2009-02-01