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MgHf(WO4)3 exhibits orthorhombic structure with negative thermal expansion above 400K. Study compares monoclinic and isotructural phases, showcasing volume expansion data.
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A New Structure in the Sc2W3O12 Family of Negative Thermal Expansion CompoundsCora Lind, The University of Toledo, DMR 0545517 MgHf(WO4)3 was prepared by high-energy ball milling and subsequent calcination. X-ray and neutron diffraction studies have shown that it adopts a monoclinic structure at room temperature, and transforms to a new, orthorhombic structure with negative thermal expansion behavior above 400 K. In contrast, the mono-clinic phase is iso-structural to mono-clinic Al2(MoO4)3. Volume expansion of MgHf(WO4)3 from neutron and X-ray diffraction data, and students packing a neutron sample at NIST. Gindhart et al. J. Mater. Res. 2007 ACA Etter Student Award 2007
A New Structure in the Sc2W3O12 Family of Negative Thermal Expansion CompoundsCora Lind, The University of Toledo, DMR 0545517 Education: Three undergraduate (M. Broderick, K. Carroll, K. Witker), one high school student (S. Kraemer) and four graduate students (S. Gates, A. Gindhart, L. Kozy, N. Pedoussaut) have been working in the PI’s lab. Broderick, Carroll (both 2006), Witker and Kraemer (both 2007) were supported by this grant for summer research. The Lind group participated in several educational/outreach projects to introduce the general public to science and challenges related to thermal expansion. “Dreams to Reality” workshop for girls at the local science museum. Two attendees proudly display their ball-and-spring models of positive and negative thermal expansion materials.