Directions of zero thermal expansion in anisotropic oxides
November 10-14, 2019
Figure 13. – Quadric surface visualizing the coefficients of thermal expansion of HfTiO4 at room temperature. Blue is positive, red is negative and yellow represents directions of zero thermal expansion.
Oxide materials often have anisotropic crystal structures, which can result in direction-dependent material properties. While they typically have positive coefficients of thermal expansion, it has been observed that some oxide materials can have directions of negative thermal expansion over certain temperature ranges. Such materials, having both positive and negative coefficients of thermal expansion, must also have particular directions in which the thermal expansion is zero. Using the Quadrupole Lamp Furnace (QLF) developed in the Kriven group at the University of Illinois at Urbana Champaign, high-temperature in-situ x-ray diffraction has been performed at the National Synchrotron Light Source II (NSLS II) X-ray powder diffraction beamline (XPD – 28-ID) to track directions of zero thermal expansion in orthorhombic HfTiO4. These results have important implications for the design of composites for high-temperature applications.
Please click Additional Files below to see the full abstract.
Scott J. McCormack, William A. Wheeler, Benjamin S. Hulbert, and Waltraud M. Kriven, "Directions of zero thermal expansion in anisotropic oxides" in "Composites at Lake Louise 2019", John Kieffer, University of Michigan, USA Erik Spoeke, Sandia National Laboratories, USA Meisha Shofner, Georgia Institution of Technology, USA Eds, ECI Symposium Series, (2019). https://dc.engconfintl.org/composites_all_2019/31