| About this Abstract |
| Meeting |
MS&T22: Materials Science & Technology
|
| Symposium
|
Phase Transformations in Ceramics: Science and Applications
|
| Presentation Title |
HfW2O8 and Hf1-xTixW2O8 Negative Thermal Expansion and Phase Transformation |
| Author(s) |
Benjamin Hulbert, Dylan Blake, Kuo-Pin Tseng, Waltraud Kriven |
| On-Site Speaker (Planned) |
Benjamin Hulbert |
| Abstract Scope |
HfW2O8 has been the focus of many thermal expansion studies due to its isotropic negative thermal expansion shown previously at temperatures below 700 ℃ as well as the P213 to PaŻ3 phase transformation at 190 ℃. This presents the first thermal expansion measurement of HfW2O8 at its equilibrium temperature range of 1100 ℃ to 1275 ℃. The mechanism behind this negative thermal expansion is discussed. The Hf1-xTixW2O8 solid solution from x = 0.01 to 0.07 was studied to determine how Ti4+ substitution affects the phase transformation, thermal expansion, and WO4 tetrahedra disorder. Powdered samples were synthesized via the organic-inorganic steric entrapment method. Crystallized powdered samples mounted in fused-silica capillaries underwent in-situ, high temperature characterization at the National Synchrotron Light Source II and the Advanced Photon Source in a quadrupole lamp optical furnace to achieve elevated temperatures from 25 ℃ to 1400 ℃ in air. |