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Title: Isotropic negative thermal expansion in ZrW2O8 and HfW2O8 from 1100 to 1275◦C
ZrW2O8 (ZrO2•2WO3) and HfW2O8 (HfO2•2WO3) have been the focus of thermal expansion studies due to their isotropic negative thermal expansion (NTE) measured previously at temperatures below 775◦C. This work presents measurements of these materials at their thermodynamically stable temperature ranges of 1105 and 1257◦C for ZrW2O8 and 1105–1276◦C for HfW2O8, where they were characterized with in situ, powder X-ray diffraction. The linear coefficients of thermal expansion were measured to be −5.52 × 10−6 and −4.87 × 10−6◦C−1 for ZrW2O8 and HfW2O8, respectively. The mechanism leading to this NTE is discussed. Powder samples were synthesized by a solution-based process called the organic–inorganic steric entrapment method. In situ characterization in air was carried out at the National Synchrotron Light Source II using a hexapole lamp, optical furnace and theAdvanced Photon Source using a quadrupole lamp, optical furnace to achieve elevated temperatures.  more » « less
Award ID(s):
Author(s) / Creator(s):
Tatsuki Ohji, Ph. D. Editor
Publisher / Repository:
Date Published:
Journal Name:
Journal of the American Ceramic Society
Edition / Version:
In press
Page Range / eLocation ID:
Subject(s) / Keyword(s):
["Equilibrium, HfW2O8, high temperature, in situ, isotropic, negative thermal expansion,\nsynchrotron radiation, ZrW2O8"]
Medium: X
Sponsoring Org:
National Science Foundation
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