September 2015
Rapid Communications of the American Ceramic Society
2691
capacities ranged from 495 to 439 Jꢀ(kgꢀK)ꢁ1 and thermal
conductivity decreased from 141 to 100 Wꢀ(mꢀK)ꢁ1 with
increasing Hf content. Not only do heat capacity and ther-
mal conductivity values of ZrB2 change systematically with
the Hf content, but most of the thermal properties
reported for ZrB2 ceramics to date are also impacted by
the presence of impurities such as Hf. Although the value
of 141 Wꢀ(mꢀK)ꢁ1 is the highest reported value for a poly-
crystalline ZrB2 ceramic to date, the intrinsic value is likely
to be even higher based on the presence of small amounts
of ZrO2 and carbon impurities in the RHP (Zr,Hf)B2
ceramics.
Acknowledgments
This research was supported by the National Science Foundation through
grant number DMR 0906584.
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