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Carbon vacancy ordering in zirconium carbide powder
Author(s) -
Zhou Yue,
Heitmann Thomas W.,
Bohannan Eric,
Schaeperkoetter Joseph C.,
Fahrenholtz William G.,
Hilmas Gregory E.
Publication year - 2020
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.16964
Subject(s) - materials science , neutron diffraction , selected area diffraction , zirconium , carbon fibers , powder diffraction , crystallography , zirconium carbide , vacancy defect , rietveld refinement , carbide , electron diffraction , transmission electron microscopy , crystal structure , diffraction , metallurgy , chemistry , nanotechnology , composite material , physics , composite number , optics
Abstract Ordered carbon vacancies were detected in zirconium carbide (ZrC x ) powders that were synthesized by direct reaction. Zirconium hydride (ZrH 2 ) and carbon black were used as starting powders with the molar ratio of ZrH 2 :C = 1:0.6. Powders were reacted at 1300°C or 2000°C. The major phase detected by x‐ray diffraction (XRD) was ZrC x . No excess carbon was observed by transmission electron microscopy (TEM) in powders synthesized at either temperature. Ordering of the carbon vacancies was identified by neutron powder diffraction (NPD) and further supported by selected area electron diffraction (SAED). The vacancies in carbon‐deficient ZrC x exhibited diamond cubic symmetry with a supercell that consisted of eight (2 × 2 × 2) ZrC x unit cells with the rock‐salt structure. Rietveld refinement of the neutron diffraction patterns revealed that the synthesis temperature did not have a significant effect on the degree of vacancy ordering in ZrC x powders. Direct synthesis of ZrC 0.6 resulted in the partial ordering of carbon vacancies without the need for extended isothermal annealing as reported in previous experimental studies.