Synthesis of ZrCx with controlled carbon stoichiometry by low temperature solid state reaction

Zirconium carbide (ZrCx) powders were synthesized at temperatures between 1300 degrees C and 2000 degrees C by solid state reaction of zirconium hydride (ZrH2) and carbon black. Crystal structure, lattice parameters, and grain sizes of the as-synthesized ZrCx powders were characterized for two different starting ZrH2:C ratios of 1:0.60 and 1:0.98. Powders with stoichiometry approaching ZrC0.98 were synthesized at temperatures as low as 1600 degrees C whereas ZrCx powders synthesized at lower temperatures had lower carbon contents regardless of the starting ZrH2:C ratio. Crystallite sizes as small as about 50 nm were obtained due to the low synthesis temperature. Oxygen dissolved into the ZrCx lattice when carbon vacancies were present. Neutron diffraction analysis was used to determine that carbon stoichiometry increased and dissolved oxygen content decreased as synthesis temperature increased.