High-pressure synthesis of dysprosium carbides

Chemical reactions between dysprosium and carbon were studied in laser-heated diamond anvil cells at pressures of 19, 55, and 58 GPa and temperatures of ∼2500 K. In situ single-crystal synchrotron X-ray diffraction analysis of the reaction products revealed the formation of novel dysprosium carbides, Dy₄C₃ and Dy₃C₂, and dysprosium sesquicarbide Dy₂C₃ previously known only at ambient conditions. The structure of Dy₄C₃ was found to be closely related to that of dysprosium sesquicarbide Dy₂C₃ with the Pu₂C₃-type structure. Ab initio calculations reproduce well crystal structures of all synthesized phases and predict their compressional behavior in agreement with our experimental data. Our work gives evidence that high-pressure synthesis conditions enrich the chemistry of rare earth metal carbides.