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, Dy(4)C(3) and Dy(3)C(2), and dysprosium sesquicarbide Dy(2)C(3) previously known only at ambient conditions. The structure of Dy(4)C(3) was found to be closely related to that of dysprosium sesquicarbide Dy(2)C(3) with the Pu(2)C(3)-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.