First-principles study of structural and energetic properties of A_2Hf_2O_7 (A=Dy, Ho, Er) compounds

摘要

The structural and energetic properties of A_2Hf_2O_4 (A=Dy, Ho, Er) compounds have been investigated by means of ab initio total energy calculations. For Er_2Hf_2O_7 the defect fluorite structure is predicted to be more stable than pyrochlore structure, agreeing well with previous experimental [J. Inorg. Nucl. Chem. 31, 2367 (1969); J. Less Common Met. 14, 435 (1968)] and theoretical [J. Am. Ceram. Soc. 85, 2139 (2002)] investigations. In contrast to Er_2Hf_2O_7 pyrochlore, Dy_2Hf_2O_7 and Ho_2Hf_2O_7 prefer pyrochlore structures, which is consistent with the recent experimental observations of Dy_2Hf_2O_7 compound [J. Solid State Chem. 179, 1990 (2006)].