## Abstract

A combination of ab initio total-energy calculations and high-pressure x-ray diffraction experiments has been used to study the phase stability of Y-based 1:2 compounds. The motivation for these investigations was to clarify the origin of the change of the structure among the YT_{2} compounds (T = 3d transition element) between the neighbouring elements Ni (YNi_{2}: defect superstructure of cubic Laves phase C15) and Cu (YCu_{2}: orthorhombic CeCu_{2}-type structure). As a test of the ab initio calculations the cubic YAl_{2} Laves phase compound has been included in the investigations. The ab initio calculations confirm the reversal of the relative stabilities of the CeCu_{2} and C15 phases in YCu_{2} and YNi_{2} and give also the correct results for YAl_{2}. Furthermore a pressure-induced structural transition is predicted for YCu_{2}. The high-pressure x-ray experiments show that there is very good agreement between the calculated and the measured pressure dependence of the lattice parameters of YCu_{2} up to about 10 GPa. Above 10 GPa the structure starts to become irreversibly amorphous. This instability may be a hint at the structural phase transition predicted by the calculations.

Originalsprache | Englisch |
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Seiten (von - bis) | 2933-2945 |

Seitenumfang | 13 |

Fachzeitschrift | Journal of Physics Condensed Matter |

Jahrgang | 10 |

Ausgabenummer | 13 |

DOIs | |

Publikationsstatus | Veröffentlicht - 6 Apr. 1998 |

Extern publiziert | Ja |

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