Neutron powder diffraction studies have been performed for the Heusler compound 'CoTiSn' prepared from stoichiometric amounts of the constituent elements and its nitrogenation products. The Rietveld refinement indicates that the 'CoTiSn' sample consists of three phases: Co+Ti+Sn→0.69Co1.50TiSn+0.05Ti6Sn5+0.06Sn. It is concluded that the stoichiometric compound CoTiSn is not synthesized but that Co1.50TiSn with a half-filled vacancy sublattice in the MgAgAs-type structure which has the XYZ configuration is formed. Nitrogen absorption is accompanied by the disproportionation of the 'CoTiSn' sample according to the following equation: 'CoTiSn'+0.23N2→0.50Co1.92TiSn+0.47TiN+0.36Sn+0.04CoS n2+0.03Co1.50TiSn. It is revealed that nitrogen atoms react selectively with Ti atoms in the Co1.50TiSn and Ti6Sn5 compounds and that nitrogen-induced occupation of the vacancy site in Co1.50TiSn by Co atoms takes place during nitrogenation; Co1.92TiSn with the Cu2MnAl-type structure is formed.
|ジャーナル||Journal of Alloys and Compounds|
|出版ステータス||Published - 2002 12月 16|
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