Study on the addition of nonmetal interstitial atoms to the yttrium lattice: formation of YB x , YC x and YN x alloys

Yttrium is a rather rare and reactive met al. Due to these characteristics it absorbs important quantities of light atoms in its void spaces. Here, we present a study where B, C and N atoms are gradually incorporated into the octahedral interstices of Y. The idea is to model, by first‐principles calculations in a supercell approach, several stages of nonmetal assimilation in the yttrium lattice. In this case to develop YB x , YC x and YN x alloys. This study is limited to the cubic close‐packed stacking of Y and chemical compositions in the 0 ≤ x ≤ 1 range. We found that the studied alloys become thermodynamically favored. The cohesive energies improve with the addition of the nonmetal atoms. Besides, the cell volume and the bulk modulus vary differently for each kind of added atom. We come upon the fact that the ratio between cohesive energy and cell volume is strikingly better for YN x . We conclude that these alloys permit a remarkable degree of modulation in their properties and electronic structures by means of chemical composition. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)