Publications Repository - Helmholtz-Zentrum Dresden-Rossendorf

AlYB₁₄ (Imma) thin films were synthesized by magnetron sputtering. Based on X-ray diffraction, no phases other than crystalline AlYB₁₄ could be identified. According to electron probe microanalysis, energy dispersive X-ray analysis and elastic recoil detection analysis, the Al and Y occupancy varies in the range of 0.73 to 1.0 and 0.29 to 0.45, respectively. Density functional theory based calculations were carried out to investigate the effect of occupancy on the stability of Al_xY_yB₁₄ (x, y = 0.25, 0.75, 1). The mean effective charge per icosahedron and the bulk moduli were also calculated. It is shown that the most stable configuration is Al_0.5YB₁₄, corresponding to a charge transfer of 2 electrons to the boron icosahedra. Furthermore, it is found that the stability of a configuration is increased if the charge is homogeneously distributed within the icosahedra. The bulk moduli for all investigated configurations are in the range between 196 and 220 GPa, rather close to known hard phases such as α-Al₂O₃.