Structural refinement and thermal expansion of hexaborides

In the boron-framework of hexaborides, CaB6, SrB6, BaB6, YB6 and LaB6, the boron position was found to be adjusted so as to compensate the interaction between the cations. It was estimated from the boron position that a boron-boron bond between the boron octahedra has a 1.5 times higher force constant than that in the octahedron, which is consistent with the results of the neutron and Raman scattering experiments. In addition, the adjustment of the boron position well corresponded with the thermal expansion