Ternary arsenide Ba0.8Hf12As17.7, a variant of the Cr12P7 structure type with inserted arsenic ribbons

A study is conducted on the nonstoichiometric ternary arsenide Ba0.8Hf12As17.7. The compound was synthesized by reacting the elements at 950 degrees Centrigrade in a tin flux. It is shown that Ba0.8Hf12As17.7 exhbits the unique feature of As ribbons inserted between isolated columnar assemblies of Hf6 trigonal prisms. The behavior and features of As-As bonding in Ba0.8Hf12As17.7 were also determined using extended Huckel band structure calculations.