NaNb6Cl15 – Preparation,Structure, Ionic Conduction

NaNb₆Cl₁₅ is prepared by heating Nb₃Cl₈, NaCl and Nb under Ar at 1 170 < T K] < 1 270 forming black regular dodecahedra. It crystallizes in the cubic space group Ia3 d (a = 2 041.7(2) pm at room temperature) and transforms to a tetragonal structure below 150 K (probably I4₁/acd, a = 2 037.2(6), c = 2 028.2(2) pm at 80 K). The Na⁺ ions are at room temperature dynamically disordered in a split position. Their mobility is investigated by IR spectroscopy and electrochemical methods.