Solvothermale Synthese und Bestimmung der Kristallstrukturen von AgBiI₄ und Ag₃BiI₆

Solvothermal Synthesis and Crystal Structure Determination of AgBiI 4 and Ag 3 BiI 6 AgBiI 4 and Ag 3 BiI 6 were synthesized by solvothermal reaction from AgI and BiI 3 in diluted HI‐solution (20 %) at a temperature of 160 °C. The greyish‐black crystals grow as octahedra (AgBiI 4 ) or hexagonal/trigonal platelets (Ag 3 BiI 6 ). AgBiI 4 crystallizes in space group Fd3¯m with a = 1222.3(1) pm (300 K) and Z = 8 whereas Ag 3 BiI 6 shows the space group R3¯m with a = 435.37(6) pm, c = 2081.0(4) pm (300 K) and Z = 1. Both crystal structures show stacking sequence abcabc… of hexagonal layers containing Iodine. Bismuth and silver are sharing octahedral sites with different mass ratio in both structures. The part of silver which could be localized varies with temperature. This behaviour indicates mobility of silver within the crystal structure. The ionic conductivity of AgBiI 4 is explored. AgBiI 4 and Ag 3 BiI 6 show close structural relationship, with AgBiI 4 as a variant with a higher degree of order.