Phase formation in the Li2MoO4–K2MoO4–In2(MoO4)3 system and crystal structures of new compounds K3InMo4O15 and LiK2In(MoO4)3

XRD study of solid-phase interaction in the Li2MoO4–K2MoO4–In2(MoO4)3 system was performed. The boundary K2MoO4–In2(MoO4)3 system is an non-quasibinary join of the K2O–In2O3–MoO3 system where a new polymolybdate K3InMo4O15 isotypic to K3FeMo4O15 was found. In the structure (а=33.2905(8), b=5.8610(1), c=15.8967(4) Å, β=90.725(1)°, sp. gr. C2/c, Z=8, R(F)=0.0407), InO6 octahedra, Mo2O7 diortho groups and MoO4 tetrahedra form infinite ribbons {[In(MoO4)2(Mo2O7)]3−}∞ along the b-axis. Between the chains, 8- to 10-coordinate potassium cations are located. A subsolidus phase diagram of the Li2MoO4–K2MoO4–In2(MoO4)3 system was constructed and a novel triple molybdate LiK2In(MoO4)3 was revealed. Its crystal structure (a=7.0087(2), b=9.2269(3), c=10.1289(3) Å, β=107.401(1)°, sp. gr. P21, Z=2, R(F)=0.0280) contains an open framework of vertex-shared MoO4 tetrahedra, InO6 octahedra and LiO5 tetragonal pyramids with nine- and seven-coordinate potassium ions in the framework channels.