Double molybdates of Cs2R22+(MoO4)3 (R = Ni, Co, Mg, Mn, Cd) composition and crystal structure of Cs2Co2(MoO4)3

Double molybdates of Cs2R2(MoO4)3 (R=Ni, Co, Mg, Mn, Cd) composition having K2Mg2(SO4)3 langbeinite type structure are synthesized, (pseudo)cubic elementary cell parameters are determined, the melting temperatures and character are stated. Crystal structure of Cs2CO2(MoO4)3 (a10.832(5), b=10.829(5), c=10.830(5) A, sp.gr. P212121, Z=4, autodiffractometer ''Sintex P21'', MoKα-radiation, 3881 unique reflections, R=0.069) is interpreted. Mo-tetrahedrons and Co-octahedrons alternating in the structure form bound with common vertices three-dimensional langbeinite skeleton in which large ellipsoid voids cesium atoms are placed. Deviation of the structure from the cubic form is caused by minor mutual turns of Mo-tetrahedrons. The investigated binary molybdates are supposed to have a series of phase transitions