Potassium lithium carbonate, KLiCO3:: single-crystal X-ray structure analysis and thermal expansion

Single crystals of KLiCO3, the intermediate compound in the eutectic system K2CO3-Li2CO3, were synthesized from the melt and the crystal structure was redetermined at room temperature by single-crystal X-ray diffraction: a = 7.232(1) Angstrom, b = 7.085(2) Angstrom, c = 6.579(1) Angstrom, beta = 113.40(1)degrees, space group P2(1)/n (No 14), Z = 4. Earlier literature results obtained by neutron time-of-night powder diffraction are corroborated. The structure is composed of distorted face and edge sharing LiO5 and KO9 coordination polyhedra which are arranged in a layered manner and are connected by distorted but planar carbonate anions. In addition to the structure analysis, the thermal expansion of the crystal was measured and analyzed up to melting at 504.5 degreesC. It exhibits a significant anisotropy with a maximum in direction c* about three times as large as the almost equal expansions in the a, b plane. This anisotropy is clearly understood from the distribution of bonds in the structure rather than from its layered nature.