A new family of isostructural titanates, MLi2Ti6O14 (M = Sr, Ba, Pb)

The existence of isostructural titanates with a composition corresponding to the formula MLi2Ti6O14 has been evidenced in the ternary oxide systems MO–Li2O–TiO2 (M = Sr, Ba, Pb). Single crystals of these compounds have been grown by the flux method using LiBO2 as a high-temperature solvent. The structure, as determined by single crystal X-ray diffraction is orthorhombic (space group Cmca (no. 64), Z = 8) with (i) a = 16.570(5) A, b = 11.150(2) A, c = 11.458(2) A, V = 2116.9(8) A3, R1 = 0.039, w R2 = 0.087 for SrLi2Ti6O14; (ii) a = 16.577(1) A, b = 11.273(1) A, c = 11.581(1) A, V = 2164.2(5) A3, R1 = 0.018, w R2 = 0.047 for BaLi2Ti6O14 and (iii) a = 16.649(1) A, b = 11.146(1) A, c = 11.494(1) A, V = 2132.9(5) A3, R1 = 0.033, w R2 = 0.078 for PbLi2Ti6O14. A three-dimensional framework of edge and corner sharing TiO6 octahedra sets up the crystal structure. Lithium occupies the tetrahedral vacancies, while M atoms are located at 11-oxygen coordinated sites.