An Improved Synthesis of Ternary Carbonates: The Examples LiLa(CO 3 ) 2 and La(CO 3 )F

The ternary carbonate LiLa(CO 3 ) 2 , previously obtained under supercritical CO 2 pressure conditions was prepared by a new and efficient way of synthesis. A 2:1 molar mixture of Li 2 (CO 3 ) and LaCl 3 reacted in a silica tube at 400 °C. The crystal structure of LiLa(CO 3 ) 2 was refined from X‐ray single‐crystal data and can be related with a caesium chloride type arrangement, where Li + and La 3+ ions occupy the cesium positions and (CO 3 ) 2– ions occupy all cubic voids. Cerium‐doped samples (LiLa(CO 3 ) 2 :Ce) exhibit blue luminescence. The mineral bastnäsite was synthesized by the same preparative approach, departing from a 1:1 molar mixture of LaF 3 and Li 2 (CO 3 ) being reacted at 450 °C.