HF-Free synthesis of colloidal Cs 2 ZrF 6 and (NH 4 ) 2 ZrF 6 nanocrystals.

A solution-phase synthesis of colloidally stable A 2 BF 6 nanocrystals is reported for the first time, focusing on A + = Cs + , NH 4 + and B 4+ = Zr 4+ . Handling hypertoxic HF is avoided by using NH 4 F and a low-boiling-point alcohol, representing the first synthesis of any A 2 BF 6 nanocrystals without HF addition. The chemical incompatability of Zr 4+ with other common fluoride sources is discussed.