“…Double nitrates of alkali metals and lanthanides of the composition A 3 Ln 2 (NO 3 ) 9 have been found to crystallize in the chiral space groups P4 1 32 and P4 3 32 (Wickleder, 2002). After the first finding of K 3 Pr 2 (NO 3 ) 9 by Carnall et al (1973), this structure type has been observed in several compounds, to date with K (Carnall et al, 1973;Vigdorchik et al, 1992;Guillou et al, 1995;Gobichon et al, 1999), Rb (Vigdorchik et al, 1990;Manek & Meyer, 1993a;Guillou et al, 1996), and NH 4 (Manek & Meyer, 1992) as 'A 0 cations for the lighter lanthanides La-Sm, and also detached examples with Na at the 'A 0 site (Stockhause & Meyer, 1997;Luo & Corruccini, 2004) and Eu (Manek & Meyer, 1992), Gd (Manek & Meyer, 1992;Luo & Corruccini, 2004), and even Bi (Goaz et al, 2012) at the lanthanide site have been reported. The compounds are typically synthesized by dissolving the lanthanide oxides or nitrates in melts of the respective alkali metal or ammonium nitrates under anhydrous atmosphere, while lanthanum and cerium compounds have been crystallized from solutions in H 2 O or HNO 3 (Guillou et al, 1995(Guillou et al, , 1996Gobichon et al, 1999).…”