@Article{CrystGrowth&Des_12_1124, author = {H. Hagemann and V. D'Anna and L.M. {Lawson Daku} and F. Kubel}, title = {{Crystal chemistry in the barium fluoride chloride system}}, journal= {Cryst. Growth & Des.}, ISSN = {1528-7483}, volume= {12}, number= {3}, pages = {1124-1131}, url = {http://pubs.acs.org/doi/abs/10.1021/cg201588s}, eprint= {http://www.unige.ch/sciences/chifi/publis/refs_pdf/ref01282.pdf}, doi= {10.1021/cg201588s}, abstract = {{The crystal chemistry of the barium fluoride chloride system is studied both experimentally and theoretically. Different synthetic approaches yield nanocrystalline materials as well as large single crystals. The crystalline phases identified so far are BaFCl, Ba$_{12}$F$_{19}$Cl$_{5}$ and Ba$_{7}$F$_{12}$Cl$_{2}$ (in two modifications) and compared with analogous compounds. It is demonstrated that the compound Ba$_{2}$F$_{3}$Cl reported by Fessenden and Lewin 50 years ago corresponds to Ba$_{7}$F$_{12}$Cl$_{2}$. The phase diagram of the BaCl$_{2}$ {\frac{ }{ }} BaF$_{2}$ system is reinvestigated for fluoride mole fractions between 0.5 and 1. The peritectic formation of Ba$_{12}$F$_{19}$Cl$_{5}$ is observed. Periodic DFT calculations are performed for all structures in this system, including a hypothetical structure for Ba$_{2}$F$_{3}$Cl, based on the experimental structure of Ba$_{2}$H$_{3}$Cl. The energy of formation of the different barium fluoride chloride compounds from BaCl$_{2}$ and BaF$_{2}$ (normalized for one barium atom per formula unit), as calculated by DFT at 0K, is within only about ± 15 kJ/mol. Comparison with recent experimental results on calcium and strontium hydride chloride (bromide) compounds, suggest the possibility of a mutual exclusion between the M$_{2}$X$_{3}$Y and M$_{7}$X$_{12}$Y$_{2}$ (M = Ca, Sr, Ba, Pb, X = H, F, Y = Cl,Br) structures. The single crystal structure of PbFBr is also reported.}}, year = {2012} }