Other Chloro and Bromo Elpasolites

Other chloro elpasolites are obtained by the same preparative route by selecting the appropriate starting materials (carbonates and chlorides as well Ag20 is also 

When Pr or Tb compounds are to be prepared, the use of Pr6On or Tb407 (the sesquioxides are not available commercially) requires more time to obtain a clear solution (maybe 15 min or more), and additional HC1 solution may be needed, for example, to dissolve precipitated binary halides such as AgCl and T1C1. 

Larger-scale syntheses should be possible with appropriate sizes of the crucible, quartz tube, and tubular furnace. 

Large single crystals of Cs2NaRECl6- and Cs2NaREBr6-type compounds can be grown by a Bridgman technique.8-11 

Thermally induced phase transitions are found for Rb2NaTmCl6 (T - K)s and Cs2LiLuCl6 (6L - K - 6L)ls as well as for others. In general, higher temperatures favor structures with more face-sharing octahedra, i.e., with larger molar volumes. 

Four different crystal structure types are known for elpasolites depending on the composition and the intensive variables (temperature, pressure). A is a cubic face-centered K2NaAlF6 type, the elpasolite (there is also a lower symmetry variety, T, which can be indexed tetragonally ) with [BXg] and [REXg] octa-hedra sharing common corners, and B and RE occupying the octahedral interstices alternately between layers of composition AX3 with the stacking sequence ABCABC.  

Starting materials of course have to be replaced by bromides, hydrochloric acid by hydrobromic acid, and HCl gas by HBr gas, which is also obtainable in steel cylinders or lecture bottles. 

---