Villiaumite Deshpande V T Acta Crystallographica 14 (1961) 794-794 Thermal expansion of sodium fluoride and sodium bromide Note: T = 254 C, rocksalt structure _database_code_amcsd 0009257 4.6726 4.6726 4.6726 90 90 90 Fm3m atom x y z Na 0 0 0 F .5 .5 .5