Résumé
BaB2O4-NaF pseudobinary system has been found to form a simple eutectic phase diagram with the eutectic composition corresponding to 61 mol% NaF and eutectic temperature of 754°C. Complex investigation of BaB2O4-NaF system revealed primary crystallization area of new fluorine borate Ba2Na3[B3O6]2F. Concentration interval from 47.5 to 57 mol % NaF corresponds to the Ba2Na3[B3O6]2F primary crystallization area. According to DTA data new fluorine borate Ba2Na3[B3O6]2F melts congruently at 835°C. X-ray structural analysis showed that Ba2Na3[B3O6]2F crystallizes in hexagonal system, space group P63/m, a=7.346 Å, c=12.637 Å, Z=2. Its hardness is 4.5 on the Mohs scale. Absorption spectrum was measured on spectrometer Shimadzu-UV-2501-PC. Absorption edge in UV region is about 200 nm. Thus, it can be concluded that BaB2O4 – NaF system can not be considered as quasibinary. Further research of the system should be carried along its multicomponent character and the principle quadruple mutual Na,Ba,B//O,F system should be taken into consideration