Crystallization and dielectric properties of oxyfluoride aluminosilicate glasses added with Na2O

Mineralizers can efficiently promote the transition of barium aluminosilicate (BaAl 2 Si 2 O 8 , BAS) from hexacelsian to celsian (H-M). However, the detailed mechanism regarding the phase transformation of BAS is still unclear, especially in different glass systems. Herein we systematically studied the crystallization behaviors of SiO 2 -Al 2 O 3 -BaF 2 glass in supercooled oxyfluoride aluminosilicate liquids with increasing Na 2 O concentration, and the influence of crystal phases precipitated from the precursor glass on the dielectric properties of oxyfluoride aluminosilicate glass ceramics was analyzed. We observed that the high addition of Na 2 O promoted no transformation of H-M, but resulted in the precipitation of second phases (e.g., NaAlSi 2 O 6 , Ba 3 AlF 9 ). Our results provide guidance for designing glass ceramics containing celsian (Monoclinic BAS) nanocrystals with superior thermodynamically stable and dielectric characters.