Synthesis of filmy ZrF4-BaF2 glasses by fluorination of amorphous oxide gels

Filmy gels ofxZrO2-(100−x)BaO compositions (x=100, 75, 60, 50 and 40) in mol% were prepared by a sol-gel process using zirconiumn-butoxide and bariumn-butoxide as starting materials. Dried gels of x=100, 75 and 60 were amorphous, while those of x=50 and 40 contained appreciable amounts of crystalline precipitates. The dried gels of x=100, 75 and 60 were fluorinated at 200 ∼ 300 °C using an HF or NF3 gas. Fluorination of the x=60 dried gel by NF3 at 250 °C gave a filmy but monolithic 60ZrF4·40BaF2 glass. The obtained glass was characterized by X-ray diffraction, infra-red absorption, DTA and ESR. The X-ray halo pattern, IR absorption spectrum, glass-transition temperature and crystallization temperature of the glass coincided with those of a 60ZrF4·40BaF2 glass prepared by a conventional melting method.