Effects of Na₂O additions on the thermal and optical properties of BaO-ZnO-B₂O₃-SiO₂ glass powders prepared by spray pyrolysis

Fine-sized BaO-ZnO-B₂O₃-SiO₂ (BZBS) glass powders doped with various amount of Na2O were directly prepared by spray pyrolysis at a temperature of 1400°C. The BZBS glass powders prepared with low amounts Of Na₂O below 5.7wt.% of the product had a glass structure with amorphous phases. The glass transition temperature (T _g) of the BZBS glass powders was changed from 517.3 to 468 °C when the amount of Na₂O added to the product was changed from O to 5.7 wt.%. Melting of the glass powders with 1.9 wt.% Na₂O occurred at a temperature of 56O °C. On the other hand, melting of the glass powders with 3.8 and 5.7 wt.% Na₂O occurred at temperatures of 540 and 520 °C, respectively. The dielectric layers formed from the glass powders with an amount of Na₂O added below 5.7 wt.% of the product had high transparencies, above 80%, at a firing temperature of 580 °C. The addition of Na₂O to the glass powders improved the transparencies of the dielectric layers at low firing temperatures.