Synthesis and characterization of low softening point high Bi2O3 glasses in the K2O-B2O3-Bi2O3 system

► Synthesis of low softening point (< 470 °C) high Bi2O3 content (40-90 mol%) glasses. ► Study of boron anomaly phenomenon with gradual addition of Bi2O3 in the glass. ► Co-efficient of thermal expansion decreases from 153 to 109 x 10− 7 K− 1. ► Dielectric constant increases from 21 to 34 with increase in Bi2O3 content. ► Formation of metallic bismuth in the glass confirmed by the XRD and TEM analyses.