Influence of heat treatment on microwave dielectric properties of erbium doped borotellurite glass ceramics

High-performance glass-ceramics are increasingly explored for their suitability in highfrequency dielectric applications, presenting a significant challenge in materials science. A primary focus has been allocated to investigating borotellurite glasses operating at frequencies below 15 MHz. Borotellurite glasses with the composition 69TeO₂-10B₂O₃- 10PbO-10ZnO-1Er₂O₃ were fabricated via the melt-quenching method. This study examines the effects of heat treatment durations (1–24 hours) on these glasses. Variations in density, molar volume, structure, and dielectric properties were attributed to changes in non-bridging oxygen bonding resulting from the heat treatments. X-ray diffraction analysis confirmed the amorphous nature of the as-quenched glass. Morphological changes due to heat treatment were analyzed using field emission scanning electron microscopy, revealing grain size variations between 0.237 and 1.509 μm. Dielectric constant and loss tangent were measured at approximately 7 GHz using a resonant method for both glass and glass-ceramic phases at different crystallization times. Heat treatment increased the crystalline volume fraction within the glass-ceramic. The resulting material demonstrated a dielectric constant up to 17.75 ± 9 % and a dielectric loss of 1.03 x 10-4 ± 17 %, indicating potential for use in microwave applications.