Crystallization and Dielectric Properties of Transparent Na₂O-Nb₂O₅-SiO₂Based Glass-Ceramics

Na 2 O-Nb 2 O 5 -SiO 2 based glass-ceramics with and without ZrO 2 /TiO 2 were prepared by controlled crystallization, and their crystallization properties under different heat-treatment temperatures were characterized by differential scanning calorimetry, X-Ray Diffraction (XRD) and morphology observation. The XRD results indicated the presence of NaNbO 3 with perovskite structure as the major crystalline phase. The introduction of ZrO 2 contributed to the stabilization of the Na 2 O-Nb 2 O 5 -SiO 2 basic glass, and thus improved their crystallization. Moreover, changes of the dielectric constant of the glass-ceramics with the frequency and measuring temperature were mainly studied. In details, the maximum dielectric constant reached 136.9 (@1000 KHz, 25°C), and the rate of change with temperature is as small as about −0.0302/°C. The crystalline glass remains transparent in the range of 400–800 nm, and the transmittance is above 70% for the 2 mm thick sample.