Effect of ZrO 2 addition on crystallization and properties of the glass-ceramics contained NaNbO 3 crystals

Abstract

Ferroelectric glass-ceramics containing NaNbO 3 crystals are prepared from the Na 2O–Nb 2O 5–SiO 2 system employing heat treatment process. ZrO 2 is systematically added to the glass compositions to study its effect on crystallization behavior of the glass and dielectric properties of the associated glass-ceramics. DTA trace measured from the as-quenched samples reveals shifting of the glass transition and the crystallization ranges to the higher temperature with increasing of ZrO 2 content. Then, the glass samples are subjected to heat treatment process at appropriate temperatures and times. Phase identifications through XRD analysis have shown that only the NaNbO 3 phase is devitrified in the glass-ceramics treated at 750 °C for 1 h. At 800 °C, precipitation of the secondary phase NaNb 3O 8 is additionally found but it present in only a small proportion. Crystallite size of the NaNbO 3 crystals determined from the X-ray diffracted peaks are in range 20–50 nm. The dielectric constants of the glass-ceramics measured at room temperature depend on the volume fraction of NaNbO 3 which varied with the ZrO 2 content.