Electrical properties and degradation behaviour of BNT-BT-LN ceramics

Abstract

In this paper, phase composition, microstructure, dielectric, ferroelectric and failure behaviour of lead-free (1-x)(Bi0.5Na0.5TiO3-BaTiO3)-xLiNbO3 (BNT-BT-LN, x = 0.01, 0.03, 0.05, 0.07 and 0.10) ceramics were investigated. The introduction of LiNbO3 did not change the original perovskite crystal structure of the ceramics with the coexistence of rhombohedral and tetragonal phases. However, with the increase of x (i.e. LN content), the characteristic split XRD peaks became more and more symmetrical. It was observed by scanning electron microscopy that the growth of ceramic grain size was promoted with the increase of LN content. The dielectric temperature stability was also effectively improved with addition of LN. When x = 0.07, the temperature coefficient of capacitance (TCC150 °C) was below ±15% in temperature range of 35-400 °C with moderate permittivity ("r150 °C = 2050) and low dielectric loss (tan _150 °C = 0.005). The RC time constant of this sample was higher than 19.3 s at temperatures up to 245 °C. The mean time to failure (TTF) empirical formula for the BNT-BT-LN dielectrics was established through highly accelerated life test. As predicted, the TTF could reach 4.67 × 106 h under the applied electric field of 7 kV/mm at room temperature.

Keywords

• bnt-bt
• linbo3
• dielectric temperature stability
• ferroelectric properties
• mean time to failure