Optical, piezoelectric, leakage current and polarization fatigue studies of NBT-KNN ceramics near MPB

ABSTRACT

Lead-free (1-x)Na_0.5Bi_0.5TiO₃-xK_0.5Na_0.5NbO₃/(1-x)NBT-xKNN solid solutions (x = 0.05, 0.06, 0.07, 0.08) near morphotropic phase boundary (MPB) were investigated for their optical, piezoelectric, polarization fatigue and leakage current properties. Optical band gap of all the ceramics was found to be ∼3 eV. The x = 0.07 composition exhibited large piezoelectric and electromechanical coupling coefficient, small leakage current density of ∼1.04 × 10⁻⁶ A/cm² at 40 kV/cm. The bipolar fatigue behavior carried out by the remnant polarization vs. number of cycles (up to 10⁹). These findings confirmed the existence of MPB in x = 0.07 composition and its potentiality for memory and actuator applications.

KEYWORDS:

• Optical
• piezoelectric
• leakage current
• fatigue

Funding

Ms. Swain acknowledges Department of Science & Technology, India, for fellowship grants under INSPIRE scheme with sanction order number DST/INSPIRE FELLOWSHIP/2010/ [276] during her research work.