The effect of CuO and NiO doping on dielectric and ferroelectric properties of Na_0.5Bi_0.5TiO₃ lead-free ceramics

Abstract

In the present work, lead-free piezoelectric ceramics (Na_0.5Bi_0.5)TiO₃ –xCuO–yNiO (for x = 0.0, 0.02, 0.04 and 0.06) have been prepared by a conventional solid-state reaction method. An investigation of CuO and NiO doping in bismuth sodium titanate (BNT) and a study of the structure, morphology, and dielectric and ferroelectric properties of the NBT–CuNi system have been conducted. Phase and microstructural analysis of the (Na_0.5Bi_0.5)TiO₃ (NBT) based ceramics has been carried out using X-ray diffraction and scanning electron microscopy (SEM) techniques. Field emission scanning electron microscopy (FE-SEM) images showed that inhibition of grain growth takes place with increasing Cu and Ni concentration. The results indicate that the co-doping of NiO and CuO is effective in improving the dielectric and ferroelectric properties of NBT ceramics. Temperature-dependent dielectric studies have also been carried out at room temperature to 400 °C at different frequencies. The NBT ceramics co-doped with x = 0.06 and y = 0.06 exhibited an excellent dielectric constant ϵ_r = 1514. The study suggests that there is enormous scope of application of such materials in the future for actuators, ultrasonic transducers and high-frequency piezoelectric devices.

Keywords:

• ceramics
• X-ray diffraction
• dielectric properties
• piezoelectricity
• ferroelectric

Acknowledgements

The authors are grateful to the School of Material Science & Technology, Indian Institute of Technology, Banaras Hindu University, Varanasi, for XRD and SEM measurements. The authors also extend their thanks to Prof. R.K. Dwivedi, JIIT, Noida, India, for P–E loop measurements.

Disclosure statement

No potential conflict of interest was reported by the authors.