Electrical and Piezoelectric Properties of Lead-Free (K_0.5Na_0.5)(Nb_0.9Ta_0.1)O₃ Ceramics Prepared From Nanopowders

Abstract

There has been a growing interest in developing lead-free alternatives to replace the currently dominant lead-based piezoelectric materials due to the toxicity of lead. (K_0.5Na_0.5)NbO₃–based piezoelectrics are promising because of their relatively high Curie temperatures and piezoelectric coefficients among the lead-free piezoelectrics. In the present work, nanopowders of different particle sizes for the lead-free ceramic system (K_0.5Na_0.5)(Nb_0.9Ta_0.1)O₃ have been prepared under different milling conditions by using high energy ball milling. The effect on the particle size has been investigated by increasing the milling time at a fixed milling speed of 250 rpm. The average particle size of the milled powders as determined from the TEM analysis ranges from 6–35 nm as the milling parameter changes. These powders were sintered at 1040°C for 3 hours. X-ray Diffraction studies showed single phase perovskite structure of the ceramics formed. Without any sintering aid, more than 94% densification has been observed for these ceramic samples. The change in the microstructural properties of the ceramics with the variation of particle size of the starting powder has been examined from the SEM analysis. The electrical and piezoelectric properties of the ceramic samples have also been studied.

Keywords:

• Lead-free
• perovskite structure
• ceramics
• piezoelectric
• ball milling

Acknowledgments

The financial support from UGC of India under the Major Research Project Scheme vide No. F. 33-25/2007(SR) is gratefully acknowledged. We also acknowledge the Director, Solid State Physics Laboratory and AIIMS for providing facilities for some measurements.