Strontium Doped K_0.5Na_0.5NbO₃ Based Piezoceramics

Abstract

The effect of strontium doping in K _0.5 Na _0.5 NbO ₃ (KNN) ceramics in the amount of 0.5, 2, 5 and 10 atom % is studied. With increasing dopant content the orthorhombic distortion of the perovskite solid solution is markedly reduced. The density of stoichiometric KNN sintered at 1115°C is 94.4% of TD, doping with 0.5% Sr leads to a 2% higher density, but with higher amounts of Sr the density decreases. The values of ϵ and d ₃₃ for the undoped KNN ceramics are 450 and 80 pC/N, respectively. Sr—doping causes an increase in the dielectric constant, from 500 for KNN-0.5% Sr to 1650 for KNN-5% Sr and a decrease in the d ₃₃ constant from 95 to 50 pC/N.

Keywords:

• Lead-free piezoelectrics
• niobates
• KNN

Acknowledgments

The authors wish to thank Ms. Jana Cilensek and Mr. Silvo Drnovsek for help in the experimental work. The Ministry of Education, Science and Sports of Republic of Slovenia and the European Union (LEAF project, G5RD-CT-2001-00431) are gratefully acknowledged for financial support.

Notes

*KNN-10%Sr contains a secondary phase, therefore the fraction of the TD could not be determined.