Structural and Piezoelectric Properties of (Na1−xKx)NbO3 Platelets and Their Application for Piezoelectric Nanogenerator

(Na1-xKx)NbO3 (NKN) platelets synthesized at 600 degrees C for 12 h have an Amm2 orthorhombic structure. However, the structure of NKN platelets synthesized at 500 degrees C is a mixture of R3m rhombohedral and Amm2 orthorhombic structures. The formation of a rhombohedral structure is attributed to the presence of OH- and H2O defects in the NKN platelets. The piezoelectric strain constant (d(33)) of NKN platelets synthesized at 600 degrees C for 12 h is 100 pmV(-1), whereas that of NKN plate-lets synthesized at 500 degrees C is lesser (50 pmV(-1)) due to the presence of these defects. Piezoelectric nanogenerators (PNGs) are fabricated using composites consisting of NKN platelets and polydimethylsiloxane. A large output voltage of 25 V and output current of 2.7 mu A were obtained for the PNG with NKN platelets synthesized at 600 degrees C for 6 h. This PNG shows a high output electrical energy of 3.0 mu W at an external load of 5.1 M Omega.