Structural and Piezoelectric Properties of (Na_1−xK_x)NbO₃ Platelets and Their Application for Piezoelectric Nanogenerator

Abstract

(Na1−xKx)NbO3 (NKN) platelets synthesized at 600°C for 12 h have an Amm2 orthorhombic structure. However, the structure of NKN platelets synthesized at 500°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 (d33) of NKN platelets synthesized at 600°C for 12 h is 100 pmV−1, whereas that of NKN platelets synthesized at 500°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 μA were obtained for the PNG with NKN platelets synthesized at 600°C for 6 h. This PNG shows a high output electrical energy of 3.0 μW at an external load of 5.1 MΩ.

Nanogenerator-induced synaptic plasticity and metaplasticity of bio-realistic artificial synapses

“…The piezoelectric NG was fabricated using NKN platelets and was operated manually (by finger tapping). 37 Figure 2b shows the output voltages generated by the NKN NG after negative rectification. The red and blue arrows in the inset of Figure 2b indicate the output voltages generated by pressing and releasing the NG, respectively.…”