Optimized physical properties of [001]-textured (Na, K)NbO-based lead-free piezoceramics for high power piezoelectric energy harvesters

The output power of piezoelectric energy harvesters is influenced by the k p and d 33 × g 33 of the piezoceramics. The untextured 0.96(Na 0.5 K 0.5 )(Nb 1− x Sb x )O 3 -0.01CaZrO 3 -0.03(Bi 0.5 Ag 0.5 )ZrO 3 [NK(N 1− x S x )-CZ-BAZ] exhibited a low k p and d 33 × g 33 owing to its small d 33 and large T 33 / 0 . The [001]-textured x = 0.01 composition exhibited an enhanced k p (0.73) and d 33 × g 33 (32.2 × 10 −12 m 2 N −1 ) owing to the increased d 33 and decreased T 33 / 0 . The domain of the textured NK(N 1− x S x )-CZ-BAZ changed from microdomains to nanodomains and polar nanoregions with an increasing x , and the altered domain structure affected the piezoelectric properties of the samples. The harvester fabricated using the [001]-textured x = 0.01 composition exhibited high power (2.7 mW) and a large power density (6.72 mW cm −3 ), which is similar to the largest power density obtained from harvesters fabricated using NKN-related ceramics. Therefore, the [001]-textured NK(N 0.99 S 0.01 )-CZ-BAZ is a promising option for application in harvesters, and the [001]-texturing technique proves to be an efficient method for developing piezoceramics for use in harvesters. The [001]-textured 0.96NK(N 0.99 S 0.01 )-0.01CZ-0.03BAZ piezoceramic has large k p and d 33 × g 33 values; therefore, the piezoelectric energy harvester fabricated using this piezoceramic exhibits a large power density.