Fabrication of textured (K,Na)NbO3-based ceramics at low sintering temperatures by using NaNbO3 templates prepared with hydrothermal method

Abstract

Texturing is an effective approach to improve the performance of piezoelectric ceramics. The templates employed in this work were prepared using the hydrothermal method, in which plate-like hexagonal NaNbO3 (NN) particles were synthesized at 200 °C and converted to the perovskite structure through heat treatment at 550 °C. This is because the hydrothermal method represents the most promising approach to the low-cost, low pollution, and large-scale production of template particles for manufacturing textured ceramics. Textured Mn-doped (K,Na)NbO3-based piezoelectric ceramics with a vertical morphotropic phase boundary (MPB) were fabricated using the reactive template grain growth (RTGG) method. A good degree of orientation (66%) and a notable piezoelectric constant (320 pC N−1) were achieved after the addition of 10 mol% of the perovskite structure NN template and sintering at 1040 °C for 10 h. The SEM results revealed that the textured ceramics had a microstructure composed of rectangular grains that exhibited a brick wall-like alignment.