Preparation and piezoelectric properties of CuO-doped (Na_0.5K_0.5)NbO₃ ceramics by the citrate precursor method

摘要

A low-cost citrate so-gel route was investigated to synthesize nano-sized crystalline powders (<100 nm) of 1 mol% CuO modified (Na_0.5K_0.5)NbO₃ compositions. It was found that amorphous gels can be transformed into crystallite powders with single-phase perovskite structure when calcined at 500–600 °C for 3 h. The transmission electron microscopy observation showed that the particles are column-like and well dispersed, depending on the calcination condition. The as-pressed samples exhibit improved densification behavior and finer grain morphology after sintering. Electrical properties of the samples sintered at 1,060 °C are as follows: dielectric constant ε _r = 605, piezoelectric constant d ₃₃ ~ 117 pC/N, planar electromechanical coupling factor k _p ~ 0.38 and mechanical quality factor Q _m ~ 725.