Piezo and pyroelectricity in spark plasma sintered potassium sodium niobate (KNN) ceramics

We report fabrication and piezo- and pyroelectric characterizations of spark plasma sintered (SPS) lead-free K 0.5 Na 0.5 NbO 3 (KNN) ceramics. SPS sintering produced dense KNN (99% of the theoretical density) at sintering temperature as low as 900°C. A significant improvement in the dielectric, piezoelectric and pyroelectric properties is observed after annealing the sample at 925°C. The measured piezoelectric coefficient d 33 and pyroelectric coefficient of poled KNN ceramic are 94 pC/N and 22.84 μCm ⁻² K ⁻¹ , respectively. These values are high enough to focus on the further enhancement of the material properties through adequate control of the phase structure of the material for lead-free energy harvesting applications.