Piezo and pyroelectricity in spark plasma sintered potassium sodium niobate (KNN) ceramics
Toufique Morshed, Ehtsham Ul Haq, Christophe Silien, Syed A. M. Tofail, Md. Abdullah Zubair, Md. Fokhrul Islam
Abstract
We report fabrication and piezo- and pyroelectric characterizations of spark plasma sintered (SPS) lead-free K <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> Na <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0.5</sub> NbO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (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 <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">33</sub> and pyroelectric coefficient of poled KNN ceramic are 94 pC/N and 22.84 μCm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-2</sup> K <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> , 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.