Temperature-induced phase transition of PNZST ceramics near the morphotropic phase boundary for thermal-electrical energy conversion

In this work, the temperature-induced phase transition of (Pb0.99Nb0.02)[(Zr0.70Sn0.30)1-xTix]0.98O3 (PNZST) ceramics near the morphotropic phase boundary (MPB) was investigated systematically. Increasing Ti content will stabilize the ferroelectric (FE) phase and destabilize the antiferroelectric (AFE) phase in PNZST ceramics, resulting a switching from AFE to FE. When x = 0.06, the composition has an initial AFE phase and can be induced into a stable FE phase at external electric field and when x = 0.08, the composition is normal FE. With increasing temperature, the poled PNZST sample (x = 0.06 and 0.08) will experience a ferroelectric-antiferroelectric-paraelectric (FE-AFE-PE) transition. The increasing Ti content will result in higher FE-AFE transition temperature. A step “0–1” voltage signal up to 90 V and a current pulse can be achieved in a specific circuit when the poled ceramics were heated. An electric energy of 13.7 mJ/cm3 was obtained during the heating process. And when the composition is closer to the AFE/FE boundary (x = 0.06), the voltage step signal is steeper because the charge release is more intensive. The special output electrical signal makes the PNZST ceramics near the MPB with potential applications for temperature sensor, temperature-controlled switch and temperature-driven pulsed power source. The phase transition properties can be further modified by modify the compositions near the MPB to satisfy different applications.