Mechanism of local stress field enhanced pyroelectric performance of PNZST:AlN composite ceramics

Abstract

In this work, composite ceramics (1–<i>x</i>)Pb_0.99Nb_0.02[(Zr_0.57Sn_0.43)_0.94Ti_0.06]_0.98O₃:<i>x</i>AlN (abbreviated (1–<i>x</i>)PNZST:<i>x</i>AlN, <i>x</i> = 0, 0.1, 0.2, 0.3 and 0.4) are prepared by a two-step solid phase synthesis method. The crystal structures, micromorphologies, domain structure evolutions, ferroelectric, dielectric and pyroelectric properties of those composite ceramics are systematically investigated. The results show that the difference in thermal expansion coefficient between PNZST and AlN creates compressive stresses in the PNZST matrix when cooling down from the sintering temperature, then a metastable ferroelectric (FE) phase is induced in the anti-FE matrix by the AlN component-induced internal stress, and in turn ferroelectric/antiferroelectric phase boundary is constructed near room temperature. As the temperature increases, the ferroelectric-to-antiferroelectric phase transition causes a larger pyroelectric current peak. In particular, the composition with <i>x</i> = 0.1 exhibits a high pyroelectric coefficient <i>p</i> = 3.3×10^–3 C⋅m^–2⋅K^–1 and figure-of-merit with current responsivity <i>F</i>_i = 3.16×10^–9 m⋅V^–1, voltage responsivity <i>F</i>_v = 0.613 m²⋅C^–1, and detectivity <i>F</i>_d = 4.4×10^–4 Pa^–1/2 around human body temperature. Moreover, the enhanced pyroelectric coefficient exists in a broad operation temperature range with a large full width at half maximums of 16.3 ℃ at 37 ℃. With the increase of AlN content, the pyroelectric peak temperature of the composite ceramic is adjustable in a wide temperature range of 37–73 ℃, showing good temperature stability.