Pyroelectric performances of relaxor‐based ferroelectric single crystals and related infrared detectors

Abstract

AbstractWe report in this paper our discovery of remarkably excellent pyroelectric performances in the widely investigated, but still not well understood, relaxor‐based ferroelectric single‐crystalline materials of the solid solution system of Pb(B1, B2)O3 (B1: Mg2+, In3+…, B2: Nb5+, Ta5+…) and PbTiO3, which have already been considered as next‐generation piezoelectric materials with superhigh piezoelectric effect. Values of pyroelectric coefficient as high as 17.2 × 10−4 C/m2 K and of figure of merit for detectivity of 40.2 × 10−5 Pa−1/2 can be produced in the poled crystals specifically in the crystallographic direction along the spontaneous polarization, i.e., the <111> direction in the rhombohedral phase. They show great potential as novel pyroelectric materials for wide applications in infrared (IR) detectors and thermal imagers. Commercialized IR detector prototypes have also been fabricated with the specific detectivity of 1.07 × 109 cm Hz1/2 W−1, which nearly doubles that of conventional LiTaO3 single‐crystal‐based commercialized IR detectors with similar detection mode. The relations among crystal composition, iron doping, orientation, phase structure, domain configuration, and pyroelectric property, as well as between thermal parameters and dielectric properties will also be presented here. They address the physics behind and the IR‐sensor application using the strong pyroelectric effect of this complicated but promising family of pyroelectric materials. Examples are given for Pb(Mg1/3Nb2/3)O3‐PbTiO3 (PMNT) and ternary Pb(In1/2Nb1/2)O3‐Pb(Mg1/3Nb2/3)O3‐PbTiO3 (PIMNT) systems.