Pyroelectric properties of ZnO-based nanostructured polycrystalline ceramics

Pyroelectric materials take the most important role in pyroelectric infrared detectors. A high temperature above 550°C is required to obtain the traditional pyroelectric films such as PZT, BST, etc., which would hold back the realization of integration of pyroelectric thin film monolithic uncooled focal plane array (UFPA). Zinc oxide (ZnO) has been studied widely in recent years because of its excellent semiconducting, optical, piezoelectric and pyroelectric multiple properties. All these imply its potential applications in photo-catalysis, composite materials, dye-sensitized solar cells, sensors, as well as in UFPA applications. In the wurtzite structure of ZnO, it is easy to replace Zn by doping other metal elements such as Al, Ga, In, Sn, Cr, Mg, etc. for tailoring its properties. Thus an ideal preparation method is demanded to easily control the particle size, size distribution, crystallinity and morphology. On the other hand, the structureperformance relationship of ZnO in pyroelectric applications is still not clear. In the present work, we developed a surfactant-assisted complex sol-gel method, which allows easily control of the particle size, size distribution, crystallinity, morphology and doping of ZnO nanoparticles. Two types of ZnO nanoparticles including pure ZnO and magnesium doped ZnO were prepared for our investigation. Their detailed morphology, structural, optical properties would be presented. Pure wurtzite structure was obtained after 500°C calcinations for the sample with the Mg concentration in MgxZn1-xO below 10 at%. Well dispersed ZnO-based nanoparticles with uniform size distribution were obtained using PEG 2000 as a surfactant. The as-obtained ZnO-based nanoparticles were also sintered for pyroelectric property test. Their pyroelectric properties were compared in order to reveal its possible applications as target materials for pyroelectric films preparation in infrared detector arrays.