Porous, Functionally Gradient Pyroelectric Materials

Abstract

Properties of a new type of pyroelectric ceramic structure containing a layer of known porosity laminated between two dense layers, to form a functionally-gradient material (FGM) are reported. Combination of theoretical models for pyroelectric, dielectric and thermal properties gave a model for the pyroelectric voltage figure of merit (F V ) in good agreement with experiment, which had shown a 20% improvement for an introduced central layer porosity of 27%. Preliminary pyroelectric responsivity measurements on FGM infra-red detectors indicated even better improvement. It is postulated that this is due to the porous layer acting as a thermal barrier in the structure.

Enhanced pyroelectric properties of porous Ba0.67Sr0.33TiO3 ceramics fabricated with carbon nanotubes

“…For pyroelectric materials, porous ceramics have a lower heat capacity and dielectric constant. It has been reported that both porous PZT and BST materials have a higher figure-of-merit [9][10][11][12]. However, there are still problems with porous PZT pyroelectric materials.…”

“…However, there are still problems with porous PZT pyroelectric materials. Pores depress PZT's pyroelectric coefficient [9][10][11], and it is difficult to fully polarize porous samples because of a large leakage current arising from the pores. BST has been widely used as dielectric bolometer [3,[13][14][15], and its pyroelectric coefficient can be obtained as follows [12,15,16]:…”

Utilization of Electrolytic Manganese Residues in Production of Porous Ceramics

“…Porous ceramics have attained increasing attention for their wide range of engineering application because of their high apparent porosity, moderate surface area, and excellent acidity–alkali resistance, and some applications include separation membranes, filters, piezoelectric and pyroelectric ceramics, lightweight structural materials, biomaterials, battery separators, and solid oxide fuel cell electrodes . Nevertheless, many commercial porous ceramics are fabricated using silicon dioxide, aluminum oxide, carborundum, and mullite as raw materials, which seriously limits their large‐scale applications due to their high cost of production or complex preparation techniques.…”

Ba0.68Sr0.32TiO3/Ba0.68Sr0.32TiO3 + Mn composite with low loss and high pyroelectric coefficient

“…Whereas, the “core‐shell” structure was difficult to control. In recent years, porous pyroelectric ceramics and films were fabricated and exhibited excellent properties 4, 13–15. All of these demonstrated that changing the microstructure of ceramics was an effective way to improve the electrical properties.…”