Electrical properties of silver nanoparticles reinforced LiTaO 3 :P(VDF-TrFE) composite films

Abstract

ABSTRACT Pyroelectric infrared Lithium tantalite [(LiTaO 3 ), LT] ceramic particles and silver nanoparticles have been incorporated into a polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE) 70/30 mol%] copolymer matrix to form composite films. The films were prepared using solvent casting method. Electrical properties such as the diel ectric constant, dielectric loss, and pyroelectric coefficient have been measured as a function of temperature. In addition, materials’ figures-of-merit have also been calculated to assess their use in infrared detectors. The results show that the fabricated silver nanoparticles incorporated lithium tantalite: polyvinylidene fluoride-trifluoroethylene composite films may have a good potential for uncooled infrared sensor applications. Key words: Pyroelectric composite, Infrared detectors, Lithium tantalite, Polyvinylidene fluoride-trifluoroethylene, Ag nanoparticles 1. INTRODUCTION A pyroelectric detector exposed to in frared radiation absorbs the radiati on and its temperature rises. The rise in the temperature changes the spontaneous polarization, and thus photocurrent is obtained. Infrared imaging devices have numerous applications, including military night vision, security surveillance, fire detection, medical diagnostics, and automotive vision enhancement, imaging systems for cars, ships, aircraft, and others. Pyroelectric infrared sensing devices have several advantages over photon infrared sensors: i.) Sensitivity over a larger spectral bandwidth; ii.) Sensitivity over a wide temperature range without the need of cooling; iii.) Low power requirements; iv.) Relatively fast response; v.) Generally low cost of materials; vi.) Detection is limited, being a passive device; vii.) Temperature range of operation can be changed in certain materials by the variation of the amount of its constituents (such as Lead zirconate titanate, Potassium titanate niobate and others); and viii) Suitable for space applications because of light weight; consuming less powe r having no bulky cooling equipment. Ferroelectric ceramic and polymer composites are a well-established alternative to conventional ferroelectrics for sensors and actuator applications because they combine the mechanical compliance and flexibility of polymer with the high piezoelectric and pyroelectric activities of electro-ceramic [1-3]. In the present work, Lithium tantalite [(LiTaO