PCLT/P(VDF-TrFE) 0–3 nanocomposite thin films for pyroelectric applications

Abstract
Nanocrystalline calcium and lanthanum modified lead titanate (PCLT) powder was prepared by a sol-gel process followed by annealing at 850°C. 0–3 nanocomposite thin films of PCLT powder dispersed in a vinylidene fluoride /trifluoroethylene (P(VDF-TrFE)) copolymer matrix were fabricated on glass substrates using the spin-coating technique. The permittivity, pyroelectric coefficient, specific heat and pyroelectric figures-of-merit were measured as functions of the volume fraction (φ) of ceramic for φ up to 0.16. Single-element pyroelectric sensors with PCLT/P(VDF-TrFE) nanocomposites as the sensing elements were fabricated and characterized. The voltage and current responsivities Rv and Ri of the sensors were measured as functions of frequency and found to agree well with the calculated values. Since the pyroelectric coefficients of PCLT and P(VDF-TrFE) have like signs while the piezoelectric coefficients have opposite signs, the poled composite has high pyroelectric but low piezoelectric activity, thereby reducing the vibration-induced electrical noise in pyroelectric sensor applications.