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 R_v and R_i 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.