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

Nanocrystalline calcium and lanthanum modified lead titanate (PCLT) powder was prepared by a sol-gel process followed by annealing at 850 degrees C. 0 -3 nanocomposite thin films of PCLT powder dispersed in a vinylidene fluori de/trifluoroethylene (P(VDF-TrFE)) copolymer matrix were fabricated on glas s substrates using the spin-coating technique. The permittivity, pyroelectr ic coefficient, specific heat and pyroelectric figures-of-merit were measur ed as functions of the volume fraction (phi) of ceramic for phi up to 0.16. Single-element pyroelectric sensors with PCLT/P(VDF-TrFE) nanocomposites a s the sensing elements were fabricated and characterized. The voltage and c urrent 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 th e piezoelectric coefficients have opposite signs, the poled composite has h igh pyroelectric but low piezoelectric activity, thereby reducing the vibra tion-induced electrical noise in pyroelectric sensor applications.