Pyroelectric properties of PZT/PMNZTU composite thick films

Lead zirconate titanate/uranium doped lead magnesium niobate - lead zirconate titanate (PZT/PMNZTU) composite thick films have been fabricated on silicon substrates at 710°C using a composite sol gel technique. A slurry, made up of PMNZTU powder and PZT sol, was spun onto a silicon substrate and fired to yield a porous skeletal ceramic structure. Subsequent sol infiltration and pyrolysis was used to modify the density of the films prior to final sintering at 710°C. Pyroelectric and dielectric properties have been measured as a function of sol infiltration. The pyroelectric coefficients (p_max = 2.41 × 10^-4 Cm^-2 K^-1) of the composite thick films were found to be comparable to the tape cast and monolithic ceramics of similar composition (2.8 and 3.0 × 10^-4 Cm^-2 K^-1 respectively). Maximum figures of merit (F _v = 2.23 × 10^-2 m² C^-1, F _D = 0.89 × 10^-5 Pa^-1/2), calculated using the electrical properties of the thick films, can be compared with those of screen printed thick films (F_v = 2.7-3.9 × 10^-2 m² C^-1, F_D = 0.8-1.1 × 10^-5 Pa^-1/2) processed at temperatures of ca 1100°C. The ability to directly integrate thick pyroelectric films onto substrates at temperatures as low as 710°C, while maintaining competitive figures-of-merit is of considerable interest for future device applications.