Low-firing Pb(Mg1/3Nb2/3)O3-PbTiO 3-Pb5Ge2SiO11 compositions for thick film capacitor applications

Commercial ferroelectric thick films have been developed with high dielectric constants for capacitor applications. However, these compositions typically do not densify well in thick film form at characteristic firing temperatures (850~900°C), and thus require encapsulants to provide environmental stability. In this paper, ferroelectric compositions that can be fired at low temperatures with useful dielectric properties for thick film application are presented based on the combination of Pb(Mg_1/3Nb_2/3)O₃ (PMN)-PbTiO₃ (PT) with Pb₅Ge₂SiO ₁₁ (PGS). The PGS melts at ≈724°C, and causes liquid phase sintering of the PMN-PT at low temperatures. Thick film samples of PMN-PT with 30 weight percent PGS and 5 weight percent PbO additions densify to closed porosity fired at 850°C for 10 minutes with a room temperature 1 KHz dielectric constant greater than 1500 and a dissipation factor less than 6%. Preliminary results indicate that these compositions are compatible with a commercial silver thick film conductor paste (DuPont 6160)