Preparation, dielectric and ferroelectric properties of Pb5Ge3O11 and Pb5Ge2.85Si0.15O11 thin films fabricated by sol–gel process

Lead germanate–silicate (Pb5Ge2.85Si0.15O11) ferroelectric thin films were successfully fabricated on Pt/Ti/SiO2/(100)Si substrates by the sol–gel process. The thin films were fabricated by multi-coating at preheating temperatures of 350 and 450 °C. After annealing the thin films at 600 °C, the films exhibited c-axis preferred orientation. The degree of c-axis preferred orientation of the thin films preheated at 350 °C was higher than that of films preheated at 450 °C. Grain growth was influenced by the annealing time. The thin films exhibited a well-saturated ferroelectric P–E hysteresis loop when preheated at 350 °C and annealed at 600 °C for 1.5 h. The values of the remanent polarization (Pr) and the coercive field (Ec) were approximately 2.1 μC/cm2 and 100 kV/cm, respectively.