Fabrication of Nb-doped lead zirconate titanate thick films synthesized by sol–gel dip coating method

Modifying the lead zirconate titanate thick films by Nb⁵⁺ can thoroughly optimize the properties of the thick films in micro-electromechanical systems, sensors, and microactuators. In this article, the Nb⁵⁺ is doped in sol–gel synthesized thick films of PZT with the thickness of more than 27 µm. In order to produce the thick films, a new modified sol–gel method based on the niobium chloride precursor is applied. The lattice constants, lattice distortion, and the preferred-orientation of the films are measured by means of X-ray diffraction. The surface morphology and grain size of the films are examined by field emission scanning electron microscopy. The results demonstrated the formation of pure perovskite phase with the tetragonal lattice parameters of c_t = 4.114 Å and a_t = 4.039 Å and the average grain size of 28 nm in the sample with 2 at.% Nb. Moreover, the hysteresis loops and dielectric constants of the films are compared by electrical measurements. The results illustrated 1.23-fold increase in remanent (from 5.7 µC cm⁻² for undoped sample to 12.7 µC cm⁻² for 2 at.% Nb) and 6.65-fold increase in dielectric constant (from 275 for undoped sample to 2080 for 3 at.% Nb).