Effect of polyvinylpyrrolidone on the formation of perovskite phase and rosette-like structure in sol-gel–derived PLZT films

Poly-vinylpyrrolidones (PVP) with different molecular weights were used to modify the sol-gel solutions for preparing Pb_0.91La_0.09(Zr_0.65,Ti_0.35)_0.9775O₃ (PLZT, 9/65/35) thin films. The crystallization behavior and microstructural development of the PLZT films with and without PVP addition were investigated. It was found that the addition of PVP significantly improved perovskite phase formation of the PLZT films, but the films exhibited rosette-like morphology. Further study on the PLZT films and the gel particles showed that a premature nucleation of PbO grains in the PVP modified sol-gel solution induced the Pb-rich domains in the films, which accelerated the growth of the grains and thus led to the rosette-like structure. In addition, the electrical and optical properties of the PLZT films with rosette-like structure were also studied and discussed.