Structural and dielectric properties of Ba(ZrxTi1-x)O3 thin films prepared by the sol-gel process

The Ba(ZrxTi1-x)O-3 (BZT) thin films were prepared by deposition of relevant materials on LaNiO3-coated silicon substrates by the sol-gel process. The films thus prepared show a (100) preferred orientation in structure and vary with zirconium content. With the addition of Zr, the grain sizes of films were found to decrease, whereas their microstructure became dense. The changes in the films' grain sizes and microstructure were attributed to the addition of Zr to the BaTiO3 lattice. Dielectric constant measurements revealed that the thin films show a relaxor behaviour and have a diffuse phase transition characteristic when x is 0.35. The hysteresis loops of the dielectric properties of films measured at room temperature were considered to be the result of the polarization state of the domains in these films in both the ferroelectric or paraelectric state. This leads to a distribution of Curie temperatures. The highest figure of merit value, K, was found for the BZT thin film with a very low dielectric constant. This indicates that BZT films have the potential to be used as microwave tunable devices with superior performance.