Abstract: A new liquid source using water as a solvent was studied to prepare Ba_0.5Sr_0.5TiO₃ (BST) thin films by Sol-Gel
technique. DTA/TGA methods were employed to analyze this water-based BST liquid source gel. XRD results show that the film exhibits a completely
pure perovskite phase. SEM photographs show that the thickness of the films is homogeneous, and the grain size of the thin films annealed at 650℃
for 20min is about 200nm. It is found that the thickness of the film plays an important role in the dielectric properties of the BST films. The BST films
of one layer with the thickness of 1250A have better dielectric properties than those of the multilayers. The dielectric constant and dielectric loss for single
layer BST films are 330 and 0.043 at 1kHz, respectively.

Key words: perovskite, dielectric constant, dielectric loss, sol-gel