hello dear
this is well known material and all the properties are well studied .this material have high dieletric constant (more than 100) and low tangent loss (around 0.001).
you can refer some paper like "Microstructure and dielectric properties of ferroelectric barium strontium titanate ceramics prepared by hydrothermal method"
Hongyan Miao & Yaohui Zhou & Guoqiang Tan &Min Dong in J Electroceram.