Abstract
The dielectric properties of doped quantum paraelectrics are studied within the framework of the transverse Ising model, whereby different pseudo-spins represent different unit cells. The temperature dependence of the dielectric susceptibility is similar to that of pure quantum paraelectrics when the impurity concentration is low, but has a peak like that of ferroelectrics when the impurity concentration is high enough. The effects of external electric fields on the dielectric response are investigated. Good agreement between the theoretical results and experimental observations is obtained.