The ferroelectric (FE) materials are continuously attracting considerable attention due to the interesting combination of their mechanical, electrical and chemical properties and their application in microelectromechanical devices (piezoelectric transformers, motors and transducers). To be more specific, their excellent electrostrictive properties coupled with domain mobility, high Curie point and good stability make these 'new materials' important components of electroceramic devices. It is already known that the electrical behaviour of these FE materials largely depends on random elasto-electric fields connected with the diffusion of phase transition and defects distribution. The aim of this article is the exposition of phase transition dependence on Sr2+ homovalent dopant in (Pb0.70Sr0.30)(Zr0.70Ti0.30)O3 ceramics investigated by electrical methods. We demonstrate that electrical examination can be effectively used for drawing decisive applications conclusions from the grain and grain boundary parameters distribution. Modification of FE materials with isovalent ions, but with radii bigger than the original atom, significantly affect its properties, particularly the (Pb,Sr)(Zr,Ti) O3 real part of electrical permittivity shows the change of phase transition from FE to relaxor.