In order to investigate the effect of A-site homovalent and heterovalent substitution on phase transition in barium titanium zirconium oxide (Ba(Ti0.7Zr0.3)O3), dielectric studies were performed on ceramics of Ba1−xAx(Ti0.7Zr0.3)O3 and Ba1-xA'2x/3 x/3(Ti0.7Zr0.3)O3 compositions (A=Ca, Sr; A′=Y, La, Bi). A preliminary X-ray powder diffraction study has allowed us to determine the limits of solid solution for each composition. A relaxor behaviour appears whatever the value of x in the solid solution domains. The corresponding relaxor characteristics were determined and discussed according to the substituted cation in the twelve coordination number (12-C.N.) crystallographic site. Such new materials are of interest for environmental-friendly applications.
