Study on Defect Complexes in High-k Sr and Zr Co-doped BaTiO3 Ceramics

In order to investigate the evidence for the formation of Sr2+-Zr4+ defect complexes in high-k Sr and Zr co-doped BaTiO3 ceramics, BaTiO3, (Ba0.85Sr0.15)TiO3, Ba(Ti0.8Zr0.2)O-3, and (Ba0.85Sr0.15)(Ti0.8Zr0.2)O-3 (BS15TZ20) ceramics were prepared using a mixed oxide method. The Y5V-type BS15TZ20 shows a high-k diffuse phase transition behavior (epsilon'(m) = 8000) and its Curie peak occurs near room temperature. The evolution in crystal structure and in dielectric property for the four samples gives four evidences for the formation of Sr2+-Zr4+ defect complexes in BS15TZ20. The splitting of the 720 cm(-1) Raman band does not relate to Sr2+-Zr4+ defect complexes, but to a multiphonon (A(1) (TO2) + A(1) (TO3)).