Crystal structure and dielectric properties of ferroelectric ceramics in the BaO-Sm2O3-TiO2-Nb2O5 system

Some tungsten–bronze ferroelectrics were synthesized and characterized in the BaO-Sm2O3-TiO2-Nb2O5 system. Ba4Sm2Ti4Nb6O30 and Ba5SmTi3Nb7O30 had the tetragonal filled tungsten–bronze structure; while Ba3Sm3Ti5Nb5O30 consisted of the orthorhombic tungsten–bronze major phase and the BaTi4O9 secondary phase. The present dielectric ceramics exhibited relaxor behavior with the maximum temperatures around 185, 285 and 130 °C for Ba3Sm3Ti5Nb5O30, Ba4Sm2Ti4Nb6O30 and Ba5SmTi3Nb7O30, respectively. Moreover, Ba3Sm3Ti5Nb5O30 exhibited a second possible phase transition around 93 °C.