Effects of Sr-substitution on structure, dielectric, ferroelectric and magnetic properties of (SrxBa1-x)4Sm2Fe2Nb8O30 ceramics

(SrxBa1-x)4Sm2Fe2Nb8O30 (x = 0, 0.1, 0.2, 0.3, 0.4) ceramics with tetragonal bronze structure were prepared by the standard solid-state method. With the increase of x, (SrxBa1-x)4Sm2Fe2Nb8O30 ceramics transform from ferroelectric to paraelectric. The composition x = 0 shows first-order ferroelectric transition with Tc above room temperature. The other compositions exhibit broad dielectric peaks with frequency dispersion, indicating a relaxor ferroelectric transition. Saturated P-E hysteresis loops and obvious peaks in the charging current-field (J-E) curves are observed at room temperature for x = 0 and 0.1 while paraelectric characteristics are detected for the others. Magnetic hysteresis loops are obtained for all the compositions and the remanent moment increases monotonously from 0.14 emu/g to 1.21 emu/g with the increasing concentration of Sr. All the results are expected to provide valuable guidance for searching new multiferroic tungsten bronze ceramics.