Structural, dielectric and magnetic properties have been investigated for Ba 3 SrLn 2 Fe 2 Nb 8 O 30 (Ln=La, Nd, Sm) ceramics. The single phase tetragonal filled tungsten bronze structure in space group P4/mbm is obtained for Ba 3 SrLa 2 Fe 2 Nb 8 O 30 , while such tungsten bronze major phase is determined together with minor amount of secondary phases in Ba 3 SrNd 2 Fe 2 Nb 8 O 30 and Ba 3 SrSm 2 Fe 2 Nb 8 O 30. The saturated magnetic hysteresis loops with enhanced M r are obtained in the present ceramics at room temperature comparing to the Ba 4 Ln 2 Fe 2 Nb 8 O 30 (Ln=La, Nd, Sm) ceramics. Meanwhile, the typical relaxor behaviors are determined: a broad dielectric peak with strong frequency dispersion and the peak temperature following well with the Vogel-Fulcher relationship.

In the present work, the structural, dielectric and relaxor ferroelectric properties were investigated for Ba3Ln3Ti5Nb5O30 (Ln = La, Nd, Sm) ceramics. The filled tungsten bronze phase with space group P4/mbm was confirmed for all compositions, while a small amount of secondary phase was detected in Ba3Nd3Ti5Nb5O30 and Ba3Sm3Ti5Nb5O30. The typical relaxor ferroelectric behaviors were observed: a broad peak of dielectric constant shifting to higher temperatures and decreasing its magnitude with increasing frequency and the frequency dispersion obeying the Vogel-Fulcher relationship. The P-E (polarization-electric field) hysteresis loops were obtained for Ba3Ln3Ti5Nb5O30 (Ln = La, Nd, Sm) ceramics at low temperatures. The nanoscale ferroelectric 180° domains with strip-like shape were observed in the paraelectric matrix at room temperature, where the commensurate structural modulations were determined in the domains and incommensurate ones were determined in the matrix. The significant differences were determined between the present ceramics and Ba4Ln2Ti4Nb6O30 and Ba5LnTi3Nb7O30 because of the different distribution patterns of A1 and A2 cations.