Structural and dielectric properties of Sr4Ln2Ti4Ta6O30 (Ln = Nd and Sm) ceramics

Sr4Ln2Ti4Ta6O30 (Ln = Nd, Sm) ceramics were prepared and characterized. Sr4Sm2Ti4Ta6O30 is found to be ferroelectric phase of filled tetragonal tungsten bronze (TB) structure at room temperature and undergoes diffuse type of ferroelectric–paraelectric phase transition around 30 °C, while Sr4Nd2Ti4Ta6O30 belongs to paraelectric phase of TB structure at room temperature. Sr4Sm2Ti4Ta6O30 and Sr4Nd2Ti4Ta6O30 ceramics show high dielectric constant of 220 and 225 together with dielectric loss 4.7 × 10− 3 and 1.1 × 10− 3 at 1MHz, respectively.