Preparation, characterization and dielectric properties of Ba5LnZnTa9O30 (Ln=La, Sm) ceramics

Ba5LnZnTa9O30 (Ln=La, Sm) ceramics were prepared by high temperature solid-state reaction route. The samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), and differential scanning calorimetry (DSC) methods. They belong to paraelectric phase of filled tetragonal TB structure at room temperature with unit cell a=12.5909(4) Å, c=3.9622(2) Å for Ba5LaZnTa9O30; and a=12.5777(4) Å, c=3.9544(2) Å for Ba5SmZnTa9O30. At 1 MHz, Ba5LaZnTa9O30 has high dielectric constants of 89 with low dielectric loss 0.0067, and temperature coefficients of the dielectric constant (τε) −811 ppm °C−1; Ba5LaZnTa9O30 has dielectric constants of 74 with low dielectric loss 0.0035, and τε −474 ppm °C−1.