High permittivity and low dielectric loss of the (Ca0.9Sr0.1)1-xLa2x/3Cu3Ti4O12 ceramics

In this work, we have systematically studied the effects of La3+/Sr2+ dopants on the crystal structure, microstructure, dielectric response and electrical properties of (Ca0.9Sr0.1)(1-x)La2x/3Cu3Ti4O12 (x = 0, 0.025, 0.05 and 0.075) ceramics. XRD results show that the lattice parameter increases with the increase in the La3+ content. SEM micrographs illustrate that a small amount added of La3+ can reduce the grain size of CCTO during sintering. With increasing La3+ content, the grains grow larger. Dielectric measurements indicated that all doped samples synthesized by the solid-state reaction exhibit giant dielectric constants e'>104 over a large frequency range (10 Hz to 1 MHz) and at any temperature below 600 K. In particular, the ceramic with x = 0.05 exhibits a colossal dielectric permittivity similar to 5.49 x 10(4); which increases by about 50% compared to that of the undoped ceramic. In addition, the doped ceramic also presents a low dielectric loss similar to 0.08 at 20 degrees C and 0.6 kHz. The giant dielectric properties of these samples can be explained by the (IBLC) model.