Barrier layers formation in tin substituted calcium copper titanate CaCu3Ti4-xSnxO12 (0 ≤ x ≤ 1.0)

A few compositions in the system CaCu3Ti4-xSnxO3 (0 ≤ x ≤ 1.0) were synthesized by solid state diffusion controlled thermochemical process. Powder X-ray diffraction patterns of all the compositions show that these compositions are single phase solid solution. All the samples have cubic crystal structure similar to undoped CaCu3Ti4O12. Microstructure shows that average grain size is about 10 μm. Dielectric measurements have been carried out in the temperature and frequency range 300-450 K and 1 kHz-1 MHz, respectively. It has been shown by complex plane impedance and modulus analysis that barrier layers form at grain boundaries in these materials. These barriers impart high value of dielectric constant to the resultant ceramic. Dielectric constant, εr can be enhanced and dielectric loss (loss tangent), D can be reduced further by chemical infiltration. (author)