As sintering temperature increases, the Curie temperature of each sample increases. The Curie temperature of ceramics is 110 ◦C, 119 ◦C and 122 ◦C corresponding to the sintering tempera-ture of 1200 ◦C, 1300 ◦C and 1400 ◦C respectively.
It is also observed that all the samples show no frequency dispersion of permittivity
near the maximal dielectric constant.
The dielectric constant at room temperature is nearly 1000, corresponding to all the different grain size.
The results obtained from Fig. 6 and Table 1 for the ceramics illustrate that the permittivity at room temperature is not sensitive to the grain size.