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. The dielectric loss was measured at
the frequency of 500 kHz, and the lowest dielectric loss (0.021)was
obtained in the sample sintered at 1300 ◦C with grain size around
20m.