Dielectric properties and structural defects in BaTi_1−xSn_xO₃ ceramics

As a function of Sn doping concentration x, dielectric properties and X-ray diffraction measurements were carried out on BaTi_1-xSn_xO₃ (BTS_x) ceramics fabricated by the solid-state reaction route. Positron annihilation lifetime spectroscopy and coincident Doppler-broadening spectroscopy were also measured for the evaluation of defects in the BTS_x ceramics. Dielectric properties measurement reveals that the permittivity of BTS_x ceramic gradually increases with increasing Sn dopant content for x≤3%, and then decreases. This change of permittivity is found to agree well with the relative defect concentration estimated using two positron annihilation techniques. The S-W plot indicates that the defect species do not change with Sn doping. The variation correlations between defects and dielectric properties further proves that BTS_x ceramics with the higher relative defect concentration present a lower permittivity.