Electrical Properties of Fresnoite Ba_2TiSi_2O_8 Using Impedance Spectroscopy

摘要

Fresnoite with composition Ba_2TiSi_2O_8 (B_2TS_2) was first found in 1965, adopting a non-centrosymmetric structure. It also reported to crystallize in a tetragonal unit cell with a=8.52 A and c=5.210 A leading to some possible application as hydrophone, transducer and second harmonic generation and low temperature co-fired ceramics (LTCC). B2TS2 were synthesized by conventional solid state reaction. Phase-pure B_2TS_2 was obtained after heating the pellets at a final sintering temperature of 1230°C in air at 92 h. Study found that Fresnoite B_2TS_2 is a type of materials which are not ferroelectric and instead show perfect dielectric insulator behaviour with resistance >10~6Ωcm at temperatures below 750°C and also shows nonideal debye respone. The activation energy for conduction of B_2TS_2 samples is very high, indicating that these materials are highly insulating.