Dielectric properties of poly- and single-crystalline BaTi2O5

Non-oriented and (010) oriented poly-crystalline BaTi2O5 (BT2) was prepared by hot-pressing and arc-melting, respectively. The dielectric properties of poly-crystalline BT2 were compared with those of single-crystalline BT2 prepared by a floating zone method. The maximum permittivity of (010) oriented poly-crystal line BT2 was 2000 at 720 K, whereas that of single-crystalline BT2 was 6000 at the Curie temperature, T-c (750 K). The permittivity of non-oriented poly-crystal line BT2 was 30 to 300, having a small peak at 720 K. The tan beta of all specimens was 0.01 to 0.2 below T-c and significantly increased with increasing temperature above T-c. The electrical conductivity of (010) oriented poly- and single-crystalline BT2 had almost same values, which were one order higher than that of non-oriented poly-crystalline BT2 and (001) oriented single-crystal line BT2.