Dielectric Properties of Poly- and Single-Crystalline BaTi_2O_5

摘要

Non-oriented and (010) oriented poly-crystalline BaTi_2O_5 (BT_2) was prepared by hot-pressing and arc-melting, respectively. The dielectric properties of poly-crystalline BT2 were compared with those of single-crystalline BT_2 prepared by a floating zone method. The maximum permittivity of (010) oriented poly-crystalline BT_2 was 2000 at 720 K, whereas that of single-crystalline BT_2 was 6000 at the Curie temperature, T_c (750 K). The permittivity of non-oriented poly-crystalline BT_2 was 30 to 300, having a small peak at 720 K. The tan delta 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 BT_2 had almost same values, which were one order higher than that of non-oriented poly-crystalline BT_2 and (001) oriented single-crystalline BT_2.