Dielectric Properties of Poly- and Single-Crystalline BaTi<SUB>2</SUB>O<SUB>5</SUB>

Abstract

Non-oriented and (010) oriented poly-crystalline BaTi 2 O 5 (BT 2 ) was prepared by hot-pressing and arc-melting, respectively. The dielectric properties of poly-crystalline BT 2 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 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 .

Preparation of the Oriented Polycrystalline BaTi2O5 Ferroelectric Ceramics

“…Recently, the dense and single-phased BT 2 sintered bodies with a preferred growth direction along the b-axis were obtained via a solid-state reaction of BaCo 3 with Tio 2 at 1025°C in air using B 2 o 3 as the additive [11]. The permittivity of the obtained polycrystalline BT 2 was higher than that of polycrystalline BT 2 in previous research [6][7][8] but much lower than that of single-crystalline BT 2 [11,12], which was caused by the random and disordered arrangement of b-axis oriented BT 2 in the sintered bodies. as is known to all, the needle-like BT 2 single crystal could be grown from a melt along the b-axis direction [12], which indicated that polycrystalline BT 2 with b-axis orientation could be obtained by a meltingsolidification method.…”

“…as is known to all, the needle-like BT 2 single crystal could be grown from a melt along the b-axis direction [12], which indicated that polycrystalline BT 2 with b-axis orientation could be obtained by a meltingsolidification method. According to this finding, Tu et al [7] had prepared b-axis oriented, single-phased and polycrystalline BT 2 by an arc melting process; however, a large amount of cracks were found in the obtained samples, which would affect the dielectric properties.…”

“…Since BT 2 can be converted to BaTio 3 (BT) and Ba 6 Ti 17 o 40 (B 6 T 17 ) at a temperature higher than 1150°C [4], it is difficult to prepare the large-scale and dense polycrystalline BT 2 in a single phase. although the single-phased and cation-doped polycrystalline BT 2 ceramics could be prepared via a low temperature sol-gel [5,6] and solid-state reaction route [7,8], the thus-obtained ceramics exhibited low permittivity at T c , a broad dielectric curve due to an orientation deviating from the b-axis orientation [5][6][7][8][9][10], and a low relative density due to the existence of cracks [7,9] and pores [5,10]. Recently, the dense and single-phased BT 2 sintered bodies with a preferred growth direction along the b-axis were obtained via a solid-state reaction of BaCo 3 with Tio 2 at 1025°C in air using B 2 o 3 as the additive [11].…”

Nanocrystalline BaTi2O5 dielectric ceramic prepared by full crystallization from containerless solidified glass

“…The single-crystalline BaTi 2 O 5 prepared by floating zone melting shows a high Curie temperature (T C = 430-475 ℃) and a high permittivity in b-direction without lead additives [19,20]. Hence, BaTi 2 O 5 ceramic is fabricated and studied as a promising environmentally friendly material [15,[21][22][23][24]. Polycrystalline BaTi 2 O 5 ceramic was prepared by laser rapid solidification method [22].…”

Dielectric Properties of Ba<SUB>1&minus;<I>x</I></SUB>Ca<I><SUB>x</SUB></I>Ti<SUB>2</SUB>O<SUB>5</SUB> Prepared by Arc Melting

“…7) In practical applications, however, polycrystalline material is preferable to single crystalline material due to its ease of manufacturing and low cost. In a previous study, 8) we prepared (020) orientated polycrystalline BT 2 by arc melting. Substitution of foreign element has been commonly applied to improve and modify the performance of ferroelectric compounds.…”