Crystal Growth and Dielectric Properties of New Ferroelectric Barium Titanate: BaTi2O5

Abstract

Single crystals of the ferroelectric BaTi 2 O 5 and BaTiO 3 were prepared from a solution of 33-mol% BaO and 67-mol% TiO 2 by a rapid cooling method. The dielectric constant (ε ) and dielectric loss tangent (tanδ) were measured in a wide temperature range of 10-860 K and in a frequency range of 0.1-3,000 kHz. The ε along the b-axis of the BaTi 2 O 5 crystal, prepared in air, shows a sharp dielectric anomaly reaching 30,000 at the ferroelectric Curie temperature of T C = 752 K. By contrast, the crystal prepared in a reducing atmosphere shows a diffuse phase transition near T C = 703 K. The values of ε and tanδ are compared between these three crystals consisting of two kinds of BaTi 2 O 5 and one BaTiO 3 .

Preparation and property of BaTi2O5 ceramics by arc-melting and spark plasma sintering

“…On the other hand, as indicated in the literatures [15][16][17]20], T C of BaTi 2 O 5 varies with the fabrication conditions. For example, BaTi 2 O 5 crystals prepared in air shows a higher Curie temperature of 752 K; By contrast, the crystals prepared in a reducing atmosphere show a diffuse phase transition near T C 0703 K due to the oxygen vacancies [15].…”

“…For example, BaTi 2 O 5 crystals prepared in air shows a higher Curie temperature of 752 K; By contrast, the crystals prepared in a reducing atmosphere show a diffuse phase transition near T C 0703 K due to the oxygen vacancies [15]. The existence of those mobile oxygen vacancies appears to induce a decreased T C and broaden the phase transition, as observed in PLZT [27].…”

“…Unfortunately, BaTi 2 O 5 was reported to be easily decomposed into BaTiO 3 and Ba 6 Ti 17 O 40 [8][9][10], and difficult to synthesize by the conventional solid-state reaction. Although the processes of sol-gel [11,12], hydrothermal reaction [13], containerless processing [14], rapid cooling [15,16], floating zone [17,18], arc-melting [19] have been developed to prepare singlephased BaTi 2 O 5 in forms of micro-powders, nano-belts, glass spheres, needle-like or rod-like crystals, both the densification and dimension of those products are not satisfied. For the purpose of practical and wider applications, dense and large-scaled BaTi 2 O 5 ceramics should be produced, especially as the target materials for further preparing BaTi 2 O 5 films by physical vapour deposition.…”

Synthesis of BaTi2O5 powders by stearic acid gel method

“…Moreover, the development of lead-free ferroelectric materials such as BaTi 2 O 5 is a promising way to protect the natural environment. Therefore, much attention has been focused on the synthesis of BaTi 2 O 5 recently [3][4][5][6][7][8].…”

Nanocomposite ceramics based on La-doped BaTi2O5 and BaTiO3 with high temperature-independent permittivity and low dielectric loss

“…On heating solgel-derived samples at higher temperatures, ≥1,150°C, BT 2 decomposes to give a mixture of BaTiO 3 (BT) and Ba 6 Ti 17 O 40 (B 6 T 17 ). There was some evidence that the value of T c in sol-gel derived ceramics varied somewhat over the range 450-470°C, depending on sample heat treatment in air [5]; in addition, single crystals grown in reducing atmosphere had lower T c , ∼400°C, than those grown in air, ∼460°C [14,15] Possibly, therefore, BT 2 is capable of a significant, but limited variation in its stoichiometry, either Ba:Ti ratio and/or oxygen content.…”