Grain Orientation and Electrical Properties of Hot-Forged Bi₄Ti₃O₁₂Ceramics

Abstract

The effect of grain orientation on the dielectric properties of hot-forged ferroelectric Bi4Ti3O12 ceramics has been investigated and the properties are compared with ordinarily fired ones. The degree of grain orientation f calculated from X-ray diffraction patterns is found to be as large as 0.95. The temperature dependences of the dielectric constant εs and loss tangent tan δ are measured with a Q-meter at 12 MHz in the perpendicular [⊥] and parallel [//] directions to the forging axis, and considerable anisotropies, such as εs[⊥]/εs[//]=5 at the Curie temperature of about 680°C, are seen. The remanent polarization Pr is calculated for both cases of perfect (f=1) and random (f=0) grain orientations. Observed Pr values from hysteresis loops are smaller than calculated ones, the ratio of the former to the latter being about 82% for the hot-forged ceramics.

Textured Development of Feeble Magnetic Ceramics by Colloidal Processing Under High Magnetic Field

“…1) Textured ceramics have been produced by a variety of techniques; such as tape casting, 2) hot forging or pressing, 3), 4) and templated or seeded grain growth. 5)7) Ceramic platelets, fibers or whiskers are used as seeded particles along with some additives to promote the anisotropic grain growth during sintering.…”

Theoretical Analysis on Crystal Alignment of Feeble Magnetic Materials under High Magnetic Field

“…Ceramics having textured structures can be produced by such processes as templated or seed grain growth, 1,2) hot forging or pressing 3,4) and tape casting. 5) On the other hand, since technologies of superconducting magnets were developed, high magnetic field has become one of the effective ways to get the textured structures by controlling crystal alignment.…”

Piezoelectric Properties of SrBi4Ti4O15 Ferroelectric Ceramics

“…The number of perovskite layers is represented by m. Due to the layer structure, the compositions exhibit a very high anisotropy of properties. 5 With the known exception of monoclinic BIT, in most Aurivillius phases the structure can be described as orthorhombic below the paraelectricferroelectric phase transition temperature, and polarization takes place in the ab plane. 6,7 The piezoelectric effect is also highest in this plane.…”