Crystal Orientation of Layered Functional Materials by Colloidal

Processes under Magnetic Field

Abstract

  Magnetic alignment using static magnetic field (SF) and modulated rotating magnetic field (MRF) enables formation of uni-axial and tri-axial grain arrangement at room temperature for substances with magnetic anisotropy, respectively. In this review article, we introduce two topics to show high potential of combination of magnetic alignment and colloid processes. The former topic is uni-axial orientation of a layered thermoelectric (TE) cobaltite by electrophoretic deposition in SFs. Using this technique, the fabrication of multilayered TE module containing c-axis-oriented cobaltite layer is demonstrated. The latter topic is the fabrication of tri-axially grain-aligned ErBa₂Cu₄O₈ (Er124) green pellets by slip-casting under MRFs. The degrees of tri-axial orientation are sensitive to viscosities of suspensions. So far, an Er124 green pellet with the degree of inplane orientation with ～7° has been successfully fabricated by control of viscosity of suspensions and introduction of oscillation type of MRF.