Fabrication of textured ferroelectric ceramics by magnetic alignment via gelcasting

Grain-oriented ferroelectric ceramics have attracted more interest recently because they may provide near single crystal properties. In the present study, a novel process combining magnetic alignment and gelcasting was explored to prepare grain-oriented ferroelectric ceramics with different crystal structures. In a strong magnetic field, ceramic particles in slurry were aligned by the magnetic force and then locked in situ by polymerization via a gelcasting technique. This process was found effective for ferroelectric ceramics with a bismuth layer structure (Bi4Ti3O12) and tungsten bronze structure (Sr0.5Ba0.5Nb2O6). The sintered samples show highly anisotropic structure and enhanced physical properties. However for perovskite structured ferroelectric ceramics (BaTiO3), the green compact shows grain orientation, while after sintering the sample become random again.Thus for certain materials using the conventional ceramic processes, i.e., using conventional starting powders, gelcasting under strong magnetic fields (10 T) and pressure-less sintering, the preparation of dense grain-oriented ceramic materials is possible.