Fabrication of a- and c-axis oriented Zn0.98Al0.02O by a high magnetic field via gelcasting

Highly a- and c-axis oriented Zn_0.98Al_0.02O ceramics were prepared by a combination of the high magnetic field and gelcasting techniques, and their thermoelectric properties were examined. The gelcasting made it possible to align the particles preferentially along the a- and c-axis within a short exposure time in the high magnetic field. The particle orientation was not degraded and disturbed by the gelation and subsequent processing. The c-axis oriented specimen along the ab-plane showed a higher electrical conductivity compared with the a-axis and non-oriented specimens as a result of high electron mobility. The differences in the Seebeck coefficients between oriented and non-oriented specimens were a very small. This study indicated that applying the magnetic alignment via gelcasting method provides effective and versatile techniques to fabricate the grain oriented materials without hindering the thermoelectric properties