Fibrillar Mn3O4–YMnSz well-ordered eutectics with potential functional applications

Directionally solidified eutectics in the 8 mol% Yttria stabilised zirconia and manganese oxide system were fabricated by the laser assisted melt float zone (LFZ) method at different growth rates. The eutectic composition was determined to 0.82 mol% of MnOx. The crystal structure and composition of the eutectic phases were determined by XRD, EBSD, XRF and Raman spectroscopy. An eutectic consisting of cubic Zr0.66Y0.16Mn0.18Ox (YMnSZ) fibres embedded in the twinned tetragonal Hausmannite Mn3O4 matrix was obtained in air. The fibre diameter decreased as the growth rate increased, with values between 80 and 200 nm. YMnSZ fibres grew along the [1 1 1] cubic axis and tetragonal Mn3O4 along [1 1 2], equivalent to the [1 1 0] cubic axis. The eutectic is a mixed conductor with values of 0.2 S/cm at 1100 K. The structure withstands oxide-reduction, yielding new well ordered structures of MnO/YMnSZ and Mn2O3/YMnSZ composites. Potential functional applications of these composites in the fields of magnetism, electroceramics and photonics are suggested.