Phase stability and microstructure evolution of MgO‐ZrO ₂ and MgO‐6YSZ ceramic fibers

Abstract In this work, MgO‐ZrO ₂ and MgO‐6YSZ ceramic fibers were prepared with sol‐gel method via electrospinning. Polymorph stability and microstructure evolution of zirconia fibers were fully characterized by X‐ray diffraction, Raman spectra, X‐ray photoelectron spectroscopy, and Scanning electron microscope. The results indicated that tetragonal zirconia for MgO‐ZrO ₂ was obtained and cubic zirconia could be fully stabilized for MgO‐6YSZ with MgO molar fractions varying from 0.1 to 0.5 at 800°C. Monoclinic phase appeared with MgO molar fractions even up to 0.5 for MgO‐ZrO ₂ system and partially or fully stabilized zirconia could be achieved for MgO‐6YSZ at 1000°C and 1200°C. Grain size was gradually decreased with increasing of MgO content at 800°C both for MgO‐ZrO ₂ and MgO‐6YSZ ceramic fibers. The grain size of both systems increased with MgO molar fractions varying from 0.1 to 0.2 and then decreased at higher contents at 1000°C and 1200°C. A discussion on relationship among MgO state and the phase stability and grain size was presented. This work shows surface excess and solid solution of MgO predominantly controlled the phase stability and microstructure evolution of zirconia fibers.