High-resolution and analytical TEM investigation of metastable-tetragonal phase stabilization in undoped nanocrystalline zirconia.
Submicron and nano-sized nanocrystalline pure zirconia (ZrO2) powders having metastable tetragonal and tetragonal-plus-monoclinic crystal structures, respectively, were synthesized using the sol-gel technique. The as-precipitated and the calcinated ZrO2 powders were analyzed for their morphology, nanocrystallite size and structures, aggregation tendency, local electronic properties, and elemental compositions by conventional and high-resolution transmission electron microscopy and field-emission analytical electron microscopy, including energy-dispersive X-ray and electron energy-loss spectroscopies. The results from this study indicate that a combination of nanocrystallite size, strain-induced grain-growth confinement, and the simultaneous presence of the monoclinic phase can lead to stabilization of the metastable tetragonal-phase in undoped ZrO2. As a result, the tetragonal phase is stabilized within ZrO2 nanocrystallites up to 100 nm in size, which is 16 times larger than the previously reported critical size of 6 nm.
Oleshko
Vladimir P
VP
Department of Materials Science and Engineering, University of Virginia, Charlottesville, Virginia 22904-4745, USA.
Howe
James M
JM
Shukla
Satyajit
S
Seal
Sudipta
S
D003460:Crystallization; D008854:Microscopy, Electron; D046529:Microscopy, Electron, Transmission / Q000379:methods*; D036103:Nanotechnology / Q000379:methods*; D044367:Phase Transition; D033362:Powder Diffraction; D013053:Spectrophotometry; D014965:X-Rays; D015034:Zinc Oxide / Q000737:chemistry; D015040:Zirconium / Q000737:chemistry*
D015040:Zirconium; C028541:zirconium oxide; D015034:Zinc Oxide