91Zr NMR characterisation of phases in transformation toughened zirconia.
A detailed 91Zr NMR investigation is presented of the five component (cubic, monoclinic, tetragonal, orthorhombic and delta) phase mixture in the transformation toughened engineering ceramic, magnesia-partially-stabilised zirconia (MgPSZ). The phases are distinguished on the basis of the quadrupole interaction displayed in the powder pattern of the 91Zr(1/2, -1/2) transition. This paper reports: (i) the first characterisation of the magnesia-fully-stabilised cubic phase at the eutectic composition (13.5 mol% MgO); (ii) the observation of a poorly ordered tetragonal phase on fast cooling ZrO2 (9.3 mol% MgO) from the cubic phase field at 1720 degrees C, and the subsequent growth and ordering of the tetragonal phase precipitates due to further annealing; (iii) the observation of the (partial) transformation of the cubic phase to the ordered delta-phase (Mg2Zr5O12) on annealing MgPSZ at 1100 degrees C for 8 h; and (iv) the observation of the transformation of the tetragonal phase into the orthorhombic phase after cooling in liquid nitrogen, and the reverse transformation after heating to 600 degrees C.
Bastow
T J
TJ
CSIRO Division of Materials Science and Technology, Clayton, Victoria, Australia.
Smith
M E
ME
D003460:Crystallization; D007554:Isotopes; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D015394:Molecular Structure; D009502:Neutrons; D015040:Zirconium / Q000737:chemistry*
D007554:Isotopes; D015040:Zirconium; C028541:zirconium oxide