Influence of the crystal structure on the physical properties of monoclinic ZrO2 nanocrystals

The influence of the crystal structure on the physical properties of monoclinic ZrO2 nanocrystals is investigated by an annealing treatment. Monoclinic ZrO2 nanocrystals with diameters of approximately 20 nm are synthesized by a hydrothermal method using subcritical water. The nanocrystals have chemisorbed water molecules, hydroxides and nitro groups on their surfaces. The crystallographic structures are reformed by annealing the nanocrystals at 800 °C for 5 h. This treatment causes the crystallite sizes to increase, the crystal lattice to shrink and some of the molecules chemisorbed on the surfaces to be lost. The annealing treatment leads to there being fewer lattice defects, and to the modification of surface characteristics of the nanocrystals. The treatment also changes the optical absorption characteristics of the nanocrystals. The magnetic moments caused by lattice defects are identified.

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