Preparation and characterization of unique zirconia crystals within pores via a sol–gel-hydrothermal method

Unique ZrO2 crystals within pores were prepared by a sol–gel-hydrothermal method and characterized by XRD, TG/DTA, TEM, SEM, and N2 adsorption–desorption isotherms. Results show that the dried sol–gel was converted into monoclinic zirconia crystals after calcined above 550 °C. The crystal sizes of the zirconia single crystal were in the range of 20–70 nm. A number of irregular pores were embedded within the zirconia crystals. This unique structure was obtained due to the combination of sol–gel and hydrothermal treatments.