Sol–gel zirconia nanopowders with α-cyclodextrin as organic additive

Nanomaterials present unique structural and physicochemical properties due to their ultra fine size of particles that make them very useful in many domains. The most spectacular applications of nanosized zirconia include ceramics, piezoelectrics, refractories, pigments, solid electrolytes, oxygen sensors, catalysts, ultrafiltration membranes, and chromatography packing materials. Nanostructured zirconia powders can be prepared using various methods, such as sol–gel process, coprecipitation, hydrothermal synthesis, and reverse micelle method. The aim of the present work was to prepare zirconia nanopowders through the sol–gel method, using α-cyclodextrin as organic additive and to establish its influence on the structural and textural properties of the obtained product. A white, amorphous ZrO2 powder containing α-cyclodextrin was prepared, which became a crystalline, stable one, after removing the organic matter by thermal treatment. The resulted nanocrystalline powder contains both monoclinic and tetragonal zirconia phases and is very stable. It presents a relatively reduced tendency of agglomeration of particles and contains closed pores which are embedded in the zirconia matrix. The zirconia powders were characterized using the following methods: thermal analysis, IR spectroscopy, UV–vis spectroscopy, X-ray diffraction, and electron microscopy (SEM, TEM, and HRTEM coupled with SAED).

► The sol–gel synthesis of a zirconia powder has been performed, in the presence of α-cyclodextrin as organic additive.
► A crystalline powder consisting from a mixture of monoclinic and tetragonal zirconia phases has resulted after the thermal treatment.
► The organic additive acted the role of metal oxides used as doppants for zirconia powders, avoiding phase transformations.
► The α-cyclodextrin made particles to assume spherical shape and reach fairly uniform size and prevented their agglomeration.
► The organic additive led to a certain porous morphology of the zirconia particles that is pores embedded within grains.