On the facile polyvinyl alcohol assisted sol-gel synthesis of tetragonal zirconia nanopowder with mesoporous structure

Abstract A facile template assisted sol-gel method has been used to prepare nanoparticles of tetragonal zirconia (t-ZrO 2 ) with spherical morphology and porous structure along with mono dispersibility. The medium assisting growth of nanoparticles mainly consisted of ZrOCl 2 ·8H 2 O and NH 4 OH as reactants in a 1:2 mixture of Isopropyl alcohol (IPA)-polyvinyl alcohol (PVA) as the dispersing agent. The effect of medium, IPA-PVA mixture on crystallite size and agglomeration was studied and discussed on the basis of XRD and also based on possible surface reactions. More over reacting medium and calcination temperature has vital role in determining the crystallinity and morphology of ZrO 2 . Trials based on mode of addition of the reacting medium followed by calcination provides mesoporous, spheroid, monoclinic zirconia (m-ZrO 2 ) with an average particle size of 15 nm. The sample prepared under optimized conditions (2 wt% PVA-IPA) showed pure tetragonal crystallite phase with an average particle size of 5 nm, surface area of 56 m 2  g −1 , and a mesoporous structure after calcination at 600 °C for 5 h. The tetragonal (t-ZrO 2 ) phase formed were stable and showed spherical morphology up to 600 °C after which the nanostructure was disturbed drastically; the agglomeration leads to structure collapse forming hard conglomerates and finally leads to monoclinic crystalline phase.