Interfacial effect: magnetism in pure ZrO₂, ZnO and SiO₂ coated core/shell/shell hybrid nanoparticles

We report the room temperature magnetic behavior of pure and dual shells ZnO as well as SiO₂ coated ZrO₂ core–shell nanoparticles. All the samples, viz., ZrO₂, ZrO₂/ZnO and ZrO₂/ZnO/SiO₂ nanocrystallites have been successfully synthesized by chemical precipitation method. The XRD studies confirm the tetragonal structure for pure Zirconia and hexagonal wurtzite structure for ZnO coated ZrO₂ samples. Average size of nanocrystallites has been observed to increase due to the incorporation of the shells over ZrO₂. Studies of SEM, TEM and EDAX were used to determine the morphology, size and presence of elements in the ZrO₂ nanocrystallites. The existence of SiO₂ on ZrO₂@ZnO was characterized by FT-IR measurement. The VSM studies have shown that the dual shells ZnO as well as SiO₂ coated ZrO₂ samples exhibit S-shaped paramagnetic behavior of the samples with little variations. The paramagnetic ordering of this core–shell nanostructure was mainly attributed to oxygen vacancies and also to the minor impurity phases in Zirconia and ZnO lattices.