Synthesis of zirconia nanopowders from various zirconium salts via polyacrylamide gel method

Pure monoclinic zirconia nanopowders were synthesized via a simple, fast and low cost method; polyacrylamide gel method. Also, the effect of initial salt precursor on thermal behavior of gel network and structure of the synthesized nanoparticles was studied with thermogravimetric and differential thermal analysis (TG-DTA), X-ray diffraction (XRD) and transmission electron microscopy (TEM) analysis. The XRD results showed that the presence of nitrate ions not only retarded the crystallization, but also delayed the tetragonal to monoclinic phase transformation of zirconia nanoparticles which resulted in smaller particle sizes in comparison with the chloride samples. However, TG-DTA analysis confirmed accelerator role of nitrate ions on degradation of polymeric network. Thus, it was expected that zirconia nanopowders synthesized by nitrate samples have bigger sizes than the chloride base powders. Therefore, the presence of nitrate ions affects the synthesized nanoparticle size via two different mechanisms: the retarded crystallization and polymeric network degradation. But, TEM images revealed that the controlling mechanism is the former one.