effect of crystalline size on the structure of copper doped zirconia nanopaticles synthesized via sol-gel

the stabilized zirconia with different cu contents synthesized via sol-gel method. the samples were prepared by hydrolysis and condensation of orgnomatelic sol. after that the result gels were dried at 80 °c and then calcined at various temperatures.  ِ the differential thermal analysis (dta), x-ray diffraction (xrd), field emission scanning electronic microscopy (fesem) and transmission electronic microscopy (tem) were used to determine the characteristics of nanoparticles. unlike the stable pure zro2 that has monoclinic structure at room temperature, the synthesized pure zro2 and zro2-cuo powders have been cubic and tetragonal structure at room temperature after calcinations. moreover, it is obtained those changes in the crystallite size affect the stabilization of tetragonal or cubic structure at room temperature, and increase in content of dopant favored decrease of the crystallite size and metastabilization of both tetragonal and cubic polymorphs.