Synthesis, characterization of undoped and copper-doped hafnium oxide nanoparticles by sol-gel method

In this paper, we report that hafnium oxide nanoparticles with different copper contents (0.00, 0.02, 0.04, and 0.06%) are successfully synthesized by sol-gel technique. The influence of the copper concentration and observed the morphological and structural changes of the obtained nanoparticles. For characterization, XRD observed that the crystalline structure depends on the doping content. The synthesis samples are undoped hafnium and copper-doped hafnium oxide nanoparticles, which crystallographic change from cubic to monoclinic phase with increasing doping concentration. The presence of Hf, Cu, and O in the synthesis sample was confirmed by EDS analysis. Energy gaps of the synthesized samples were estimated from the ultraviolet-visible absorption spectrum as well as Tauc's plot which infers that the energy gap decreases with the increase of Cu content. Fourier transform infrared spectrum confirms the cadmium dopant through peak shifting from 538 to 650 cm(-1). PL showed an emission peak at 360 nm that strongly confirmed the UV region and intensity of emission peak increase with increase dopant. SEM and TEM study reveal that the synthesized samples consist of spherical morphology and the particle size varies between 34 and 43 nm. The electrical resistivity decreases from 28 to 16 omega with doping content increasing which indicates that the conductivity of the nanomaterial is improved.