Fe₃O₄ stabilized zirconia: structural, mechanical and optical properties

Zirconia (ZrO₂) is one of the most well studied transition-metal oxides in the optical and biological fields. The applications area of ZrO₂ can be increased by addition of metal oxides. Aim of this study is to determine the effect of acidic and basic Fe₃O₄ nanoparticles’ (NPs) doping in sol–gel synthesized ZrO₂. Different samples are prepared by varying Fe₃O₄ concentrations, acidic and basic, in the range of 2–10 wt%. Sols of Fe₃O₄ doped ZrO₂ (FOZ) are spin coated onto glass substrates at 3000 rpm for 30 s. FOZ films are annealed at 300 °C for 1 h. It is worth mentioning that Fe₃O₄ nanoparticles (acidic and basic) are used for the first time, to the best of our knowledge, to stabilize zirconia using sol–gel technique. Moreover, completely homogenous FOZ sol is obtained using water as a solvent. X-ray diffraction results confirm the formation of phase pure tetragonal ZrO₂ (t-ZrO₂) along with less intense peak of Fe₃O₄ at 8–10 wt% of basic dopant. Optical spectra reveal that energy band gap lies in the range of 4.8 to 5.0 eV whereas, high value of transmission up to 80 % has been observed in case of basic dopant. Refractive indices vary with the variation in crystal structure and density of the films. Redshift is observed in Fe₃O₄ doped zirconia. Hardness of the samples is in the range of 310 to 962 HV.