Stabilization of tetragonal phase of nanostructured Fe_x/ZrO₂ system (0 ≤ x ≤ 25) prepared by modified sol-gel method

Abstract

In the present study, Fex/ZrO2 (0 ≤ x ≤ 25) nanoparticles were synthesized by a facile modified Sol-Gel method. Stabilization of the tetragonal phase of ZrO2 is studied as a function of both the Fe incorporation ratios and thermal treatment. The Fe incorporation ratios are tested up to the extreme just before FeO and Fe2O3 phases are formed separately. The prepared Fex/ZrO2 nanoparticles XRD analysis depicts the formation of zirconium oxide at different Fe ratios in the nanoscale with an excellent degree of crystallinity in the tetragonal phase. The effect of thermal treatment on stabilizing the tetragonal phase of Fex/ZrO2 nanoparticles is extensively studied. The phase transition to the monoclinic phase is determined as function of Fe incorporation ratios and annealing temperatures. The optical absorbance spectra showed that the optical band gap decreased with increasing Fe ratios without the formation of doping bands which confirms the formation of Fex/ZrO2 single matrix.

Barium incorporated zirconium dioxide nanostructures synthesized by sol-gel route and investigation of their structural, thermal and spectroscopic characteristic in the stabilized tetragonal phase

“…The aim of this work is to determine the appropriate ratio for zirconia to suit different purposes. In contrast to the previous study [7], which used varied Fe doping ratios in zirconia lattices at various annealing temperatures until arrive at 800 °C which considered the best temperature for the greatest ratio, Ba is used to stabilize the tetragonal phase at higher temperatures, which represent the ideal case. The lattice parameters for pure zirconia and zirconia doped with different Ba ratios were calculated and tabulated in Table 1.…”

“…Tauc's law [20], which describes the relationship between incident photon energy and the absorption coefficient in the high absorption region of semiconductor materials, was used to calculate the optical band gap of the fabricated samples. (7) Where B is a probability constant, h is Planck's constant, and ν is the optical frequency, so that hν is the energy of the incident photon, E g is the optical band gap energy, and n is an exponent whose value depends strongly on the type of the electronic transition. Therefore, n takes 1/2 for the direct transition and 2 for the indirect transition.…”

“…Therefore, using zirconia material for most applications requires stabilizing cubic and tetragonal phases over a wider and higher temperature range. In order to produce a new material that is superior to either one alone, scientists are therefore trying to stabilize the tetragonal phase by changing the variables of the production method or by doping with other metal oxides [7].…”