Effect of cerium on structural and optical properties of ZnO aerogel synthesized in supercritical methanol

Abstract

Pure ZnO and Ce-doped (5 at.%) ZnO aerogels were prepared by dissociation of dihydrate zinc acetate and cerium nitrate in methanol, followed by drying in supercritical conditions of the solvent. The concentration of zinc acetate solution and the atomic ratio Ce/Zn were fixed at 0.2 mol/L and 0.05 mol/L, respectively. XRD results showed a hexagonal wurtzite structure of ZnO aerogel crystallites and a formation of a separate second phase of ceria cubic phase with fluorite structure and 7.4 nm in size. The introduction of cerium in the solution had a negative effect on the aerogel crystalline quality. The crystallites size was found to be 16 nm in pure ZnO and 27 nm in Ce-doped ZnO aerogels. The grains of Ce-doped ZnO aerogel had torus shaped morphology with hollow centers, but those of pure ZnO were flattened semispheres. The calculated values of different structural parameters showed that cerium ions introduced into the ZnO lattice occupied interstitial sites and Zn ions substituted Ce ones in ceria lattice during the formation process. FT-IR and UV-Vis absorption spectra have not revealed any particularities due to the presence of cerium atoms in ZnO, indicating that Ce (5 at.%) doping of ZnO crystallites synthesized in supercritical methanol did not strongly affect the optical gap of the semiconductor. Micro-Raman studies confirmed the formation of cubic fluorite structure ceria in ZnO aerogel and showed that Raman active modes of ZnO are amplified with the presence of ceria.

PREPARATION AND CHARACTERIZATION OF VISIBLE-LIGHT-DRIVEN Ce-DOPED CdS NANOWIRES FOR PHOTODEGRADATION OF RHODAMINE B

“…This leads to an expansion of unit cell and the size effect. Clearly, the positions of main diffraction peaks of Cedoped CdS were shifted to higher angle because the ionic radius of Ce 3+ ion (1.14 Å [17][18][19][20]) is larger than that of Cd 2+ ion (1.03 Å [21,22]). The unit cell parameters are a = 4.1388 Å and c = 6.7125 Å for pure CdS sample and a = 6.7125 Å and c = 6.6666 Å for the 3% Ce-doped CdS sample.…”

Structural and morphological characterizations of pure and Ce-doped ZnO nanorods hydrothermally synthesized with different caustic bases

“…This vibrational mode indicates high crystallinity of wurtzite ZnO. This mode is typical of P6 3 mc symmetry and originates from the oxygen vibration in ZnO [19,32]. The intense peak at 419 cm −1 is assigned to E 1 (TO) modes of ZnO nanorods, which is due to the presence of oxygen vacancies and/or the interstitials zinc or their complexes [33].…”

“…The cell parameters: a = b=1/( √ 3 sin θ) and c = 1/ sin θ of pure and Ce-doped ZnO were calculated from the positions of the (1 0 0) and (0 0 2) peaks, respectively. The volume of the ZnO hexagonal cell V and the Zn-O or Ce-O bond length L were calculated using reported formulas [19]. The degree of crystallinity Xc is given by [27]:…”

“…Doping is considered as an effective way to improve ZnO properties for various applications. Cerium is one of the rare earth metal elements that has a strong effect on structural characteristics of ZnO nanostructures [6,13,[16][17][18][19]. Ce-doped ZnO nanorods have been synthesized by various methods: wet-chemical method [10], hydrothermal route [14,16], CVD [7] and electrochemical process [18].…”

Synthesis, Structural and Optical Characterization of Titanium Dioxide Doped by (Ce, Yb) Dedicated to Photonic Conversion

“…The lattice parameters a, c and V for the undoped and doped titanium dioxide were calculated from the position (110) peak using the formulas in (Eq. (2)) [42]. Table 2 summarize Ytterbium atoms into TiO2 shifted the position of the peak of TiO2 (Fig.…”