Conduction mechanisms and relaxation phenomena along with electronic transition of ZnO/ZnNb2O6/Nb2O5 composite

Metal-doped niobate pyrochlores and double-perovskites for glycerol valorization: structural and electronic properties and DFT calculations

“…Besides, the columbite-type orthorhombic structure belongs to the space group Pbcn and possesses lattice constants a = 14.208 Å, b = 5.726 Å, and c = 5.04 Å and lattice angles α = β = γ = 90°, in line with the findings. 33,34 A closer observation in the curve fitting of the XRD patterns by the Rietveld refinement confirms the presence of the aforesaid phases of the CuNb and ZnNb samples (Fig. S 2 , ESI†).…”

“…In addition, the parameters including unit cells, lattice constants and angles are found to be consistent with the parameters reported earlier. 32,34 Interestingly, the XRD peaks match with those of the monoclinic Zn 3 Nb 2 O 8 pyrochlore structure (ICSD 36290, space group C2/c). This may be due to the combined effects of the amounts of the ZnO and Nb 2 O 5 precursors used during the preparation of the sample and the calcination temperature leading to the mixture of Zn 3 Nb 2 O 8 and ZnNb 2 O 6 , in agreement with the findings.…”

“…Three distinct Raman spectra are observed for the pyrochlores. As discussed earlier, [34][35][36][37] the columbite Me 2+ Nb 2 O 6 type niobates can be indexed to the orthorhombic or monoclinic structures (or both), depending on the calcination temperatures. As for the orthorhombic cell unit, the Me 2+ (Zn, Cu or Pb) and Nb cations are arranged at the center of the octahedron, close to six oxygen atoms.…”

Impedance Spectroscopy and Structural Characterization of Nanostructured ZnO and Hf-Doped ZnO Ceramics

“…This case due to the change in the electronic behavior of ZnO at this temperature. 58 In Fig. 12b, there is no peak associated with relaxation time at 300 K and 350 K, but as can be seen in the insets of Fig.…”

“…To fit the models to impedance data, constant phase elements (CPE), which are identified as an imperfect/faulty capacitor are often used. 31,54,[58][59][60] The equivalent circuit for 300 K,…”