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Structural and optical characteristics of cadmium doped Ce0.80(Zr0.20-xCdx)O2 (x = 0 - 0.20) ceria: An experimental and density functional theory (DFT) investigations.

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Title: Structural and optical characteristics of cadmium doped Ce0.80(Zr0.20-xCdx)O2 (x = 0 - 0.20) ceria: An experimental and density functional theory (DFT) investigations.
Authors: Kumar, Brajesh1 (AUTHOR), Jaiswal, Shivendra Kumar1 (AUTHOR) skj@nitp.ac.in, Prasad, Satyajit1 (AUTHOR), Kumar, Rajesh2 (AUTHOR), Srivastava, Pooja3 (AUTHOR)
Source: Ceramics International. May2026:Part B, Vol. 52 Issue 13, p22883-22895. 13p.
Subjects: Cadmium, Cerium oxides, Optical properties, Crystal structure, Band gaps, Doping agents (Chemistry), Density functional theory, Oxygen vacancy
Abstract: Ceria-based oxides find relevance for wide-range applications e.g. fuel cell technologies, hydrogen production, energy storage and conversion, biosciences, and advanced sensing devices. In the present study, zirconium and cadmium co-doped Ce 0.80 (Zr 0.20-x Cd x)O 2 (x = 0 - 0.20) oxides were synthesized via sol-gel route and systematically characterized for their structural and optical properties, supported by density functional theory (DFT). X-ray diffraction-cum-Rietveld refinement data confirm fluorite-type cubic structure with space group Fm 3 ‾ m and Z = 4. The lattice parameters (a f) lie in the range of ∼5.398 - 5.412 Å for x = 0 - 0.20, and an anomalous behaviour, i.e., expansion-contraction-expansion, is observed with increasing cadmium content (x) with average size in the range of ∼90-150 nm. A clear correlation has been found between the calculated bond length with lattice parameter in Ce 0.8 (Zr 0.20-x Cd x)O 2 oxides. Density functional theory (DFT) calculations independently validate these structural trends with cadmium (x) substitution. Specifically, the Ce-O bond length was 2.369 Å and upon cadmium substitution at zirconium sites completely, the bond length increases from ∼2.299 Å to ∼2.338 Å. The optical absorption peak at ∼266 nm corresponds to the charge transfer transition between the valence band 2p (O2−) and conduction band 4f (Ce4+) orbitals. An additional peak reveals trapped states between valence and conduction bands. The theoretically calculated band gaps are ∼1.561, 1.417 and 1.202 eV for pure CeO 2 , Ce 0.80 Zr 0.20 O 2 and Ce 0.8 Cd 0.20 O 2 samples, respectively. Raman mode at ∼462 cm−1 attributed to a triple degenerated F 2g vibrational symmetry/mode of fluorite-type CeO 2 structure. Bands at ∼1119 and 1361 cm−1 further confirm oxygen vacancy and defect-states. These results demonstrate that Zr/Cd co-doping in ceria offers an effective strategy for defect and band gap engineering, making these materials promising for ionic conduction and energy-related applications. [ABSTRACT FROM AUTHOR]
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Database: Engineering Source
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Abstract:Ceria-based oxides find relevance for wide-range applications e.g. fuel cell technologies, hydrogen production, energy storage and conversion, biosciences, and advanced sensing devices. In the present study, zirconium and cadmium co-doped Ce 0.80 (Zr 0.20-x Cd x)O 2 (x = 0 - 0.20) oxides were synthesized via sol-gel route and systematically characterized for their structural and optical properties, supported by density functional theory (DFT). X-ray diffraction-cum-Rietveld refinement data confirm fluorite-type cubic structure with space group Fm 3 ‾ m and Z = 4. The lattice parameters (a f) lie in the range of ∼5.398 - 5.412 Å for x = 0 - 0.20, and an anomalous behaviour, i.e., expansion-contraction-expansion, is observed with increasing cadmium content (x) with average size in the range of ∼90-150 nm. A clear correlation has been found between the calculated bond length with lattice parameter in Ce 0.8 (Zr 0.20-x Cd x)O 2 oxides. Density functional theory (DFT) calculations independently validate these structural trends with cadmium (x) substitution. Specifically, the Ce-O bond length was 2.369 Å and upon cadmium substitution at zirconium sites completely, the bond length increases from ∼2.299 Å to ∼2.338 Å. The optical absorption peak at ∼266 nm corresponds to the charge transfer transition between the valence band 2p (O2−) and conduction band 4f (Ce4+) orbitals. An additional peak reveals trapped states between valence and conduction bands. The theoretically calculated band gaps are ∼1.561, 1.417 and 1.202 eV for pure CeO 2 , Ce 0.80 Zr 0.20 O 2 and Ce 0.8 Cd 0.20 O 2 samples, respectively. Raman mode at ∼462 cm−1 attributed to a triple degenerated F 2g vibrational symmetry/mode of fluorite-type CeO 2 structure. Bands at ∼1119 and 1361 cm−1 further confirm oxygen vacancy and defect-states. These results demonstrate that Zr/Cd co-doping in ceria offers an effective strategy for defect and band gap engineering, making these materials promising for ionic conduction and energy-related applications. [ABSTRACT FROM AUTHOR]
ISSN:02728842
DOI:10.1016/j.ceramint.2026.03.345