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Suitability of Raman Spectroscopy for Assessing Anisotropic Strain in Thin Films of Doped Ceria
摘要： A protocol for characterizing relaxation of anisotropic strain in thin films of 10 mol% Eu- or Sm-doped ceria is described. The method is based on comparison of Raman spectra and X-ray diffraction patterns from substrate-supported films, displaying in-plane compressive strain (initial state), with analogous data from 2 mm diameter self-supported films (i.e., membranes), prepared by partial substrate removal (final state). These membranes are found to be relaxed, i.e., approximately unstrained, but with increased unit cell volume. The effective (i.e., 2-state) Grüneisen parameter of the F2g Raman active mode for these films is calculated to be 0.4 ± 0.1, which is ≈30% of the literature value for the corresponding ceramics under isostatic pressure. On this basis, it is found that the observed red-shift of the F2g mode frequency following isothermal strain relaxation of the doped ceria thin films cannot be determined solely by the increase in average unit cell volume. The study presented here may shed light on the suitability of Raman spectroscopy as a technique for characterizing strain in lanthanide-doped ceria thin films.
关键词： doped ceria,Raman spectroscopy,Grüneisen parameter,anelastic relaxation
更新于2025-09-23 15:23:52
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Flash Sintering Samaria-Doped Ceria–Carbon Nanotube Composites
摘要： Composite ceramic green pellets were prepared by attrition milling a mixture of (CeO2)0.8(Sm2O3)0.2 (samaria-doped ceria, SDC) ceramic powder and carbon nanotubes (CNTs), followed by uniaxial and isostatic pressing. The pellets were sintered inside a dilatometer by applying AC electric fields at 850 °C and limiting the electric current to 1 A, achieving 20.2% final shrinkage. The SDC samples reached 13.3% shrinkage under the same conditions. Higher average grain sizes were measured in specimens flash sintered with CNTs. Impedance spectroscopy analyses show that the specimens flash sintered with addition of CNTs have higher electrical conductivity. Higher delivered Joule heating at the interfaces due to the presence of the electronic conductors (CNTs) are proposed as the main reason for that improvement of the electrical behavior.
关键词： flash sintering,solid electrolytes,carbon nanotubes,impedance spectroscopy,samaria-doped ceria
更新于2025-09-19 17:15:36
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Investigation of Interface Diffusion in Sputter Deposited Gd0.1Ce0.9O1.95 Thin Buffer Layers on Y-Stabilized Zirconia Crystalline Substrates for Solid Oxide Cells Applications
摘要： This paper presents the results concerning the investigation of the morphological and structural properties of Gd0.1Ce0.9O1.95 layers deposited on crystalline (111) YSZ subtrates by RF magnetron sputtering. Room temperature as-grown samples have been annealed at different temperatures from 600°C to 1300°C. Atomic Force Microscopy analysis shows an increase in the average grain size dimensions with increasing annealing temperatures. X-Ray Diffraction measurements indicates a preferential growth of the grains along the (111) direction with a decrease in the evaluated c-axis as a function of the annealing temperature, probably related to an over-oxidation of the samples. X-Ray Reflectivity studies, performed on thin layers annealed at temperatures from 700-1000°C, points out the presence of zones with different densities and roughness at the layer/substrate interface and at the layer/vacuum surface. The behaviour of these zones as a function of temperature has been investigated. The obtained results seem to exclude the presence of consistent inter-diffusion phenomena at the GDC/YSZ interface.
关键词： Solid oxide cells,X-ray reflectivity,Reciprocal space map,RF magnetron sputtering,Yttrium stabilized Zirconia,Gadolinium doped Ceria,Interdiffusion
更新于2025-09-04 15:30:14