Structural Changes of Scandia‐Doped Zirconia Solid Solutions: Rietveld Analysis and Raman Scattering

Abstract

Powder X-ray diffractometry (XRD) and Raman scattering measurements were used to study the structural changes of compositionally homogeneous metastable ZrO 2 solid solutions induced by ScO 1.5 doping. The crystal structures of monoclinic, tetragonal, cubic, and rhombohedral (Sc 2 Zr 7 O 17 , ␤-phase) solid-solution phases have been refined by using the Rietveld analysis of the XRD data at room temperature of arc-melted ZrO 2 -XScO 1.5 (X = 0, 2, . . . , 20, and 22 mol%) samples. The results can be interpreted as indicating that the structures of the monoclinic and tetragonal phases approach those of the tetragonal and cubic phases, respectively, by ScO 1.5 doping. Raman scattering, as well as XRD, was useful to investigate the phase assemblage. Moreover, we could obtain Raman spectra of the ␤-phase probably for the first time.

Retention at room temperature of the tetragonal t″-form in Sc2O3-doped ZrO2 nanopowders

“…The monoclinic and rhombohedral phases exhibit poor electrical properties, while the tetragonal and cubic ones are useful for applications. The existence of rhombohedral phases, such as ␤, ␥ and ␦, is an important feature of ZrO 2 -Sc 2 O 3 materials [1,2] and they have not been observed in other ZrO 2 -based systems.…”

Performance of solid oxide electrolysis cells based on scandia stabilised zirconia

“…12 In Figure 1(left) we present a SEM micrograph showing the typical microstructure of the sample. The estimated relative density determined by the Archimedes method is 98.6%, and the average grain size, using the linear intercept method, is approximately 5 µm.…”

Investigation of NdxY0.25–xZr0.75O1.88 inert matrix fuel materials made by a co-precipitation synthetic route

“…The materials made by the co-precipitation method are more kinetically labile due to the intimate mixing of the component cations on an atomic level. [51][52][53]63 The XAS results showed that the local coordination environments around the Zr and Y cations were largely similar in the materials made by the co-precipitation method and the ceramic method. The Y K-edge EXAFS and XANES spectra from the compounds made by co-precipitation and those made by ceramic synthesis were identical when the co-precipitated materials were annealed at 1500°C, with the exception of Nd 0.20 Y 0.05 Zr 0.75 O 1.88 .…”

“…This stability is likely driven by the kinetics of the cubic to tetragonal ZrO 2 and cubic to monoclinic ZrO 2 phase transitions, which are controlled by the diffusion of cations within the matrix. [51][52][53][54] In the case of the coprecipitation synthesis, the cations are already intimately mixed at an atomic level, facilitating a faster reaction. This is evident by the difference in the annealing times required to induce phase changes, which were much shorter in the case of the co-precipitation route (24 h) as compared to the materials made by the ceramic route (5 days).…”