XANES and EXAFS study of the local order in nanocrystalline yttria-stabilized zirconia

Abstract

The local order around Zr and Y atoms of nanocrystalline yttria-stabilized zirconia (YSZ) powders with different grain sizes has been investigated by x-ray absorption spectroscopies. The samples were prepared by means of mechanical alloying with or without subsequent sintering treatment and also by milling commercial YSZ. Our study is motivated by the interest in the electrical properties of grain boundaries and the controversy about the level of disorder in the intergrain regions in nanocrystalline YSZ. The x-ray absorption near edge structure (XANES) analysis indicates that the local order of all the sintered samples is independent of the grain size. This is confirmed by the analysis of the extended x-ray absorption fine structure, which points out also that, in contrast to that found in sintered samples, the local order around the cation in the samples milled without further sintering treatment extends only to the first coordination shell. Finally, the results of ab initio Zr K-edge XANES calculations lead us to conclude that the observed changes of the shape of the white line are not related to a phase transformation but reflects the short-range order present in the as-milled samples.

Relationships between structural and electrical properties in mixed conductors duplex materials in the ZrO2-Y2O3-TiOColomer1, Díaz‐Moreno2, Boada3 et al. 2014Phys. Rev. BSelf Cite

“…Similarly, the energy position of the D and E structures shifts towards higher energies for the cubic phase. The latter results indicate the decrease of the first neighbors Zr-O interatomic distance upon a tetragonalto-cubic transformation, in agreement with previous results found for YSZ compounds [33][34][35][36][37][38]. The variation of the B/C intensity ratio is also related to the different crystal structure.…”

“…4(b), the Zr K-edge k 3 -weighted EXAFS signals of both tetragonal 2Y12T2h and cubic YZS c-10 samples show differences in the relative intensity of several spectral features, marked with arrows in Fig. 4(b) [33][34][35][36][37]. This comparison clearly shows the coincidence of the EXAFS spectra of both the cubic phase in the 10Ti8h and 15Ti2h duplex samples and of the cubic c-10 sample, which increases the level of confidence in the procedure we have followed.…”

“…Thus, we have taken sample 2Y12T2h as our tetragonal reference. Previously recorded spectra [33] on commercial powders of 10% mol YSZ (Tosoh-Europe) and ZrO 2 (Alfa Aesar, Europe), hereafter labeled c-10 and C-Zr, were also used as references for the cubic and the monoclinic phases, respectively.…”

RF plasma enhanced MOCVD of yttria stabilized zirconia thin films using octanedionate precursors and their characterization

“…As the concentration of yttria in the films increases, the absorption edge becomes broader and then splits into two. When compared with theoretical spectra of different phases of zirconia, it is inferred that XANES spectra for films A, B and C agree with presence of predominant monoclinic, tetragonal and cubic phases respectively as reported by Dura et al [31]. Fig.…”

“…It can also be observed that no Zr Zr correlation is found in these samples except a small peak between 3 and 4Å for film B indicating that the cation-cation network is more ordered in this tetragonal dominated film as compared to the other two films which corroborates the XRD results also as described above. As reported by Dura et al there is amplitude reduction of peak corresponding to Zr Zr correlation in Fourier transform of nanocrystalline materials and hence no Zr Zr correlation is found for films A and C [31].…”