Ionic and electronic conductivity of Yb2+xTi2−xO7−x/2 materials

New oxide-ion conductor Ho2(Ti1.904Ho0.096)O6.952: structure and conductivity

“…5. One may ascribe the plateau region to predominant ionic conductivity and significant n-type conductivity is expected to be responsible for the increase in total conductivity under very reducing conditions, as observed for Yb 2 (Ti 1.904 Yb 0.096 )O 6.952 samples [17].…”

Ordering processes in Ln2TiO5 (Ln=Dy–Lu): The role of thermal history

“…Its conductivity was found to be an order of magnitude lower than that of the fluoritelike Yb 2 TiO 5 and almost three orders of magnitude lower than that of the disordered pyrochlore Yb 2 Ti 2 O 7 obtained via furnace cooling from 1600 • C (Fig. 6) [2,7,18].…”

“…Ln 2+x M 2−x O 7−ı (Ln = Sm-Lu; M = Ti, Zr, Hf; x = 0-0.67) pyrochlores have attracted considerable attention because some of them are comparable in high-temperature oxygen ion conductivity to the well-known solid electrolytes ZrO 2 -8 to 12 mol% Y 2 O 3 [1][2][3][4][5]. Of particular interest are the Ln 2+x Ti 2−x O 7−ı (Ln = Er-Lu, x = 0-0.096) and Ho 2+x Ti 2−x O 7−ı (x = 0.48-0.67) pyrochlore-like titanates, which offer the highest oxygen ion conductivity in this family of materials, up to ∼1.4 × 10 −2 S/cm at 800 • C [1,2,6,7].…”

“…Of particular interest are the Ln 2+x Ti 2−x O 7−ı (Ln = Er-Lu, x = 0-0.096) and Ho 2+x Ti 2−x O 7−ı (x = 0.48-0.67) pyrochlore-like titanates, which offer the highest oxygen ion conductivity in this family of materials, up to ∼1.4 × 10 −2 S/cm at 800 • C [1,2,6,7]. The conductivity of the Ln 2 O 3 -rich (x = 0.63-0.74) Ln 2+x Ti 2−x O 7−ı titanates of the small lanthanides Ln = Er-Lu, which have the fluorite structure according to X-ray diffraction (XRD) data, is one to two orders of magnitude lower than that of the pyrochlore-like Ln 2+x Ti 2−x O 7−ı (Ln = Er-Lu, x = 0-0.096).…”

Interpretation of impedance spectra based on local minima of imaginary Z vs frequency

“…3). These materials allow significant off-stoichiometry with changes in transport properties [20]. The impedance spectra shown in Figs 6.…”