The structural and conductivity evolution of fluorite-type Bi2O3–Er2O3–PbO solid electrolytes during long-term annealing

Structure–property relationships in fluorite-type Bi2O3–Yb2O3–PbO solid-electrolyte materials

“…The conductivity decay results for (BiO 1.5 ) 0.80 (YbO 1.5 ) 0.14 (PbO) 0.06 and (BiO 1.5 ) 0.80 (YbO 1.5 ) 0.11 (PbO) 0.09 are also shown in Figure 3(a), and a comparison between the results obtained here for (BiO 1.5 ) 0.80 (YbO 1.5 ) 0.11 (PbO) 0.09 and in the previous work of Webster et al (2008) for (BiO 1.5 ) 0.80 (ErO 1.5 ) 0.11 (PbO) 0.09 (which also underwent the fcc fluorite-type to β -Bi 2 O 3 -type tetragonal transformation during annealing) are shown in Figure 3(b). Not surprisingly, the conductivity of both (BiO 1.5 ) 0.80 (YbO 1.5 ) 0.11 (PbO) 0.09 and (BiO 1.5 ) 0.80 (ErO 1.5 ) 0.11 (PbO) 0.09 had decayed to a similar σ / σ 0 value (~0.06) after 30 h. The σ / σ 0 value for (BiO 1.5 ) 0.80 (YbO 1.5 ) 0.14 (PbO) 0.06 after 30 h was lower (0.05), which is attributed to the multiphase nature of this annealed material.…”

“…The exceptions were (BiO 1.5 ) 0.70 (YbO 1.5 ) 0.10 (PbO) 0.20 and (BiO 1.5 ) 0.80 (YbO 1.5 ) 0.05 (PbO) 0.15 , which were quenched from 675 °C, and also (BiO 1.5 ) 0.70 (YbO 1.5 ) 0.05 (PbO) 0.25 and (BiO 1.5 ) 0.80 (YbO 1.5 ) 0.02 (PbO) 0.18 , which were quenched from 650 °C to avoid melting. Each quenched-in fluorite-type material was annealed in air at 500 °C for up to 200 h. The decay in conductivity ( σ ) during annealing was measured using the procedure described by Webster et al (2008).…”

“…Pb 2+ was shown to occupy face-centred positions of the fluorite-type structure. In another work, annealing at 500 and 600 °C resulted in various symmetry-lowering phase transformations, with associated decays in conductivity (Webster et al , 2008). For example, the materials with composition (BiO 1.5 ) 0.80 (ErO 1.5 ) 0.20− x (PbO) x ( x = 0.03, 0.06, and 0.09) underwent a fluorite- to β -Bi 2 O 3 -type tetragonal transformation during annealing at 500 °C.…”

Defect structure in δ-Bi5PbY2O11.5

“…19 However, in ternary systems such as Bi 2 O 3 -MO x -PbO (M ¼ Ca, Y, Er and La), preservation of the d-type phase to room temperature is observed. [20][21][22][23][24] In a previous study we examined compositions in the Bi 2 O 3 -PbO-Y 2 O 3 system of general formula Bi 2.5+x Pb 0.5 YO 5.75+3x/2 (x ¼ 0, 1 and 2), which showed the d-phase structure. 12 These phases exhibited very high conductivities (ca.…”

Conductivity in lead substituted bismuth yttrate fluorites

“…Despite these apparent similarities the cubic δ-phase in the Bi 2 O 3 -PbO binary system is only observed at elevated temperatures [24]. However, in ternary systems of the type Bi 2 O 3 -MO x -PbO (M = Ca, Y, Er and La) it has been shown that δ-type phases can be preserved to room temperature [25][26][27][28][29][30].…”