Abstract
In this study, Erbium and Ytterbium doped Bismuth based electrolyte was investigated for the solid oxide fuel cells. Yb
2
O
3
and Er
2
O
3
oxides were doped into the Bi
2
O
3
compound using solid-state reaction method in (Er
2
O
3
)
x
(Yb
2
O
3
)
y
(Bi
2
O
3
)
1-x–y
stoichiometric ratio (
x
= 2, 4, 6, 8 mol% and
y
= 5, 10, 15, 20 mol%). Investigations were carried out for 700 °C, 750 °C, 800 °C sintering temperatures, respectively. Structural characterization was carried out using X-ray powder diffraction (XRD), and stable face-centred cubic crystal phase (
δ
-phase) was successfully obtained in all samples containing more than 12 mol% dopant. When the variation of the lattice parameters according to the total addition rate is examined, it is observed that as the additive content increases, lattice parameters also become larger. Differential Thermal Analysis (DTA) showed that all samples were thermally stable and phase transformation was not observed below 1000 °C. The porosity of pellets was analysed from their surface images taken via Scanning Electron Microscopy (SEM), and these results showed an increase in porosity with increasing dopant content. Total conductivities of electrolytes were measured by Four-Point Probe technique (4PPT), and temperature dependency of conductivity was investigated. The single
δ
-phase ErYbSB-15 sample was found to have highest conductivity (~ 5 × 10
–2
Scm
−1
at 560 °C). This conductivity value is higher than the conductivity of 20 mol% Erbium doped bismuth oxide previously known as the highest conductivity value of doped Bismuth oxide based electroceramics given in the literature.
Graphical abstract
Synthesising of Er and Yb Doped Bismuth Oxide Solid Electrolytes