Akademik Veri Yönetim Sistemi
IV. BASKENT INTERNATIONAL CONFERENCE ON MULTIDISCIPLINARY STUDIES, Ankara, Türkiye, 4 - 06 Ağustos 2023, ss.61-62
Due to its superior ion conductivity, face–centered cubic–Bi2O3 (δ–phase) material has been recognized
as suitable solid electrolytes in terms of the Intermediate Temperature–Solid Oxide Fuel Cells (IT–
SOFCs) applications. Interestingly, the highest conductivity values reported for cubic–stabilized Bi2O3
electrolytes have been achieved by employing the double doping approach, relying on co–dopant
content ratios of 2:1 or 1:2. In the present study, ceramic compositions of Bi2O3 co–doped with Tm–
Yb rare earths have been developed using solid–state techniques. For stability of δ–phase, all
compositions were then subjected to heat treatment at 750 °C for 100 hours. Annealed samples were
characterized by several experimental studies including X–Ray Diffraction (XRD), Termogravimetric
and Diffeantial Thermal Analysis (TG & DTA), Four Point Probe Technique (FPPT), And Field
Emission–Scanning Electron Microscope (FE–SEM). The conductivity of sample 8Tm4Yb created
using a content ratio of 2:1 is 0.432 S/cm at 700 °C, outperforming that of single–doped 20ESB
electrolytes. Arrhenius plots of conductivity in Tm–rich materials also showed that it increased with
doping rate, reflecting an increase in oxygen–unoccupied concentration. In many samples, the order–
disorder transitions (ODT) and phase transition (α→δ) were clearly apparent on DTA curves and
Arrhenius plots. The FE–SEM images of the Tm–rich samples revealed a reduction in particle size with doping, which was directly related to the lattice strain caused by doping. Additionally, surface holes
were visible in FE–SEM images of Tb–rich samples, which could result in a decline in electrical
conductivity.
Keywords: Phase transition, Ion conductivity, Unit cell contraction, Electrical activation energy,
Average crystal size.