Characterization of Y-Doped SrTi1-XVxO3 (Y = 0.1, x = 0.1 and 0.2) Anodes for SOFCs
In this research, the effect of substitution of A and B site of the STO perovskite was investigated using Y-doped SrTi1-xVxO3 with compositions Sr0.9 Y0.1 Ti0.9 V0.1 O3 and Sr0.9 Y0.1 Ti0.8 V0.2 O3. Both samples were prepared using solid state synthesis reaction sintered at temperature of 1450°C and 1250°C for duration of 4 hrs for Sr0.9 Y0.1 Ti0.9 V0.1 O3 and Sr0.9 Y0.1 Ti0.8 V0.2 O3, respectively. The microstructures of the samples were analyzed using scanning electron microscope (SEM) and the porous structure of the materials fulfills the essential characteristic as anode materials. X-ray diffraction (XRD) analysis of the materials confirmed that both samples formed single phase tetragonal structure (space group: I 4/m c m).
The thermal expansion coefficient (TEC) values of the samples are closed to the reported value of yttrium stabilized zirconia (YSZ) which show good thermomechanical compatibility of the materials with YSZ(TEC~ 10.8 x 10-6 K-1) . Figure 1 illustrates the effect of TEC values with increasing B site doping concentration.
The electronic conductivity of the samples was measured under normal atmospheric pressure using four probe DC techniques at a temperature range of between 500°C to 1000°C. The measured conductivity of the samples is within the range of 0.0032 Scm-1 to 0.2042 Scm-1which is considered to be very low. The Arrhenius plot of the samples is shown in figure 2 below.
The average zeta potential of the samples is within the range of moderate stability of colloidal suspension with measured values of -29.9 mV and -31.2 mV for Sr0.9 Y0.1 Ti0.9 V0.1 O3 and Sr0.9 Y0.1 Ti0.8 V0.2 O3respectively. This suggests that the materials are able to resists aggregation. Refer to Table 1 below for the interpretation of the zeta potential values .
TG analysis of the samples was plotted in figure 3 below. 18.81% decrease in weight was accounted for Sr0.9 Y0.1 Ti0.9 V0.1 O3 while an increase of 2.28% in weight was seen for Sr0.9 Y0.1 Ti0.8 V0.2 O3.
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