РОССИЙСКАЯ АКАДЕМИЯ НАУК
УРАЛЬСКОЕ ОТДЕЛЕНИЕ
УРАЛЬСКОЕ ОТДЕЛЕНИЕ
ИНСТИТУТ ХИМИИ TBEPДОГО ТЕЛА
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РОССИЙСКАЯ АКАДЕМИЯ НАУК УРАЛЬСКОЕ ОТДЕЛЕНИЕ ИНСТИТУТ ХИМИИ TBEPДОГО ТЕЛА |
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| 21.01.2010 |
 
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Fig. 1. XRD patterns of (a) as synthesized (Pr0.75Sr0.25)0.95Cr0.5Mn0.5O3 − δ (b) reduced (Pr0.75Sr0.25)0.95Cr0.5Mn0.5O3 − δ in wet 5%H2. Peaks due to impurities in mounting are marked with circle. Fig. 2. (a) Selected area diffraction pattern of (Pr0.75Sr0.25)0.95Cr0.5Mn0.5O3 − δ from [īı0] direction (b) original image taken with the Gatan multi-scan CCD with 2-fold superlattice clearly in evidence (c) IFFT of the same image after masking, this shows an enhanced image with the strong superlattice fringes clearly shown. Fig. 3. XRD pattern of 1:1 mixture of (Pr0.75Sr0.25)0.95Cr0.5Mn0.5O3 − δ+ 8YSZ fired at 1300 °C, Peaks due to impurities in mounting are marked with circle. Fig. 5. TG analysis of Pr0.75Sr0.25Cr0.5Mn0.5O3 − δ (a) reduction in 5%H2 (b) oxidation in air. The sample was heated to 900 °C in 5%H2/Ar, dwelled for 2 h and cooled to room temperature in the same atmosphere followed by further heating to 900 °C in air, dwelling (2 h) and cooling to room temperature in air. Fig. 6. Total conductivity of Pr0.75Sr0.25Cr0.5Mn0.5O3 − δ in air and 5% H2 at different temperatures. Fig. 7. Isothermal conductivity vs. Po2 for Pr0.75Sr0.25Cr0.5Mn0.5O3 − δ at 900 °C, dashed line shows log Po2 1/8 slope dependence. Fig. 8. The anode polarization impedance of (Pr0.75Sr0.25)0.95Cr0.5Mn0.5O3 − δ anode in wet 5% H2 at different temperatures. Fig. 9. The anode polarization impedance of (Pr0.75Sr0.25)0.95Cr0.5Mn0.5O3 − δ anode in wet CH4 at different temperatures. Fig. 10. Fuel cell performance of graded (Pr0.75Sr0.25)0.95Cr0.5Mn0.5O3 − δ anode in wet 5%H2 at different temperatures. Fig. 11. Fuel cell performance of graded (Pr0.75Sr0.25)0.95Cr0.5Mn0.5O3 − δ anode in wet 5%H2, wet H2 and wet CH4 at 910 °C.
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75% dense Pr0.75Sr0.25Cr0.5Mn0.5O3 − δ at 900 °C in air and 5% H2/Ar are 9.6 and 0.14 S cm− 1 respectively. The conductivity of PSCM drops with decreasing Po2 and is a p-type conductor at all studied Po2. The average TEC of Pr0.75Sr0.25Cr0.5Mn0.5O3 − δ is 9.3 × 10− 6 K− 1, in the temperature range of 100–900 °C and is close to that of YSZ electrolyte. The anode polarization resistance of PSCM in wet 5%H2 is 1.31 Ω cm2 at 910 °C and in wet CH4 at 930 °C; the polarization resistance is 1.29 Ω cm2. PSCM was unstable at 900 °C in unhumidified hydrogen. Cell performance measurements carried out using graded PSCM and La0.8Sr0.2MnO3 as anode and cathode respectively yielded a maximum power density of 0.18 W cm− 2 in wet 5%H2/Ar at 910 °C and the corresponding current density was 0.44 A cm− 2 at 0.4 V. The activation energy for the electrochemical cell operating in wet (3% H2O) 5%H2/Ar fuel is 85 kJ mol− 1.
