Development of Novel Fe-Doped Barium Calcium Niobates as Promising Mixed Conductors for Solid Oxide Fuel Cells (SOFCs)

Abstract

Synthesis, structural analysis, chemical stabilities and electrochemical measurements of a new Fe-doped barium calcium niobates (Fe-BCNs) family as promising mixed conductors for SOFCs were reported. The Fe-BCNs, prepared by conventional solid state method, exhibited as single phases which can be indexed as Fm-3m (space group no. 225) structure with cell parameter a ~ 8.4 Aå by PXRD and SAED. The Fe-BCNs showed superior chemical stability in pure CO2 gas at 800oC for 24 h, boiling H2O for 72 h, 30 ppm H2S at 600oC for 24 h and pure CH4 gas at 600oC for 12 h, confirmed by PXRD. The highest total conductivity of 1.3 × 10-2 Scm-1 (Ea~0.5eV) was found for Ba2Ca0.787Fe0.566Nb0.646O6-δ at 400oC in air.

Studies on Polymorphic Sequence during the Formation of the 1:1 Ordered Perovskite-Type BaCa0.335M0.165Nb0.5O3-δ (M = Mn, Fe, Co) Using in Situ and ex Situ Powder X-ray Diffraction

“…Similarly, many Bsite-doped Ba 3 Ca 1+x−y Nb 2−x−z M y+z O 9-δ (M = Ti, Mn, Fe, Co, Zn, Ta, Ce) samples were revealed to have the B-site 1:1 ordered perovskite-type structure. [19][20][21][22][23][24]31 The above samples were all sintered at an elevated temperature range of 1300− 1500 °C in air.…”

Effect of substitution of B-sites by Mn, Fe and Co in double perovskite-type Ba3CaNb2O9 on structure and electrical properties

“…Ti, Zn, Fe, K, Ta and Ce-doped BCN known to form 1 : 1 ordered cubic perovskite structure. [20][21][22][23]27,28 The PXRD patterns of the as-prepared transition metal ions-doped BCN could all be indexed as 1 : 1 B-site ordered double perovskitetype structure, except for Ba 2 Ca 0.79 Nb 0.71 M 0.5 O 6Àd (M ¼ Mn, Co). Small amount of simple-perovskite phase was detected in addition to the main double-perovskite phase.…”

“…The presence of the low-frequency intercepts on Z 0 suggests the non-blocking at the electrode and material interface. 26,27,[35][36][37] The Arrhenius plots for the total conductivities of Ba 2 Ca (1ÀxÀy) M (x+z) Nb (1Àz+y) O 6Àd in air, H 2 , 3% H 2 O in air and 3% H 2 O in H 2 are shown in Fig. 6.…”

Synthesis and characterization of perovskite-type BaMg0.33Nb0.67−xFexO3−δ for potential high temperature CO2 sensors application

“…Nb 5+ in BMN is reported to provide robustness to the pellet and signicant substitution of Nb with Fe unsurprisingly resulted in mechanical instability. 17 In addition, with the introduction of Fe, BMNF samples melt at high sintering temperature (1400 C); therefore, we reduced the sintering temperature for BMNFs to 1300 C and BMN was sintered at 1400 C. EDX measurement on these samples revealed the expected stoichiometry based on the initial preparation condition excluding any possible evaporation of Ba or Fe during sintering (see ESI: Table S1 †).…”