The Impact of Sintering Atmosphere and Temperature on the Phase Evolution of High Surface Area LSCF Prepared by In Situ Carbon Templating

Abstract

The thermochemical stability of lanthanum strontium cobalt ferrite (LSCF) processed between 1000 °C–1200 °C via the in situ carbon templating method was studied. This method generates high surface area ceramics at traditional solid oxide fuel cell (SOFC) sintering temperatures by generating a carbon template in situ and subsequently removing the template by oxidation at 700 °C. Argon processed samples produced an amorphous carbon template, whereas nitrogen tended to form graphitic carbon. Prior to the oxidation step, nitrogen samples comprised larger La2O3 crystallites (22–40 nm) compared to argon (9–17 nm). Upon oxidation, argon samples resulted in a pure LSCF phase with surface areas in the 21–29 m2·g−1 range, whereas nitrogen samples contained significant impurities. This demonstrates that the size of La2O3 crystallites formed during inert processing limited the ability to produce a pure LSCF phase. Symmetrical cells comprising nano-LSCF electrodes generated by the templating method were compared to cells sintered directly in air. Impedance results suggest that nano-LSCF cells and cells processed in air were dominated by interfacial charge transfer resistance and gas diffusion, respectively. The results map out conditions for preparing and integrating high surface area, nanostructured LSCF into SOFC electrodes at traditional sintering temperatures. Strategies for improving the interfacial resistance of nano-LSCF electrodes are discussed.

Crystallographic characterization and application of copper doped hydroxyapatite as a biomaterial

“…The mathematical expression is given below in eqn (16). 43 Here, in eqn (16), RI s refers to the standard relative intensity of the same plane. The calculated values of relative intensities were 0.17 (HAp), 0.19 (5 Cu HAp) and 0.25 (10 Cu HAp) and the preference growth was 0.07, 0.21 and 0.58 for the prepared samples, respectively.…”

Modification of the crystallographic parameters in a biomaterial employing a series of gamma radiation doses

“…The relative intensity of the (002) plane was calculated from the ratio of the intensity of the (002) plane to the intensities of the three strongest peaks such as (121), (112), and (003) according to ICDD card no: # 01-074-0565. Mathematically the relative intensity (RI) can be expressed as eqn (13): 9 where the subscript denotes the respective plane considering the intensity count. Considering the relative intensities of ICDD card no: # 01-074-0565, the relative intensity for the (002) plane was calculated to be around 0.188.…”

“…The relative intensity of the (002) plane was calculated from the ratio of the intensity of the (002) plane to the intensities of the three strongest peaks such as (121), (112), and (003) according to ICDD card no: # 01-074-0565. Mathematically the relative intensity (RI) can be expressed as eqn (13): 9…”

“…Most of the researchers have been concentrating on only the crystallite size of materials due to the larger surface area. [8][9][10][11] Other crystallographic properties are very significant in materials' applicability. Various reaction parameters are the controlling factors of nano-material synthesis such as reagent concentration, 12 temperature and ripening time, 13 pH, 14 etc.…”

Lowering the Impedance of Lanthanum Strontium Manganite-Based Electrodes with Lanthanum Oxychloride and Lanthanum Scavenging Chloride Salts

“…The nano-YSZ was generated by a novel processing technique referred to as in situ carbon templating. [11][12][13][14][15][16] The processing method involves heating an inorganic-organic hybrid material containing zirconium and yttrium in an inert atmosphere, forming YSZ nanoparticles embedded in amorphous carbon. Subsequently, the amorphous carbon is burned off at a low temperature, 550 °C-700 °C, leaving behind the YSZ nanoparticles.…”