Preparation of Yttria-Stabilized Zirconia by the Reverse Microemulsion Method and the Effect of Sc and Ce Doping on Microstructure and Ionic Conductivity for Solid Oxide Fuel Cell Applications

In this study, 8 mol% yttria-stabilized zirconia (8YSZ), ceria-, and scandia-doped YSZ powders were synthesized by the reverse microemulsion method. The powders were calcined at 1000 degrees C and sintered at 1450 degrees C. The crystalline properties and microstructure of the samples were characterized by X-ray diffraction and SEM methods, respectively. Oxygen ionic conductivities of the samples were measured by electrochemical impedance spectroscopy in the temperature range 250-375 degrees C. Grain interior and grain boundary resistivities were also calculated. Particle sizes of YSZ and Sc-doped YSZ were found to be < 100 nm, while that of Ce-doped YSZ was 120-150 nm. Approximately 1 mu m grains were observed after sintering of YSZ at 1450 degrees C. Particularly, the grain boundary and also the grain interior resistivities decreased with 3% scandia-doped YSZ. It was observed that the total conductivity of 3YSZ was higher than that of 3% ceria-doped YSZ

Preparation and characterization of Ca-Sm-Ce mixed oxides via cellulose templating method for solid oxide fuel cell applications

SmxCa0.2 xCe0.8Oy materials are synthesized by changing mol ratios of the composition as x &frac14; 0, 0.05, 0.1, 0.15 and 0.2, respectively, with a fast and facile cellulose templating method for the ? rst time. Micro- structures of the calcined and sintered samples are characterized by XRD and SEM-EDX. Density measurements are actualized by using Archimedes method. The electrical conductivity of the samples is obtained from two-probe impedance spectroscopy. Maximum solubility limit of CaO in CeO2 is found to be 9.4 mol% from the XRD results. Incorporation of CaO slightly increases the sinterability of the samples. It is observed that Sm&thorn; 3 expands the CeO2 lattice more than Ca&thorn; 2. 10 mol% CaO incorporated sample show the highest total conductivity with the value of 0.032 S cm 1 at 800 C. Obtained results show that Sm0.1Ca0.1Ce0.8Oy can be an excellent candidate for intermediate temperature solid oxide fuel cell applications due to its lower cost and higher performance compared to Sm0.2Ce0.8Oy at 800 C. Addi- tionally, cellulose templating method can be used as an effective method in order to prepare mixed oxide structures since the performances of the samples are higher than the samples which are prepared by more complex or costly hydrothermal and co-precipitation methods in literature

Synthesis, Spectral Characterization and Antimicrobial Activity of Some Transition Metal Complexes of 1,3-Bis(1H-benzimidazol-2-yl)-2-oxapropane

1,3-Bis(1H-benzimidazol-2-yl)-2-oxapropane (L) complexes with Fe(NO3)(3), CoCl2, Co(NO3)(2), Ni(NO3)(2), CuCl2, Cu(ClO4)(2), PdCl2, CdI2, Hg(NO3)(2) were synthesized and characterized by elemental analysis, molar conductivity, magnetic moment, TGA, FT-IR, NMR, ESI-MS, fluorescence spectroscopy. Also, the crystal structure of 1,3-bis(1H-benzimidazol-2-yl)-2- oxapropane] dichlorocobalt(II), [Co(L)Cl-2], complex is reported that it has distorted trigonal bipyramidal geometry. Antibacterial activities of the compounds were evaluated using the disk diffusion method against six bacteria and Candida albicans. The Hg(II) complex shows superior activity toward S. epidermidis and E. coli whereas the other complexes are ineffective except the Co(NO3)(2) complex: it showed weak activity toward all of the microorganisms