The effect of the sintering parameters on the structure and oxygen ion conductivity of Y2O3–ZrO2–CeO2 ceramics

Yttria and zirconia co-doped ceria ceramics is a promising material for solid electrolytes for intermediate-temperature solid oxide fuel cells (IT-SOFC). The ionic conductivity of ceramics significantly depends on Ce 3+admixture presence, which can be controlled by heat treatment regimes. In the current study we report the detailed electrochemical and structural study of 10Y2O3-30ZrO2-60CeO2 ceramics manufactured via two-step sintering approach. The effects of the second sintering step on the phase composition, homogeneity of components distribution, grain growth and the microstructures of ceramics wereinvestigated via XRD, SEM, Raman spectroscopy techniques. Special attention was paid to valence state of cerium ions, which was examined via XPS. Using impedance spectroscopy it was shown that ternary ceramics possesses ionic conductivity up to 2.09·10−3 S/cm at 973 ​K in the N2 atmosphere and at the residual oxygen partial pressure no more than 10−3 atm

One-Pot Synthesis of Silica-Coated Gold Nanostructures Loaded with Cyanine 5.5 for Cell Imaging by SERS Spectroscopy

Anisotropic gold nanoparticles have been recognized as promising agents for medical diagnostics and cancer therapy due to their wide functionality, photothermal effect, and ability for optical signal amplification in the near-infrared range. In this work, a simple and rapid method for the preparation of bone-shaped gold nanoparticles coated with a dye-impregnated silica shell with an aminated surface is proposed. The possibility of further functionalization the nanostructures with a delivery vector using folic acid as an example is demonstrated. The average size of the resulting tags does not exceed 70 nm, meeting the criteria of cell endocytosis. The prepared tags exhibit surface-enhanced Raman scattering (SERS) spectra at excitation with lasers of 632.8 and 785 nm. Cell imaging is performed on HeLa cells based on the most pronounced SERS bands as a tracking signal. The obtained images, along with scanning electron microscopy of cell samples, revealed the tendency of tags to agglomerate during endocytosis followed by the “hot spots” effect. To evaluate the toxic and proliferative effect of the nanotags, an MTT assay was performed with two HeLa and HEP G2 cell lines. The results revealed higher viability for HEP G2 cells

Electrochemical Characterization of Novel Polyantimonic-Acid-Based Proton Conductors for Low- and Intermediate-Temperature Fuel Cells

The development of novel proton-conducting membrane materials for electrochemical power units, i.e., low temperature fuel cells (FCs), efficiently working up to 300 C, is a critical problem related to the rapid shift to hydrogen energy. Polyantimonic acid (PAA) is characterized by high conductivity, sufficient thermal stability and can be regarded as a prospective proton-conducting material. However, the fabrication of bulk PAA-based membranes with high proton conductivity remains a challenging task. In the present work, for the first time, the authors report the investigation on proton conductivity of bulk PAA-based membranes in the temperature range 25–250 C, both in dry air and in moisturized air. Using PAA powder and fluoroplastic as a binder, fully dense cylindrical membranes were formed by cold uniaxial pressing. The structures of the PAA-based membranes were investigated by SEM, EDX, XRD and Raman techniques. STA coupled with in situ thermo-XRD analysis revealed that the obtained membranes corresponded with Sb2O5 3H2O with pyrochlore structure, and that no phase transitions took place up to 330 C. PAA-based membranes possess a high-grain component of conductivity, 5 10 2 S/cm. Grain boundary conductivities of 90PAA and 80PAA membranes increase with relative humidity content and their values change non-linearly in the range 25–250 C