Nanoparticles with their specific properties newly have drawn a great deal of attention of researchers [1-3]Yttrium iron Garnet magnetic nanoparticles (YIG-NPs) are promising materials with novel applications in microwave, spintronics, magnonics, and magneto-optical devices.However, achieving stable and remarkable magnetic YIG-NPs has been remaining as a great challenge. In this paper, synthesized YIG-NPs by modifying co-precipitation (MCP) method is reported. Structural and magnetic properties of final products are compared to those of the materials prepared by citrate-nitrate (CN) method. Smaller crystals and particle size have been found by MCP method comparing to that of synthesized by CN method. Using a relatively low annealing temperatures for both sets of samples (~700 °C), the final YIG samples prepared by MCP method show more structural purity than those made by CN method. Higher saturation magnetization (M s ) and lower coercivity (H c ) are observed in MCP YIG sample (23.23 emu/g and 30.1 Oe) than the CN prepared YIG sample (16.43 emu/g and 44.95 Oe). The Curie temperature is measured to be 569 °C for the MCP YIG sample determined from set of M s measurement at different temperatures ranging from 80-600 K. These findings lead to significant improvement in quality of synthesized (synthetic methods) of YIG-NPs.

In recent years, multi-phase materials capable of multi-ion transport have emerged as attractive candidates for a variety of electrochemical devices. Here, we provide experimental results for fabricating a composite electrolyte made up of a one-dimensional fast sodium-ion conductor, sodium zirconogallate, and an oxygen-ion conductor, yttria-stabilized zirconia. The composite is synthesized through a vapor phase conversion mechanism, and the kinetics of this process are discussed in detail. The samples are characterized using diffraction, electron microscopy, and electrochemical impedance spectroscopy techniques. Samples with a finer grain structure exhibit higher kinetic rates due to larger three-phase boundaries (TPBs) per unit area. The total conductivity is fitted to an Arrhenius type equation with activation energies ranging from 0.23 eV at temperatures below 550 °C to 1.07 eV above 550 °C. The electrochemical performance of multi-phase multi-species, mixed sodium- and oxygen-ion conductors, is tested under both oxygen chemical potential gradient as well as sodium chemical potential gradient, before and after reaching equilibrium, are discussed using the Goldman-Hodgkin-Kats (GHK) and the Nernst equation. The total conductivity of the degraded cathode and anode terminals is investigated using electrochemical impedance spectroscopy. The degradation investigation of samples indicates a decrease in conductivity adjacent to the anode terminal, the loss of sodium content, and the formation of β-gallia adjacent to the fuel electrode after ~396h at 1463 K.

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The crystallization and magnetic behavior of yttrium iron garnet (YIG) prepared by metalloorganic decomposition (MOD) method are discussed. The chemistry and physics related to synthesis of iron and yttrium carboxylates based on 2-ethylhexanoic acid (2EHA) are studied, since no literature was found which elucidates synthesis of metallo-organic precursor of YIG in spite of the literatures of doped YIG samples such as Bi-YIG. Typically, the metal carboxylates used in preparation of ceramic oxide materials are 2-ethylhexanoate (2EH) solvents. Herein, the synthesis, thermal behavior and solubility of yttrium and iron 2EH used in synthesis of YIG powder by MOD are reported. The crystallization and magnetic parameters, including saturation magnetization and coercivity of these samples, smoothly change as a function of the annealing temperature. It is observed that high sintering temperature of 1300 to 1400 °C promotes the diffraction peaks of YIG, therefore, we can conclude that the formation of YIG in MOD method increases the crystallization temperature. The maximum value of saturation magnetization and minimum value of coercivity and remanence are observed for the sample sintered at 1200°C which are 13.7 emu/g, 10.38 Oe and 1.5 emu/g, respectively. This study cites the drawbacks in chemical synthesis of metallo-organic based YIG production. 2

Samples of 6 mol% Sc2O3- 1 mol% CeO2 co-doped ZrO2 were fabricated by conventional ceramic processing methods and sintered at various temperatures from 1000 °C to 1650 °C in air. The sintering conditions on microstructure and phase content are investigated using various characterization methods, including pycnometry, diffraction, and spectroscopy. The electrical conductivity of samples was investigated using electrochemical impedance spectroscopy (EIS). The effect of inductive load (measured from room temperature to 800 °C) is discussed in low to high-temperature regimes. At T<400 °C since the arc is not a complete semicircle, the high-frequency arc could be fit using a constant phase element (CPE), while by subtraction of inductive load, a good fit is achieved using a capacitor element instead of CPE. The Arrhenius conductivity plot of samples reveals that the specimen sintered at 1600 °C for 6 hours exhibits the highest conductivity. The activation energy (Ea) and conductivity pre-exponential (σ0) factor are calculated from a linear fit to data that decreases by the increase in sintering temperature.