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In this research work, BaZr0.85Ho0.10Y0.025Nd0.025O3-δ (BZHYN) electrolyte ceramic was synthesized through a cost-effective flash pyrolysis route followed by conventional sintering for intermediate-temperature solid oxide fuel cells. The calcined powder and sintered pellet were characterized through various techniques like high-resolution X-ray diffraction (HRXRD), high-resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectra (EDS), and Raman spectroscopy. The HRXRD pattern of calcined and sintered pellet shows the pure cubic phase with P m 3 ¯ m space group symmetry through the Rietveld refinement. The study of the electron-density distribution of calcined powder and sintered pellet calculated by the maximum entropy method reveals the presence of oxygen vacancies at the octahedral site in the sintered sample. The microstructure of the fracture surface of the sintered sample indicates two types of grain with a relative density of 93.7% through FESEM. The Raman analysis confirms the distortion along the c-axis and oxygen vacancies in the octahedral site of BZHYN ceramic. Impedance spectroscopy measurement was conducted in the temperature range of 50 to 700 °C and frequency range of 1 Hz to 10 MHz. The Nyquist plots obtained in the temperature range of 350–700 °C reveal three distinct relaxation processes attributed to grain, grain boundary, and electrode effect. The temperature-dependent exponent (n) associated with grain and grain boundary decreases with the increase in temperature, indicating that large polaron hopping is involved in the electrical conduction mechanism. [ABSTRACT FROM AUTHOR]

Solid biopolymer electrolytes based on potato starch (PS), sodium iodide (NaI), and dispersed with cobalt ferrite (CoFe2O4) as ceramic nanofillers were synthesized via a solution casting technique. These synthesized solid biopolymer electrolytes have been characterized by electrical impedance spectroscopy (EIS), Fourier transform infrared (FTIR) spectroscopy, FTIR deconvolution technique, dielectric studies, linear sweep voltammetry (LSV), and cyclic voltammetry (CV). The highest conductivity is found to be 8.13 × 10–3 S/cm for the system containing 1.0 wt.% of CoFe2O4 nanofillers. The ceramic nanofillers enhance the ion motion inside the polymer matrix, leads to increase the electrolyte's conductivity. FTIR confirmed that the polymer, NaI salt, and ceramic nanofiller interact with each other appreciably, and formed the complexation between the polymer, NaI salt, and ceramic nanofillers. The ion transport parameters such as mobility (µ), carrier density (n), and diffusion coefficient (D) were determined from the deconvolution of FTIR spectra and further used to compute the free ions and contact ion pairs in the solid biopolymer electrolytes. LSV and CV measurements indicate that the synthesized solid biopolymer electrolytes have a great potential in the electrochemical devices. The electrochemical stability window of the material (PNGC-1.0) is 2.5 V, and CV measurement shows the absence of any redox peaks, which may be a promising electrolyte for supercapacitor applications. [ABSTRACT FROM AUTHOR]

In the present research work, La0.5Sr0.5Bi0.2Co0.4Fe0.4O3-δ cathode ceramic powder is synthesized through cost-effective flash pyrolysis process and followed by conventional sintering for IT-SOFCs. The Rietveld refinement program is used to determine the crystal structure, unit cell parameters and bond length. The XRD result indicates existence of a pure single phase of rhombohedral structure with R3 °C space group symmetry detected from the sample sintered at 700 °C. FESEM micrographs of fracture surface of sample sintered at 700 °C showed a high porosity and nano grain sizes (50-100 nm). Combined impedance and electric modulus spectroscopic are used to investigate the relaxation phenomena in La0.5Sr0.5Bi0.2Co0.4Fe0.4O3-δ ceramic over a broad range of temperature and frequency. A single relaxation peak is observed in the imaginary part of impedance and electric modulus spectra, which could be due to the contribution of grain boundary of La0.5Sr0.5Bi0.2Co0.4Fe0.4O3-δ ceramic. The imaginary part of modulus (M") spectra is studied with help of non-exponential decay function or Kohlrausch-Williams-Watts (KWW) parameter (ß). In the combined plot of the imaginary part of impedance (Z") and electric modulus (M") spectra at 210 °C, only a single peak of Z" and M" is observed at the same frequency which specifies that the conduction process is a long-range motion of the charge carriers. The frequencydependent conductivity is followed by the Jonscher's double power law in the temperature range 30-210 °C. [ABSTRACT FROM AUTHOR]

In the present work, the proton-conducting BaZrO3 (BZO) ceramics powder was synthesized by cost-effective flash pyrolysis route followed by conventional sintering. The structural analysis (crystal symmetry and unit cell parameters) of X-ray diffraction (XRD) pattern using Rietveld refinement method was investigated systematically under the influence of different temperature. The XRD results indicate that a single phase with Pm3¯m space group symmetry obtained from all the calcined and sintered samples. The fractured surface of the sample sintered at 1600 °C for 8 h showed a high degree of densification with fairly large uniform grain sizes (4-6 μm) through FESEM analysis. The impedance and electric modulus spectroscopic studies of the sample were evaluated over broad temperature (250-700 °C) and frequency (1 Hz-10 MHz) ranges. Two types of relaxation signatures were distinguished from the above study, which could be associated with the contribution from grain interior and grain boundary of BZO ceramics. Furthermore, the Kohlrausch-Williams-Watts parameter (β) corresponding to grain interior (bulk) and grain boundary indicates that its deviation towards the ideal Debye behavior as the temperature increases. The total electrical conductivity of sample was detected to be 1.0 × 10−5 S cm−1 at 700 °C under 3% humidified atmospheric condition, which is one order higher magnitude than that measured in air. [ABSTRACT FROM AUTHOR]

The MgAl2O4 nanocrystalline powder was synthesized using naturally available egg white and inexpensive metal nitrate salts. During this process, the freshly extracted egg white was mixed with metal nitrate salt and subsequently heated at 350 °C in a pit furnace. The entire dehydration of the aqueous solution thus facilitates the low-density fluffy mass. From TGDTG results, it was observed that maximum decomposition of the precursors occurred below 600 °C. Therefore, the calcination temperature of as-synthesized powder was set at 600 °C. The MgAl2O4 bulk ceramic foam was fabricated by dispersing different loading of MgAl2O4 nanoparticles in the egg white, and then coating on polyurethane sponge prior to drying and sintering at a higher temperature. The ceramic suspensions exhibit a typical shear thinning behavior, and its viscosity was found to be significantly influenced by MgAl2O4 powder content. An optimum loading of 40 wt% MgAl2O4 nanoparticles in the egg white was found to show maximum porosity up to 90%. The obtained ceramic foam has potential applications in catalysis, absorption and sensor. [ABSTRACT FROM AUTHOR]