Smita A. Acharya

Low-temperature SOFC operation promises better durability, lower costs, and faster start-up than conventional devices. The main barrier is reduced ionic conductivity at lower temperatures. Ceria-based electrolytes show potential, but single-dopant strategies stumble on one problem: dopant-vacancy associations trap oxygen ions and impede long-range transport. This work explores how Nd-doping changes the defect landscape in SDC. We synthesized Ce0.85Sm0.15-xNdxO2-δ using microwave-assisted-sol-gel combustion. Raman spectroscopy with spatial correlation modelling revealed that Nd content tunes the correlation length and defect concentration. High-temperature EXAFS identified temperature-dependent coordination shifts and showed vacancies organizing into dimer and trimer configurations. SNDC2 stood out with 1.45 × 10-3S/cm total conductivity at 550°C, activation energy of 0.85eV, and weaker vacancy-dopant binding than other compositions. A button cell with SNDC2 shows 0.45 W.cm⁻¹ power density at 550°C. Hebb-Wagner measurements yielded an ionic transference number of ~0.90. Nd doping offers practical way to engineer the defect landscape in SDC for LT-SOFC.

Polymer electrolyte membranes for PEMFCs often fail above 80 °C due to dehydration of hydrated polymers. We report anhydrous, high‑temperature PVA–PVP–SrCeO₃ composite membranes (0–20 wt% SCO) prepared by solution casting, with SCO synthesized via sol–gel combustion. The optimized PVA–PVP–SCO‑0.15 (15 wt% SCO) doped with phosphoric acid shows IEC = 0.287 meq g⁻¹ and proton conductivity 1.11×10⁻² S cm⁻¹ at 120 °C—an order‑of‑magnitude improvement over pristine PVA–PVP. XRD and FTIR indicate SCO‑induced amorphization and strengthened hydrogen‑bonding/dipolar interactions. SEM–EDAX shows uniform SCO dispersion at 15 wt%. EIS reveals reduced grain‑boundary resistance and activation energy ≈0.4 eV. Dielectric and modulus analyses show increased dielectric constant, faster relaxation (τ reduced from 4.47×10⁻⁵ to 0.56×10⁻⁵ s), and enhanced ion dissociation consistent with Grotthuss proton transport via SCO oxygen vacancies. Single‑cell tests at 120 °C (dry H₂/O₂) deliver 376 mW cm⁻² peak power, 2.25× higher than PVA–PVP, demonstrating competitive, low‑cost high‑temperature PEMFC membranes.

The novel electrolyte material, 8% sodium-doped tungsten oxide, i.e. Na0.08W0.92O3-d, is prepared by using the combustion synthesis method. X-ray diffraction study reveals that Na0.08W0.92O3-d has a single-phase monoclinic structure with the P21/n space group. A dense microstructure is observed by scanning electron microscope. The Na0.08W0.92O3-d material has been analyzed by using complex impedance spectroscopy to determine the ionic conductivity. The ionic conductivity is correlated with the microstructures of the electrolyte to interpret the transportation of oxygen ion through the material. Ionic conductivity reaches to a maximum value of 0.12 S/cm at 650 °C. This emphasizes that above novel electrolyte material will be a potential candidate for low temperature solid oxide fuel cell.

Flexible energy storage/energy harvester devices are crucial to cater to the energy needs of various forms of flexible products in advanced technology. Polymer–ceramics composite systems are recognized and extensively explored for the development of flexible devices for various applied fields. In this work, polyvinylidene fluoride (PVDF)–NaNbO ₃ composite flexible films are developed. Ceramic phase NaNbO ₃ is prepared by the hydrothermal synthesis method. The X‐ray diffraction, followed by Rietveld refinement, confirms a pure phase with an orthorhombic structure. The composite films are synthesized by the solution casting method in various compositions of PVDF:NaNbO ₃ (wt% 95:05, 90:10, 85:15, 80:20). Fourier transform infrared (FTIR) spectroscopy of all thin films is carried out to identify functional groups of the organic phase and corresponding deformation by the ceramic blend. Dielectric behavior in terms of dielectric constant and dissipation factor is investigated to justify its ability as an energy harvester. The ferroelectric behavior studied by the polarization‐electric (P‐E) loop tracer exhibits significant modulations in coercivity and remnant polarization. A prototype model of the energy harvesting system is fabricated, and its feasibility as an energy harvester is revealed by using a Digital storage oscilloscope. Weight% 0.85 PVDF–weight% 0.15 NaNbO ₃ composite systems have delivered around 9 V output voltage pulse just by using human figure pressure with V _rms 4.02 at applied load resistance 33 MΩ.