Unveiling conductive properties of La2Zr2O7 for solid oxide fuel cell applications

Abstract

Pyrochlore-type rare-earth ceramics (A₂B₂O₇) are promising candidates for energy storage and solid oxide fuel cell (SOFC) applications owing to their exceptional oxygen ion conductivity and low-loss energy storage capabilities. In this study, gadolinium (Gd)-doped lanthanum zirconates (La_2−xGd_xZr₂O₇) were synthesized via the WOWS (water–oil-water surfactant-assisted) sol–gel method to systematically investigate the effects of Gd³⁺ substitution on structural, electrical, and dielectric properties. X-ray diffraction (XRD) analysis revealed a doping-induced phase transition from pyrochlore (Py, space group Fd3m) to fluorite (F, Fm3m) symmetry, accompanied by a reduction in crystallite size (49 nm → 23 nm) and lattice constant (10.85 Å → 10.44 Å), confirming significant structural distortion.

Dielectric properties were modeled using a non-linear modified Debye function, revealing frequency-dependent dispersion consistent with Maxwell-Wagner interfacial polarization. Enhanced phase stability and conductivity at elevated temperatures (≥400 °C) underscore the potential of Gd-doped La₂Zr₂O₇ as an electrolyte material for intermediate-temperature SOFCs.