Synthesis, characterization, and structural analysis of (1-x) Eu2Ti2O7 – x ZnO solid solution with a pyrochlore structure: Insights for potential applications in hydrogen storage systems

Abstract

This study focuses on the synthesis and characterization of a (1-x) Eu2Ti2O7 – x ZnO solid solution with a pyrochlore structure using a solid-state method. The structural investigations of the prepared materials were carried out using powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR), and Raman spectroscopy. These techniques confirmed the successful formation of a new non-stoichiometric solid solution with a pyrochlore structure within the compositional range of 0 ≤ x ≤ 0.33, maintaining a cubic structure with the Fd-3m space group. A slight increase in the lattice parameter, a, was observed with higher substitution levels, x. Quantitative analysis using FullProf software revealed the substitution of Zn2+ ions on both Eu3+ and Ti4+ sites, with non-equivalent proportions, leading to vacancies in the anionic sublattice. Furthermore, the electrochemical hydrogen storage (EHS) capacity of these materials was examined. The pyrochlore solid solution with x = 0.25 exhibited an outstanding discharge capacity of about 1400 mAh/g, surpassing that of other samples. This finding highlights its high potential for hydrogen storage. Consequently, our research yields valuable insights into the synthesis, structural properties, and electrochemical performance of the (1-x) Eu2Ti2O7 – x ZnO solid solution, opening up new possibilities for hydrogen storage.