Phosphorus-substitution effect on the phase stabilization, electrical and spectroscopic properties of LAMOX-based electrolyte for solid oxide fuel cells

Noureddine Mhadhbi; Wiem Jabeur; Ahlem Guesmi; Ammar Houas; Naoufel Ben Hamadi; Houcine Naïli

doi:10.1039/d3ra04777f

Phosphorus-substitution effect on the phase stabilization, electrical and spectroscopic properties of LAMOX-based electrolyte for solid oxide fuel cells

RSC Adv. 2023 Oct 16;13(43):30168-30175. doi: 10.1039/d3ra04777f. eCollection 2023 Oct 11.

Authors

Noureddine Mhadhbi^{1

2}, Wiem Jabeur¹, Ahlem Guesmi³, Ammar Houas⁴, Naoufel Ben Hamadi³, Houcine Naïli¹

Affiliations

¹ Laboratory Physico Chemistry of the Solid State, Department of Chemistry, Faculty of Sciences, University of Sfax BP 1171 Sfax 3000 Tunisia [email protected].
² University of Monastir, Preparatory Institute for Engineering Studies of Monastir Monastir 5019 Tunisia.
³ Chemistry Department, College of Science, IMSIU (Imam Mohammad Ibn Saud Islamic University) P.O. Box 5701 Riyadh 11432 Saudi Arabia.
⁴ Research Laboratory of Catalysis and Materials for Environment and Processes, University of Gabes City Riadh Zerig Gabes 6029 Tunisia.

Abstract

A series of P⁵⁺ - doped La₂Mo₂O₉ phases with different concentrations of P⁵⁺ were prepared using conventional solid-state reactions. The formation of phase-pure P⁵⁺-doped La₂Mo₂O₉ has been monitored by powder X-ray diffraction, thermal analysis, conductivity measurements, Raman, and FT-IR absorption techniques. The structure and lattice parameters of La₂Mo_2-yP_yO_9-y/2 are obtained from Rietveld refinement. The effect of substituting P for Mo reveals that the phase transition which occurs in La₂Mo₂O₉ around 560 °C disappears when y > 0.02, as demonstrated by thermal analysis. Pure P⁵⁺-doped phases with monoclinic structure (α-form, the space group P2₁) were observed for the concentration of optically active ions up to y = 0.02. When the concentration of P⁵⁺ ions is higher, a cubic structure (β-form, the space group P2₁3) starts to appear. However, up to the concentration of y = 0.03 of the P⁵⁺ ion a mixture of the monoclinic and cubic phases has been observed. From infrared and Raman analysis it is confirmed that different vibration modes arise from the vibration of molybdenum-oxygen bands. Mo-O bond lengths are also found to be independent of P-doping.