Structure and Mixed Proton-Electronic Conductivity in Pr and Nb-Substituted La5.4MoO12-δ Ceramics
Abraham Sánchez-Caballero1, José M Porras-Vázquez1, Lucía Dos Santos-Gómez1
1Departamento de Química Inorgánica, Cristalografía y Mineralogía, Universidad de Málaga, 29071 Málaga, Spain.
Materials (Basel, Switzerland)
|February 13, 2025
Summary
This study explores how Praseodymium (Pr) content and Niobium (Nb) doping affect lanthanide molybdates
Area of Science:
- Solid-state chemistry
- Materials science
- Electrochemistry
Background:
- Lanthanide molybdates exhibit mixed proton-ionic conductivity, crucial for electrochemical applications.
- Optimizing conductivity requires understanding the interplay between material composition and structure.
Purpose of the Study:
- To investigate the impact of Praseodymium (Pr) content and Niobium (Nb) doping on the crystal structure and electrical properties of La$_{5.4-x}$Pr$_{x}$Mo$_{1-y}$Nb$_{y}$O$_{12-δ}$.
- To enhance electronic conductivity via Pr$^{4+}$/Pr$^{3+}$ redox pairs and ionic conductivity through Nb$^{5+}$ doping.
Main Methods:
- Materials characterization using X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission and scanning electron microscopy (TEM and SEM).
- Electrical property evaluation via complex impedance spectroscopy.
Main Results:
- Crystal structure transitions from rhombohedral (low Pr) to cubic fluorite-type (high Pr).
- Complex nanodomain structures and incommensurate modulations observed via TEM.
- Highest conductivity (204.4 mS cm$^{-1}$ at 700 °C in N$_{2}$) achieved with high Pr content, attributed to Pr$^{4+}$/Pr$^{3+}$ redox mediation.
Conclusions:
- Pr content significantly influences the crystal structure and conductivity of lanthanide molybdates.
- Tailored doping strategies, particularly with Pr and Nb, can optimize electronic and ionic conductivity.
- These materials show promise for high-temperature electrochemical applications.
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