New silicon substituted BiMeVO : synthesis and study of structural properties in relation to ionic conductivity

Area of Science:

• Solid-state chemistry
• Materials science
• Electrochemistry

Background:

• Aurivillius compounds, specifically Bi4V2O11, are known for their potential as solid electrolytes.
• Partial substitution of elements can significantly alter the structural and electrical properties of these materials.

Purpose of the Study:

• To investigate the effect of silicon (Si) substitution for vanadium (V) in Bi4V2O11 on its crystal structure and ionic conductivity.
• To identify the optimal Si content for enhanced ionic conductivity in this solid solution system.

Main Methods:

• Synthesis of a series of solid solutions Bi4V(2-x)SixO11-y with varying Si content (0 ≤ x ≤ 0.4).
• X-ray diffraction (XRD) to determine the crystal structure and phase identification of the synthesized compounds.
• Electrochemical Impedance Spectroscopy (EIS) to measure the ionic conductivity of the ceramic samples.

Main Results:

• Formation of a solid solution Bi4V(2-x)SixO11-y.
• Identification of different polymorphic forms: monoclinic α-form (x=0.1), orthorhombic β-polymorphs (x=0.2, 0.3), and tetrahedral γ-polymorph (x=0.35).
• The ceramic sample with x=0.1 demonstrated the highest ionic conductivity.

Conclusions:

• Partial substitution of vanadium with silicon in Bi4V2O11 creates a solid solution with distinct polymorphic phases.
• Silicon doping at x=0.1 in Bi4V2O11 significantly enhances ionic conductivity, highlighting its potential for solid electrolyte applications.