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Thermal Evolution and Phase Transitions in Electrochemically Activated Sc2(MoO4)3
1School of Chemistry , UNSW Sydney , Sydney NSW 2052 , Australia.
Inorganic Chemistry
|July 25, 2019
Summary
Electrochemical activation of Scandium Molybdate (Sc₂(MoO₄)₃) with lithium, sodium, and potassium creates new phases with altered thermal expansion properties. This process unlocks diverse material compositions for potential applications.
Area of Science:
- Materials Science
- Solid-State Chemistry
- Electrochemistry
Background:
- Scandium Molybdate (Sc₂(MoO₄)₃) exhibits negative thermal expansion (NTE) properties over a wide temperature range.
- Electrochemical activation, involving ion insertion and extraction, can significantly modify the structural evolution and properties of related materials like Scandium Tungstate (Sc₂(WO₄)₃).
Purpose of the Study:
- To investigate the effects of electrochemical activation using lithium, sodium, and potassium on the phase evolution and thermal expansion behavior of Sc₂(MoO₄)₃.
- To compare the outcomes with those observed in structurally similar Sc₂(WO₄)₃.
Main Methods:
- Electrochemical discharge of Sc₂(MoO₄)₃ with Li, Na, and K counter electrodes to varying capacities.
- Subsequent thermal treatment of the electrochemically activated electrodes.
- Analysis of phase formation and structural changes using techniques not explicitly stated but implied by the results.
Main Results:
- Lithium-discharged Sc₂(MoO₄)₃ showed enhanced negative thermal expansion (CTE of -13.83(1) × 10⁻⁶/°C) and formed Li₂MoO₂ and Li₂MoO₄ phases.
- Further lithium discharge and thermal treatment led to the formation of Li₃ScMo₃O₁₂.
- Sodium and potassium discharge followed by thermal treatment resulted in the formation of new phases, including Na₀.₉Mo₂O₄, KMo₄O₆, and K₂MoO₄.
Conclusions:
- Electrochemical activation of Sc₂(MoO₄)₃ with alkali metals provides a pathway to access a rich diversity of new phases.
- These novel phases exhibit distinct thermal expansion characteristics, offering potential for advanced material applications.
- The study highlights the versatility of electrochemical methods in tailoring the properties of Sc₂(MoO₄)₃.
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