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An Unexpected Decrease in Vibrational Entropy of Multicomponent Rutile Oxides
Yaowen Wang1, Xinbo Li1, Jipeng Luo2
1State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012, P. R. China.
Journal of the American Chemical Society
|May 14, 2024
Summary
Vibrational entropy, often overlooked in high-entropy oxides (HEOs), significantly impacts their thermal stability. This study confirms its crucial role in lowering crystallization temperatures for multicomponent rutile HEOs.
Area of Science:
- Materials Science
- Thermodynamics
- Solid-State Chemistry
Background:
- High-entropy oxides (HEOs) possess unique properties due to their complex compositions.
- Configurational entropy is widely accepted as the primary driver of HEO thermal stability.
- The contribution of vibrational entropy to HEO thermodynamics remains largely unexplored.
Purpose of the Study:
- To systematically investigate the role of vibrational entropy in multicomponent rutile oxides.
- To determine how component disorder affects vibrational entropy in these materials.
- To elucidate the influence of excess vibrational entropy on the crystallization temperature of HEOs.
Main Methods:
- Precise heat capacity measurements were conducted on various multicomponent rutile oxides.
- Analysis included examining configuration disorder, size mismatch, phase transitions, and polyhedral distortions.
- Vibrational entropy was calculated and correlated with material characteristics.
Main Results:
- Vibrational entropy decreases with increasing component disorder, deviating from equilibrium predictions.
- All studied multicomponent rutile oxides exhibit positive excess vibrational entropy at 298.15 K.
- Excess vibrational entropy was identified as a key factor in reducing the crystallization temperature.
Conclusions:
- This research provides the first experimental evidence for the significant role of lattice vibrations in the thermodynamic landscape of rutile HEOs.
- Vibrational entropy is a critical factor influencing the thermal behavior and processing of HEOs.
- Vibrational entropy can be utilized as a novel descriptor for designing new multicomponent oxide materials.
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