Enhanced Thermal Stability and Broad Temperature Range in High-Entropy (La_0.2Ce_0.2Nd_0.2Sm_0.2Eu_0.2)NbO₄ Ceramics

Area of Science:

• Materials Science
• Solid State Chemistry
• Ceramic Engineering

Background:

• High-temperature applications require advanced thermistor materials with superior thermal stability and electrical performance.
• Current limitations in achieving high thermal stability and precision over wide temperature ranges hinder high-temperature applications.

Purpose of the Study:

• To design and investigate novel high-temperature thermistor ceramics using a high-entropy strategy.
• To address the bottleneck of limited thermal stability and precision in existing thermistor materials for high-temperature use.

Main Methods:

• Synthesis of high-entropy ceramics with the composition (La_0.2Ce_0.2Nd_0.2Sm_0.2Eu_0.2)NbO₄.
• Characterization of material properties, including lattice distortion, grain boundaries, dislocation density, charge carrier transport, and grain boundary resistance.
• Evaluation of thermal stability and precision over a wide temperature range (room temperature to 1523 K).

Main Results:

• The high-entropy composition induced significant lattice distortion, grain boundaries, and dislocation density.
• These microstructural features enhanced charge carrier transport and reduced grain boundary resistance.
• The developed thermistor ceramics demonstrated high precision and thermal stability from room temperature to 1523 K, with a low aging value of 0.42% after 1000 h at 1173 K.

Conclusions:

• The high-entropy strategy is an effective approach for developing advanced high-temperature thermistor ceramics.
• This work represents a breakthrough in enhancing the performance and broadening the operational temperature range of thermistor materials.
• The novel (La_0.2Ce_0.2Nd_0.2Sm_0.2Eu_0.2)NbO₄ ceramics show significant promise for next-generation high-temperature applications.