Synergistic Entropy Engineering with Oxygen Vacancy: Modulating Microstructure for Extraordinary Thermosensitive...

Area of Science:

• Materials Science
• Solid State Chemistry
• Sensor Technology

Background:

• High-temperature thermistors require both precision and stability, which are often compromised in conventional spinel or perovskite materials.
• Existing thermosensitive materials struggle with long-term performance in extreme environments due to sensitivity-stability trade-offs.

Purpose of the Study:

• To develop a novel entropy engineering strategy to balance sensitivity and stability in fergusonite-structured ReNbO4 materials for high-temperature applications.
• To investigate the role of oxygen vacancies in enhancing the electronic structure and microstructural stability of these materials.

Main Methods:

• Entropy engineering involving vacancies and allovalent substitution on the A-site of fergusonite-structured ReNbO4.
• Characterization of microstructural features, electronic structure, and thermosensitive properties.
• High-temperature performance testing over an extended temperature range (223-1423 K).

Main Results:

• Unusually high concentrations of oxygen vacancies were generated, improving electronic structure and structural stability.
• Entropy engineering introduced stable microstructural features like twinned domains and lattice distortions.
• The resulting high-entropy ceramics exhibited low aging drift and high accuracy from 223 K to 1423 K.
• A competitive temperature coefficient of resistivity of 0.223%/K was achieved at 1423 K.

Conclusions:

• The proposed entropy engineering strategy effectively balances sensitivity and stability in ReNbO4 for extreme environments.
• Oxygen vacancies play a crucial role in enhancing material performance for high-temperature thermosensitive sensors.
• This work establishes a new paradigm for designing advanced materials using vacancy-involved entropy engineering.