Room Temperature Zero Thermal Expansion in a Cubic Cobaltite

Area of Science:

• Materials Science
• Solid State Physics
• Magnetism

Background:

• Zero thermal expansion (ZTE) materials are critical for high-precision industries.
• Existing ZTE materials like Invar alloys rely on the magnetovolume effect (MVE), whose origin remains debated.
• Pure-form ZTE materials are exceptionally rare.

Purpose of the Study:

• To discover and characterize a novel pure-form material exhibiting room-temperature isotropic zero thermal expansion.
• To investigate the underlying mechanism of ZTE in the discovered material.
• To explore potential applications and tunability of the ZTE phenomenon.

Main Methods:

• Synthesis and characterization of A-site disordered La0.5Ba0.5CoO3- perovskite.
• Temperature-dependent structural and magnetic measurements.
• Analysis of thermal expansion behavior and its correlation with magnetic ordering.

Main Results:

• Discovery of room-temperature isotropic zero thermal expansion in La0.5Ba0.5CoO3-.
• Demonstration of tunable anomalous thermal expansion by adjusting oxygen content.
• Identification of ZTE originating from an isostructural transition between antiferromagnetic and ferromagnetic phases.

Conclusions:

• La0.5Ba0.5CoO3- is a promising pure-form ZTE material with tunable properties.
• The observed ZTE mechanism provides new insights into the magnetovolume effect in Invar alloys.
• This discovery opens avenues for advanced applications requiring dimensional stability.