Isotropic Zero Thermal Expansion in Yb(Al,Mn)₂: Achieving Continuous Shiftability over a Wide Temperature Range.

Area of Science:

• Materials Science
• Condensed Matter Physics

Background:

• Zero thermal expansion (ZTE) materials are crucial for advanced technologies but face challenges like anisotropy and limited operating temperatures.
• Existing ZTE materials often exhibit limitations such as ferromagnetism, high density, and narrow ZTE temperature windows.

Purpose of the Study:

• To achieve lightweight, nonferromagnetic, and isotropic ZTE materials with tunable temperature windows.
• To elucidate the underlying mechanisms responsible for the observed zero thermal expansion behavior and its shiftability.

Main Methods:

• Synthesis and characterization of Yb(Al,Mn)2 alloys.
• Utilizing advanced experimental techniques and first-principles calculations.
• Investigating valence fluctuations and local structural distortions.

Main Results:

• Achieved lightweight, nonferromagnetic, isotropic ZTE in Yb(Al,Mn)2 alloys.
• Demonstrated continuous shiftability of the ZTE temperature window from 140 K to 650 K.
• Identified valence fluctuations and Mn-3d/Yb-4f orbital hybridization as key mechanisms.

Conclusions:

• The study presents an unprecedented continuously shiftable ZTE temperature window in a mixed-valence system.
• Valence fluctuation modulation offers new strategies for designing advanced ZTE materials.
• These findings pave the way for next-generation devices demanding exceptional dimensional stability.