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Negative linear compressibility from helix in zinc carbodiimide
Chengxi Li1, Qiulin Chen1, Guohao Zhang1
1Laboratory of Quantum Functional Materials Design and Application, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou 221116, China. zengqx@jsnu.edu.cn.
Dalton Transactions (Cambridge, England : 2003)
|March 19, 2025
Summary
Zinc carbodiimide shows negative linear compressibility, expanding along one axis while compressed in others under pressure. This unique behavior arises from helical chain elongation in its crystal structure.
Area of Science:
- Materials Science
- Solid-State Physics
- Crystallography
Background:
- Negative linear compressibility (NLC) is a rare phenomenon where a material expands in one direction under compression.
- Understanding NLC is crucial for designing novel materials with unique mechanical properties.
Purpose of the Study:
- To investigate the mechanism of negative linear compressibility in zinc carbodiimide (Zn(CN2)).
- To explore the pressure-induced structural changes in Zn(CN2) using computational methods.
Main Methods:
- Density functional theory (DFT) calculations were employed to simulate the behavior of Zn(CN2) under hydrostatic pressure.
- Analysis of atomic positions, bond lengths, and lattice parameters under varying pressure conditions.
Main Results:
- Zinc carbodiimide (Zn(CN2)) exhibits significant negative linear compressibility along the c-axis.
- Under high hydrostatic pressure, the a- and b-axes of Zn(CN2) shrink.
- The infinite -Zn-N-C-N- helical chains elongate along the c-axis due to the strengthening of inter-chain Zn-N bonds, causing expansion.
Conclusions:
- The study elucidates the microscopic mechanism behind NLC in Zn(CN2).
- The unique helical chain structure and inter-chain bonding are key to its anisotropic compression behavior.
- Zn(CN2) serves as a model system for understanding and potentially engineering NLC materials.
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