Rare Iron Form Found in Carbon Nanotubes | New Research

Breakthrough in Nanomaterial Design Could Revolutionize Quantum Technologies

A new study from Xi’an Jiaotong-Liverpool University (XJTLU) details a method for stabilizing unusual iron structures within carbon nanotubes, possibly unlocking advancements in magnetic materials, spintronics, and quantum computing.

Researchers, led by Dr. filippo boi of the Department of Chemistry, have successfully confined iron into a configuration that would normally be unstable under standard conditions.This unique configuration exhibits promising magnetic properties crucial for next-generation technologies.

Confining Iron at the Nanoscale

Carbon nanotubes, envisioned as rolled-up sheets of carbon atoms, serve as the ideal surroundings for this research. The team focused on creating tiny iron wires,measured in nanometres,and embedding them within the nanotubes. This was achieved through an advanced fabrication process called chemical vapour deposition, resulting in a film of nanotubes each filled wiht continuous iron-based nanowires.

The key to stabilizing these unusual iron phases-specifically face-centred cubic and hexagonal close-packed iron-lay in carefully controlling the cooling process. By employing a combination of slow and rapid cooling sequences,the researchers were able to maintain these non-equilibrium phases at room temperature.

Unveiling Unique Magnetic Behavior

The encapsulated iron nanowires demonstrate a rare combination of ferromagnetic and antiferromagnetic properties. In ferromagnetic materials, atomic magnetic moments align, creating a strong magnetic field. Conversely, antiferromagnetic materials exhibit opposing alignment. the simultaneous presence of both, linked by sharp interfaces, results in a phenomenon known as exchange-bias, a critical component in spintronics, magnetic data recording, and spin-valve technology.

“By combining precise synthesis control with nanoscale imaging and magnetic characterisation, we can directly observe the atomic-level transformations that determine a material’s behavior,” Dr. Boi explained.

Expanding the Possibilities

The research team believes this method isn’t limited to iron. They suggest it can be applied to other metallic nanowires, including nickel, cobalt, and their alloys, to stabilize high-pressure phases under normal conditions.This opens doors for further exploration in fields like biomagnetism,materials physics,nanomagnetism,and beyond. Potential applications include advanced quantum data storage devices and innovative nano-heater technologies for nanomedicine.

The team’s findings,published recently in the journal Carbon,represent a notable step forward in understanding and manipulating materials at the nanoscale.The research was conducted in collaboration with Dr. Qiuchen Dong, zihui Qiu, and Jianfang Wu from the School of Science.

Read the team’s research paper, “possible confinement of hcp ε-Fe martensite, atomic-shuffling, stacking-fault nucleation and large-coercivities in Fe-filled multiwall carbon nanotubes,” here.

A high-resolution transmission electron micrograph (HRTEM) visually confirms the encapsulation of the hexagonal close-packed ε-Fe martensite phase within a multiwall carbon nanotube (CNT). (Credit: Boi, et al, DOI: 10.1016/j.carbon.2025.120932)

This research underscores the potential of nanoscale confinement to unlock previously unattainable material properties, paving the way for a new era of technological innovation.