Researchers from Skoltech, in collaboration with the Harbin Institute of Technology and Jiangsu University (China), have published a study presenting the first empirical model to explain and predict the sensing behavior of hierarchical tri-phase carbon nanotube systems across a wide temperature range (from -170°С to 90°C). The study supported by a grant from the Russian Science Foundation has been published in the Carbon journal.
Single-walled carbon nanotubes (SWCNTs), a backbone of advanced multifunctional materials, can be produced in the form of powders, films, or fibers. In this study, the authors combined multiple forms to determine the practical limitations of smart materials which may affect their usage as sensors in extreme conditions.
“Carbon nanotube fibers (CNTFs) and SWCNT nanocomposites are very versatile materials. They are strong, highly conductive and self-sensing towards strain, chemical species, and temperature,” explains Nikita Gordeev, PhD student from the Skoltech Physics program and first author of the study. “However, this multi-aspect sensitivity poses a significant dilemma. If a material is sensitive to everything at once, it is difficult to determine what is causing the change. Delineating these signals is a challenge, but is necessary to understand what exactly the material is reacting to”.
The team has discovered that despite their different structures, the temperature-dependent electrical behavior of uni-, bi-, and tri-phase systems is governed by the same underlying competition between charge carriers hopping at cryogenic temperatures and metallic-like scattering at high temperatures.
Associate Professor Dmitry Krasnikov from the Skoltech Photonics Center highlighted the elegance of this finding: “This unifying law can be found across many branches of physics and natural sciences. It is truly beautiful when such a complex, multi‑phase system obeys such a universal principle.”
“Next-generation materials allow system streamlining by using one material to do the tasks currently handled by many different systems and materials. By targeting research towards material sensors which are to be integrated into the market in the future, we are making sure that we lead the race to their widescale adoption. For this, we need to know how these materials interact with each other, what their limitations are, and what we can do to improve them,” noted Assistant Professor Hassaan Ahmad Butt from the Skoltech Photonics Center.
“This study lays a foundation for hierarchical carbon materials which are on the horizon of being adopted by the industry,” commented Professor Albert Nasibulin, the director of the Skoltech Photonics Center and the head of the center’s Laboratory of Nanomaterials. “SWCNT-based materials are undeniably impressive. CNTFs provide extremely high conductance to weight ratios, and can be integrated into aerospace grade composites as sensors or wiring without any loss to the host material. Homogeneously dispersed SWCNT polymer nanocomposites provide a multifunctional base that the current composite generation simply can’t provide. Combining the two to make smart materials engineered from the ground up to provide strength, electrical and thermal performance and real-time monitoring is the next step. However, their complex temperature-dependent behavior was a hard nut to crack. With this work, we now understand how their sensing performance alters at the extreme temperatures that large systems, such as aircraft, experience, and how to delineate this from other stimuli.”
