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A 2019 study showed that electron irradiation combined with high-temperature annealing can shrink individual few-walled carbon nanotubes (CNTs) evenly while retaining a near-perfect lattice in the reported images. In one example, a double-walled tube’s outer diameter fell from 4.32 nm to 2.36 nm in 10 minutes. This was a controlled experiment inside a transmission electron microscope (TEM), not a demonstration of mass production.
How the shrinking process worked
Yong Cheng, Pei Li, Qiaobao Zhang, and corresponding author Ming-Sheng Wang at Xiamen University reported the method in 2019. They combined a 200 kV electron beam with simultaneous heating inside a TEM. The main experiments used double-walled CNTs synthesized by arc discharge, alongside a small number of tubes with one, three, or four walls. The study describes control of individual few-walled tubes, not a production line or a batch with standardized dimensions. Read the study in Nanoscale.
For the experiment, nanotubes rested on a thin silicon nitride film mounted on a MEMS-based heating chip. An FEI Talos F200s TEM and FEI-NanoEx heating holder provided the imaging and heating setup; the holder could reach temperatures up to 1200 °C. The researchers varied irradiation dose and annealing temperature, which they report strongly affected the shrinking rate.
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A measured example
Under a 20 A cm−2 beam dose at 1200 °C, a representative double-walled CNT’s outer diameter decreased from 4.32 nm to 2.36 nm after 10 minutes—approximately 45%. A separate imaged example reached an outer diameter of about 1.04 nm. These are reported outcomes for particular tubes and conditions, not guaranteed results for other samples.
#1 Best Overall
- 【Construction Style】: Built as a ball and model, it uses distinct black spheres for particles and white rods for relationships, creating a clear, easy to distinguish representation of the nanotube's interconnected framework.
- 【Visual Design】: This 3D carbon nanotube model forms a rounded cylindrical shape with an open lattice structure, offering views of internal connecting from multiple angles for demonstrations and study.
- 【Application Purpose】: Developed as a manual on teaching model, it supports classroom instruction, research facility reference, demonstrations, and individual study by making abstract nanoscale science tangible and viewable.
- 【Product Identity】: This carbon nanotube high density structure model is a three dimensional teaching tool built from glossy black spherical particle representations connected by white cylindrical linking rods, designed and materials science learning.
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What “uniform” means in this study
Here, “uniform” refers to the even contraction observed along an individual nanotube. The authors report regular kinks moving along the tube as it shrank and no visible lattice disorder in representative images. It does not mean that the researchers produced a large batch of tubes with the same diameter.
The authors propose that moving kinks mediate organized carbon removal through the climb motion of 5|7 dislocation cores, rather than dislocation glide. That is their explanation for the observed behavior, not a universal mechanism established for all carbon nanotubes or shrinking conditions.
How far can the diameter be reduced?
The paper gives an approximate lower-diameter relation for tubes with n shells, where n ≥ 2:
Dmin (nm) = 0.34 × (2n − 1)
The authors report shrinking ultrathin one- to four-walled tubes toward their respective diameter limits. For a double-walled tube, they describe an inner-shell diameter of about 3.2 Å at the theoretical stability limit; tubes broke apart when reduced below that point. This describes the reported experimental and theoretical limit, not a general specification for every CNT.
Rank #2
- 【Visual Design】: This 3D carbon nanotube model forms a rounded cylindrical shape with an open lattice structure, offering views of internal connecting from multiple angles for demonstrations and study.
- 【Application Purpose】: Developed as a manual on teaching model, it supports classroom instruction, research facility reference, demonstrations, and individual study by making abstract nanoscale science tangible and viewable.
- 【Product Identity】: This carbon nanotube high density structure model is a three dimensional teaching tool built from glossy black spherical particle representations connected by white cylindrical linking rods, designed and materials science learning.
- 【Construction Style】: Built as a ball and model, it uses distinct black spheres for particles and white rods for relationships, creating a clear, easy to distinguish representation of the nanotube's interconnected framework.
- 【Educational Function】: As a dedicated high density model, it visually demonstrates the open lattice arrangement of carbon particles, helping learners understand connecting patterns and the unique geometry of carbon nanotube structures.
How this differs from earlier shrinking approaches
The 2019 paper contrasts the method with earlier techniques based on tensile loading or Joule heating, which it says could manipulate one nanotube at a time and often yielded nonuniform shapes. The heating-chip experiment placed multiple tubes on a membrane, but that does not establish high-throughput processing: the work remained an in-situ TEM study of nanotubes under specialized laboratory conditions.
A separate 2008 in-situ TEM study examined nanotube growth and shrinkage during catalyst-free inner growth and cap evolution. It is not the same top-down diameter-control method described in the 2019 paper.
Why diameter control could matter—and what remains unproven
CNT diameter and chirality matter to potential uses such as transistors and photoelectronic devices. Shrinking an existing tube after growth could offer a way to tune its diameter rather than relying only on bottom-up synthesis to obtain a desired size.
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Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →The reported method demonstrates laboratory manipulation of diameter. It does not show arbitrary chirality selection, a finished transistor or photoelectronic device made from a shrunken tube, or a commercial manufacturing process. The authors’ abstract characterizes the approach as a top-down method for reliable control of the diameter of individual few-walled CNTs; that is the study authors’ claim about their experiment.
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