Thermophysical properties of 1D materials: transient characterization down to atomic level

Figure  1.  (a, b) Schematic of the TET technique and TPET technique. (c) Graphene fiber TET signal with time as an example. Reproduced with permission from Ref. [54]. Copyright 2022. Elsevier. The inset is the suspended sample of 1.959 mm length. (d) Representation of the TET signal fitting: taking the natural of voltage subtracted by the steady state voltage. Reproduced with permission from Ref. [54]. Copyright 2022. Elsevier. The difference among the fittings using three different initial data treatments.

Figure  2.  (a) SEM images of single polyacrylonitrile (PAN) wires. Reproduced with permission from Ref. [60]. Copyright 2007. Springer Nature. (b) SEM images of carbon nanocoils (CNCs). Reprinted with permission from Ref. [57]. Copyright 2016. American Chemical Society. (c) SEM images of 3C crystalline silicon carbide (SiC) microwires. Reproduced with permission from Ref. [56]. Copyright 2018. Elsevier. (d) SEM images of carbon nanotube (CNT) bundles. Reproduced with permission from Ref. [61]. Copyright 2018. Elsevier.

Figure  3.  (a–c) The PLTR technique in the physical principle, schematics of the temperature response at the back side of the sample, and typical experimental data and fitting curve for in-plane heat conduction, respectively. Reproduced with permission from Ref. [65]. Copyright 2008. World Scientific Publishing. (d) Typical experimental data and fitting for cross-plane heat conduction. Reproduced with permission from Ref. [63]. Copyright 2017. Elsevier.

Figure  4.  Mathematical relation behind the physical models of different types of heat sources.

Figure  5.  (a) The cross-sectional schematic of a substrate with different nanofilm layers deposited. (b) Variation of the effective thermal diffusivity of an Ir-coated glass fiber against the inverse of the electrical resistance for 6.4 nm Ir layers coated on the glass fiber. (c) Linear fitting of ${\alpha _\text{eff}} \sim {L^2}$ for 1.33-layered graphene on PMMA. (d) Graphene temperature evolution with time and the temperature difference between PMMA and graphene in the middle point of the length direction. (b) Reprinted with permission from Ref. [75]. Copyright 2013. John Wiley and Sons, Inc. (c, d) Reproduced with permission from Ref. [59]. Copyright 2016. The Royal Society of Chemistry.

Figure  6.  Physical principle of the FET-Raman technique. (a) Temperature rise of the suspended sample under CW laser heating. (b) Amplitude-modulated laser heating.

Figure  7.  (a) 2D contour plot of the Raman shift for the G peak against laser power at 257 K for SWCNT bundles. Left side: for the CW case, the slope of linear fitting, as indicated with a solid black line, is ${\psi _\text{CW}} = (- 0.161 \pm 0.007)\,\,{\text{c}}{{\text{m}}^{ - 1}}\cdot{\text{m}}{{\text{W}}^{{ - 1}}}$. Right side: for the FR case, the slope of linear fitting, as indicated with a solid black line, is ${\psi _\text{FR}} = (- 0.118 \pm 0.006)\,\,{\text{c}}{{\text{m}}^{ - 1}}\cdot{\text{m}}{{\text{W}}^{{ - 1}}}$. (b) Theoretical values of the temperature rise ratio at 1 MHz from numerical modeling against the thermal diffusivity. Using the normalized RSC ($\varTheta$) from the experiment, the thermal diffusivity of SWCNTs can be interpolated, as indicated by the blue dashed line.