scholarly journals Study of Thermometry in Two-Dimensional Sb2Te3 from Temperature-Dependent Raman Spectroscopy

2021 ◽  
Vol 16 (1) ◽  
Author(s):  
Manavendra P. Singh ◽  
Manab Mandal ◽  
K. Sethupathi ◽  
M. S. Ramachandra Rao ◽  
Pramoda K. Nayak
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Temperature Coefficient ◽  
Heat Dissipation ◽  
Peak Position ◽  
Two Dimensional ◽  
Phonon Modes ◽  
Temperature Dependent ◽  
Excellent Candidate ◽  
High Figure

AbstractDiscovery of two-dimensional (2D) topological insulators (TIs) demonstrates tremendous potential in the field of thermoelectric since the last decade. Here, we have synthesized 2D TI, Sb2Te3 of various thicknesses in the range 65–400 nm using mechanical exfoliation and studied temperature coefficient in the range 100–300 K using micro-Raman spectroscopy. The temperature dependence of the peak position and line width of phonon modes have been analyzed to determine the temperature coefficient, which is found to be in the order of 10–2 cm−1/K, and it decreases with a decrease in Sb2Te3 thickness. Such low-temperature coefficient would favor to achieve a high figure of merit (ZT) and pave the way to use this material as an excellent candidate for thermoelectric materials. We have estimated the thermal conductivity of Sb2Te3 flake with the thickness of 115 nm supported on 300-nm SiO2/Si substrate which is found to be ~ 10 W/m–K. The slightly higher thermal conductivity value suggests that the supporting substrate significantly affects the heat dissipation of the Sb2Te3 flake.

Study of thermal conductivity in two-dimensional Bi2Te3 from micro-Raman spectroscopy

2021 ◽  
Vol 01 ◽  
Author(s):  
Manavendra P. Singh ◽  
Sumarlang Ryntathiang ◽  
Sivarama Krishnan ◽  
Pramoda K. Nayak
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Temperature Coefficient ◽  
Raman Spectra ◽  
Heat Dissipation ◽  
Surface States ◽  
Power Coefficient ◽  
Great Promise ◽  
Temperature Dependent ◽  
Micro Raman Spectroscopy

Background: Topological insulator (TI), Bi2Te3 is a new class of the quantum materials. Having ultralow dissipation surface states, TIs hold great promise toward different potential applications. Micro-Raman spectroscopy is a conventional and non-destructive technique, which has been widely used to characterize the structural and electronic properties of the thermoelectric materials. Objective: To study power dependent and temperature dependent Raman spectra of Bi2Te3 nano flakes on SiO2/Si substrate to estimate the temperature coefficient and thermal conductivity of these flakes for possible application of this material in thermoelectrics. Method: Bi2Te3 flakes of different thicknesses were mechanically exfoliated from high quality bulk Bi2Te3 crystal using scotch tape on 300 nm SiO2/ Si substrates. The power dependent and temperature dependent Raman spectra were acquired with the help of HORIBA LabRAM confocal micro-Raman system in a back scattering geometry. Result: . The observed power dependent and temperature dependent Raman spectra of Bi2Te3 nano flakes follow the same trend as discussed in various literatures. From temperature coefficient and power coefficient values, the in plane thermal conductivity has been estimated, which is found to be in the order of 10 2 W/m-K. The enhancement in the thermal conductivity suggests that the underlying substrate significantly affects the heat dissipation of the Bi2Te3 flake based on the coupling strength with Bi2Te3. Conclusion: This work provides a good platform to understand the role of substrate on the thermal conductivity of exfoliated Bi2Te3 nano flakes and this study can be extended to other substrates.

scholarly journals Temperature-Dependent Raman Scattering of Large Size Hexagonal Bi2Se3 Single-Crystal Nanoplates

2018 ◽  
Vol 8 (10) ◽  
pp. 1794 ◽  
Author(s):  
Fang Zhou ◽  
Yujing Zhao ◽  
Weichang Zhou ◽  
Dongsheng Tang
Keyword(s):  
Electron Microscope ◽  
Single Crystal ◽  
Temperature Coefficient ◽  
Thermoelectric Materials ◽  
Large Scale ◽  
X Ray Diffraction ◽  
Temperature Dependent ◽  
Large Size ◽  
Transmission Electron ◽  
High Figure

Bi 2 Se 3 has extensive application as thermoelectric materials. Here, large-scale Bi 2 Se 3 single-crystal hexagonal nanoplates with size 7.50–10.0 μ m were synthesized successfully by hydrothermal method. X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscope (TEM) were used to characterize the Bi 2 Se 3 nanoplates, which confirm the single-crystal quality and smooth surface morphology with large size. Micro-Raman spectra over a temperature range of 83–603 K were furthermore used to investigate the lattice dynamics of Bi 2 Se 3 nanoplates. Both 2A g 1 and 1E g 2 modes shift evidently with reduced temperature. The line shape demonstrates a significant broadening of full width at half maximum (FWHM) and red-shift of frequency with increased temperature. The temperature coefficient of A 1 g 1 , E g 2 , A 1 g 2 modes were determined to be −1.258 × 10 − 2 cm − 1 /K, −1.385 × 10 − 2 cm − 1 /K, −2.363 × 10 − 2 cm − 1 /K, respectively. Such low temperature coefficient may favor the obtaining of a high figure of merit (ZT) and indicate that Bi 2 Se 3 nanoplates were used as excellent candidates of thermoelectric materials.

scholarly journals Anomalous strain effect on the thermal conductivity of low-buckled two-dimensional silicene

2020 ◽  
Author(s):  
Bin Ding ◽  
Xiaoyan Li ◽  
Wuxing Zhou ◽  
Gang Zhang ◽  
Huajian Gao
Keyword(s):  
Thermal Conductivity ◽  
Strain Effect ◽  
Two Dimensional ◽  
Phonon Modes ◽  
Heat Management ◽  
Anomalous Effect ◽  
Long Wavelength ◽  
Two Dimensional Materials ◽  
Dynamics Simulations ◽  
Energy Conversion Devices

Abstract The thermal conductivity of two-dimensional materials, such as graphene, typically decreases when tensile strain is applied, which softens their phonon modes. Here, we report an anomalous strain effect on the thermal conductivity of monolayer silicene, a representative low-buckled two-dimensional (LB-2D) material. ReaxFF-based molecular dynamics simulations are performed to show that biaxially stretched monolayer silicene exhibits a remarkable increase in the thermal conductivity, by as much as 10 times the freestanding value, with increasing applied strain in the range of [0, 0.1], which is attributed to increased contributions from long-wavelength phonons. A further increase in strain in the range of [0.11, 0.18] results in a plateau of the thermal conductivity in an oscillatory manner, governed by a unique dynamic bonding behavior under extreme loading. This anomalous effect reveals new physical insights into the thermal properties of LB-2D materials and may provide some guidelines for designing heat management and energy conversion devices based on such materials.

scholarly journals Optical Contrast and Raman Spectroscopy Techniques Applied to Few-Layer 2D Hexagonal Boron Nitride

Nanomaterials ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 1047 ◽  
Author(s):  
Marie Krečmarová ◽  
Daniel Andres-Penares ◽  
Ladislav Fekete ◽  
Petr Ashcheulov ◽  
Alejandro Molina-Sánchez ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Boron Nitride ◽  
Phonon Mode ◽  
Hexagonal Boron Nitride ◽  
Linear Trend ◽  
Thickness Dependence ◽  
Two Dimensional ◽  
Phonon Modes ◽  
Optical Contrast ◽  
Si Substrates

The successful integration of few-layer thick hexagonal boron nitride (hBN) into devices based on two-dimensional materials requires fast and non-destructive techniques to quantify their thickness. Optical contrast methods and Raman spectroscopy have been widely used to estimate the thickness of two-dimensional semiconductors and semi-metals. However, they have so far not been applied to two-dimensional insulators. In this work, we demonstrate the ability of optical contrast techniques to estimate the thickness of few-layer hBN on SiO2/Si substrates, which was also measured by atomic force microscopy. Optical contrast of hBN on SiO2/Si substrates exhibits a linear trend with the number of hBN monolayers in the few-layer thickness range. We also used bandpass filters (500–650 nm) to improve the effectiveness of the optical contrast methods for thickness estimations. We also investigated the thickness dependence of the high frequency in-plane E2g phonon mode of atomically thin hBN on SiO2/Si substrates by micro-Raman spectroscopy, which exhibits a weak thickness-dependence attributable to the in-plane vibration character of this mode. Ab initio calculations of the Raman active phonon modes of atomically thin free-standing crystals support these results, even if the substrate can reduce the frequency shift of the E2g phonon mode by reducing the hBN thickness. Therefore, the optical contrast method arises as the most suitable and fast technique to estimate the thickness of hBN nanosheets.

scholarly journals Vibrational spectra of Pb2Bi2Te3, PbBi2Te4, and PbBi4Te7 topological insulators: temperature-dependent Raman and theoretical insights from DFT simulations

2019 ◽  
Vol 21 (27) ◽  
pp. 15030-15039 ◽  
Author(s):  
Priyanath Mal ◽  
G. Bera ◽  
G. R. Turpu ◽  
Sunil K. Srivastava ◽  
A. Gangan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Frequency Shift ◽  
Vibrational Spectra ◽  
Topological Insulators ◽  
Lead Telluride ◽  
Phonon Modes ◽  
Temperature Dependent ◽  
Dft Simulations

Insertion of lead and lead telluride in Bi2Te3 leads to a change in the thermal conductivity, frequency shift, and the broadening of phonon modes.

Anomalous temperature dependent thermal conductivity of two-dimensional silicon carbide

2019 ◽  
Vol 30 (44) ◽  
pp. 445707 ◽  
Author(s):  
A S M Jannatul Islam ◽  
Md Sherajul Islam ◽  
Naim Ferdous ◽  
Jeongwon Park ◽  
A G Bhuiyan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Silicon Carbide ◽  
Two Dimensional ◽  
Temperature Dependent ◽  
Anomalous Temperature ◽  
Temperature Dependent Thermal Conductivity

Anomalous Effect on the Phononic Thermal Conductivity of Silicene Nanoribbon by Hydrogenation

2015 ◽  
Vol 1105 ◽  
pp. 110-114 ◽  
Author(s):  
Emmanuel Dioresma Monterola ◽  
Naomi Tabudlong Paylaga ◽  
Giovanni Jariol Paylaga ◽  
Rolando Viño Bantaculo
Keyword(s):  
Thermal Conductivity ◽  
Molecular Dynamics ◽  
Silicon Nanowires ◽  
Large Scale ◽  
Massively Parallel ◽  
Two Dimensional ◽  
Phonon Modes ◽  
Anomalous Effect ◽  
Hydrogenated Silicon ◽  
Out Of Plane

Silicene is a two-dimensional (2D) allotrope of silicon known to have a lower thermal conductivity than graphene; thus, more suitable for thermoelectric applications. This paper investigates the effect of hydrogenation on the thermal conductivity of silicene nanoribbon (SiNR) using equilibrium molecular dynamics (EMD) simulations. The simulations were carried out in Large-scale Atomic/Molecular Massively Parallel Simulator (LAMMPS) using a modified Tersoff potential that considers both Si-Si and Si-H interactions. The thermal conductivity of fully hydrogenated silicene nanoribbon (H-SiNR), also known as silicane nanoribbon, was found to be higher than that of pristine SiNR in all the temperatures and dimensions considered here. This anomalous enhancement in the thermal conductivity is similar to that found in hydrogenated silicon nanowires (H-SiNWs). A mechanism for this anomalous effect has been proposed relating the hydrogenation of SiNR with the stiffening and increase of the acoustic out-of-plane flexural (ZA) phonon modes. Also, for both SiNR and H-SiNR, the thermal conductivities generally increase as the dimensions are increased while they generally decrease as the temperatures are increased, in agreement to other reports.

scholarly journals Non-Fourier Heat Conduction Analysis with Temperature-Dependent Thermal Conductivity

2011 ◽  
Vol 2011 ◽  
pp. 1-10 ◽  
Author(s):  
H. Rahideh ◽  
P. Malekzadeh ◽  
M. R. Golbahar Haghighi
Keyword(s):  
Thermal Conductivity ◽  
Finite Element ◽  
Degrees Of Freedom ◽  
Differential Quadrature Method ◽  
Two Dimensional ◽  
Temperature Dependent ◽  
Temporal Domain ◽  
Fourier Heat Conduction ◽  
The One ◽  
Temperature Dependent Thermal Conductivity

As a first endeavor, the one- and two-dimensional heat wave propagation in a medium subjected to different boundary conditions and with temperature-dependent thermal conductivity is studied. Both the spatial as well as the temporal domain is discretized using the differential quadrature method (DQM). This results in superior accuracy with fewer degrees of freedom than conventional finite element method (FEM). To verify this advantage through some comparison studies, a finite element solution ise also obtained. After demonstrating the convergence and accuracy of the method, the effects of different parameters on the temperature distribution of the medium are studied.

Temperature dependent thermal conductivity of IIa diamond by laser excited Raman spectroscopy

2021 ◽  
Vol 118 (19) ◽  
pp. 192104
Author(s):  
Zhijian Guo ◽  
Liang Wang ◽  
Kaiyue Wang ◽  
Chunhui Ren ◽  
Ruiang Guo ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Temperature Dependent ◽  
Temperature Dependent Thermal Conductivity
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