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 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.

scholarly journals Thermal conductivity of GaAs nanowires studied by micro-Raman spectroscopy combined with laser heating

2010 ◽  
Vol 97 (26) ◽  
pp. 263107 ◽  
Author(s):  
Martin Soini ◽  
Ilaria Zardo ◽  
Emanuele Uccelli ◽  
Stefan Funk ◽  
Gregor Koblmüller ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Laser Heating ◽  
Micro Raman Spectroscopy ◽  
Gaas Nanowires

Raman Spectra of Human Dental Calculus

1993 ◽  
Vol 72 (12) ◽  
pp. 1609-1613 ◽  
Author(s):  
H. Tsuda ◽  
J. Arends
Keyword(s):  
Raman Spectroscopy ◽  
Raman Spectra ◽  
Octacalcium Phosphate ◽  
Spot Size ◽  
Spectral Features ◽  
Dental Calculus ◽  
Micro Raman Spectroscopy ◽  
Vibrational Bands ◽  
First Time ◽  
Mineral Constituents

Raman spectra of human dental calculus have been observed for the first time by use of micro-Raman spectroscopy. The spectral features of calculus were influenced easily by heating caused by laser irradiation. Therefore, the measurements were carried out at relatively low power (5 mW, 1-μm spot size). The spectra could be characterized as phosphate vibrational bands due to the v1, v2, v 3, and v4 modes. The overall spectral features did not resemble those of pure minerals such as brushite, octacalcium phosphate, and hydroxyapatite. There were spectral differences among mixed calculus particles obtained from 18 adults, probably due to variations in local mineral composition and differences among patients. However, the averaged spectral features did not vary significantly with formation period from 1 to 6 months. Freshly removed and stored (5-11 months) calculus also gave comparable Raman spectra. Measurements on a fractured sample indicated that Raman spectra at saliva and dentin interfaces are nearly identical, and major mineral constituents may not vary significantly along the growth axis of calculus.

Measurement of In-Plane Thermal Conductivity of Ultrathin Films Using Micro-Raman Spectroscopy

2014 ◽  
Vol 18 (2) ◽  
pp. 183-193 ◽  
Author(s):  
Zhe Luo ◽  
Han Liu ◽  
Bryan T. Spann ◽  
Yanhui Feng ◽  
Peide Ye ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Ultrathin Films ◽  
Micro Raman Spectroscopy

Performance Analysis of Micro-Raman Spectroscopy Models for Thermal Conductivity Calculation

2021 ◽  
Author(s):  
Taher Meydando ◽  
Nazli Donmezer
Keyword(s):  
Thin Films ◽  
Thermal Conductivity ◽  
Raman Spectroscopy ◽  
Phonon Scattering ◽  
Raman Laser ◽  
Current Approach ◽  
Slab Model ◽  
Boltzmann Transport ◽  
Micro Raman Spectroscopy ◽  
Thermal Conductivities

Abstract Micro-Raman spectroscopy has been preferred recently to measure the thermal conductivity of thin-films due to its nondestructive and non-contact nature. However, the thermal size effects originating from both localized heat generation from Raman laser and phonon scattering at boundaries may cause erroneous estimation of the thermal conductivities with the current approach. In this study, the gray phonon Boltzmann transport equation (BTE) is solved to improve the results of micro-Raman thermal conductivity measurements. Due to the frequency independence of single phonon mode in the gray BTE model, our method stays ahead of most theoretical methods in calculation time while giving adequate agreement with the literature data. The improved thermal conductivities are evaluated at various laser powers and focal lengths. Subsequently, the values of thermal conductivities are compared with a simple slab model in which the deduction of thermal conductivity in sub-micron thicknesses is calculated using reduced heat flux through the slab resulting from phonon directional energy densities. The results show that subsequent errors are present in measuring the thermal conductivity of relatively thick, thin films with this technique which are noticed by comparing with the simple slab model. Finally, a virtual micro-Raman thermography experiment is developed, and its validity is verified by the same slab model.

Temperature-dependent Raman spectra and thermal conductivity of multi-walled MoS2 nanotubes

2017 ◽  
Vol 111 (12) ◽  
pp. 123102 ◽  
Author(s):  
Dongqing Yu ◽  
Siqi Li ◽  
Weihong Qi ◽  
Mingpu Wang
Keyword(s):  
Thermal Conductivity ◽  
Raman Spectra ◽  
Temperature Dependent ◽  
Mos2 Nanotubes

scholarly journals Raman Spectroscopy as a Potential Tool for Detection of Brucella spp. in Milk

2012 ◽  
Vol 78 (16) ◽  
pp. 5575-5583 ◽  
Author(s):  
Susann Meisel ◽  
Stephan Stöckel ◽  
Mandy Elschner ◽  
Falk Melzer ◽  
Petra Rösch ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Single Cell ◽  
Raman Spectra ◽  
Detection System ◽  
Support Vector ◽  
Promising Alternative ◽  
Content Type ◽  
Micro Raman Spectroscopy ◽  
Genotypic Characteristics ◽  
Potential Tool

ABSTRACTDetection ofBrucella, causing brucellosis, is very challenging, since the applied techniques are mostly time-demanding and not standardized. While the common detection system relies on the cultivation of the bacteria, further classical typing up to the biotype level is mostly based on phenotypic or genotypic characteristics. The results of genotyping do not always fit the existing taxonomy, and misidentifications between genetically closely related genera cannot be avoided. This situation gets even worse, when detection from complex matrices, such as milk, is necessary. For these reasons, the availability of a method that allows early and reliable identification of possibleBrucellaisolates for both clinical and epidemiological reasons would be extremely useful. We evaluated micro-Raman spectroscopy in combination with chemometric analysis to identifyBrucellafrom agar plates and directly from milk: prior to these studies, the samples were inactivated via formaldehyde treatment to ensure a higher working safety. The single-cell Raman spectra of differentBrucella,Escherichia,Ochrobactrum,Pseudomonas, andYersiniaspp. were measured to create two independent databases for detection in media and milk. Identification accuracies of 92% forBrucellafrom medium and 94% forBrucellafrom milk were obtained while analyzing the single-cell Raman spectra via support vector machine. Even the identification of the other genera yielded sufficient results, with accuracies of >90%. In summary, micro-Raman spectroscopy is a promising alternative for detectingBrucella. The measurements we performed at the single-cell level thus allow fast identification within a few hours without a demanding process for sample preparation.

scholarly journals Meridianiite detected in ice

2009 ◽  
Vol 55 (189) ◽  
pp. 117-122 ◽  
Author(s):  
F. Elif Genceli ◽  
Shinichirou Horikawa ◽  
Yoshinori Iizuka ◽  
Toshimitsu Sakurai ◽  
Takeo Hondoh ◽  
...  
Keyword(s):  
Raman Spectroscopy ◽  
Low Temperature ◽  
Sea Ice ◽  
Magnesium Sulfate ◽  
Raman Spectra ◽  
Sulfate Salt ◽  
Micro Raman Spectroscopy ◽  
Naturally Occurring ◽  
Formation History ◽  
History Of

AbstractInclusions affect the behavior of ice, and their characteristics help us understand the formation history of the ice. Recently, a low-temperature magnesium sulfate salt was discovered. This paper describes this naturally occurring MgSO4·11H2O mineral, meridianiite, derived from salt inclusions in sea ice of Lake Saroma, Japan and in Antarctic continental core ice. Its occurrence is confirmed by using micro-Raman spectroscopy to compare Raman spectra of synthetic MgSO4·11H2O with those of the inclusions.

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