A Detailed Theoretical Study of the Thermal Conductivity of Bi2(Te0.85Se0.15)3 Single Crystals

2012 ◽  
Vol 1404 ◽  
Author(s):  
Ö. Ceyda Yelgel ◽  
Gyaneshwar P. Srivastava
Keyword(s):  
Thermal Conductivity ◽  
Single Crystals ◽  
Theoretical Investigation ◽  
Theoretical Study ◽  
Single Mode ◽  
Debye Model ◽  
Electron Hole ◽  
Electron Hole Pair ◽  
N Doping ◽  
Different Levels

ABSTRACTWe present a theoretical investigation of the thermal conductivity for n-type doped Bi2(Te0.85Se0.15)3 single crystals by using the Debye model within the single-mode relaxationtime approximation. A detailed account of alloy, electron-phonon, phonon-phonon and electron-hole pair (bipolar) interactions are included. Different levels (0.1 and 0.05 wt.%) of n-doping from CuBr and SbI3 dopants were considered. The calculated conductivity, by combining lattice (κ ph) and electronic bipolar (κ bp) contributions, successfully explains the experimental results obtained by Hyun et al. [J. Mat. Sci. 33 5595 (1998)]. The κ ph contribution was calculated using Srivastava’s scheme and the κ bp contribution was obtained by employing Price’s theory.

scholarly journals Photoelectrochemical and theoretical investigation of the photocatalytic activity of TiO2 : N

RSC Advances ◽  
2016 ◽  
Vol 6 (92) ◽  
pp. 89687-89698 ◽  
Author(s):  
Gabriela Byzynski Soares ◽  
Renan Augusto Pontes Ribeiro ◽  
Sergio Ricardo de Lazaro ◽  
Caue Ribeiro
Keyword(s):  
Photocatalytic Activity ◽  
Band Gap ◽  
Effective Mass ◽  
Theoretical Investigation ◽  
Hole Pair ◽  
Electron Hole ◽  
Electron Hole Pair ◽  
N Doping ◽  
Hole Recombination

In N-doping on TiO2 nanomaterial occurs a big decrease of band-gap (1 eV); however, its photocatalysis is low. We clarify such fact from effective mass, i.e., the electron–hole recombination is more than creation of electron–hole pair.

Misalignment Consideration in Laser Diode to Circular Core Single-Mode Dispersion-Shifted/Dispersion-Flattened Fiber Excitation via Hemispherical Microlens on the Tip of the Fiber

2016 ◽  
Vol 37 (2) ◽  
Author(s):  
Kiranmay Kamila ◽  
Tapas Ranjan Middya ◽  
Sankar Gangopadhyay
Keyword(s):  
Theoretical Investigation ◽  
Laser Diode ◽  
Theoretical Study ◽  
Single Mode ◽  
Simple Manner ◽  
Excitation Efficiency ◽  
Numerical Integrations ◽  
Mode Dispersion ◽  
Analytical Expressions ◽  
Model Technique

AbstractWe report the theoretical study of excitation efficiency in the presence of possible transverse and angular misalignments in the case of excitation of single-mode circular core dispersion-shifted and dispersion-flattened fiber by laser diode via hemispherical microlens on the tip of the fiber. The present study takes into consideration limited aperture allowed by the hemispherical microlens. Employing ABCD matrix technique involving refraction of paraxial rays by a hemispherical microlens on the fiber tip, we formulate analytical expressions for the coupling efficiencies in the presence of the said misalignments. The estimations of the concerned efficiencies as well as associated losses by using our formulations will require little computations. But the results found are sufficiently accurate and the execution of our formalism is simple. Thus the prescribed analytical expressions are useful and new in the sense that prediction of coupling optics can be made accurately but in a simple manner without requiring lengthy numerical integrations concerned with conventional phase model technique. Moreover, the present study, as per our knowledge till date, being the first theoretical investigation of excitation efficiency for the said type of coupling device, will benefit the experimentalists, designers and packagers who are working in the field of optimum launch optics involving such coupler.

Detailed Theoretical Investigation and Comparison of the Thermal Conductivities of n- and p-type Bi2Te3 Based Alloys

2013 ◽  
Vol 1543 ◽  
Author(s):  
Ö. Ceyda Yelgel ◽  
Gyaneshwar P. Srivastava
Keyword(s):  
Thermal Conductivity ◽  
Theoretical Investigation ◽  
Total Thermal Conductivity ◽  
Type Alloy ◽  
Electron Hole ◽  
Temperature Range ◽  
Image Position ◽  
P Type ◽  
Type 3 ◽  
Thermal Conductivities

ABSTRACTIn this work we present a detailed theoretical investigation of the thermal conductivities of n-type 0.1 wt.% CuBr doped 85% Bi2Te3 - 15% Bi2Se3 and p-type 3 wt% Te doped 20% Bi2Te3 - %80 Sb2Te3 single crystals. The thermal conductivity contributions arising from carriers, electron-hole pairs and phonons are computed rigorously in the temperature range $300\,{\rm{K}}\, \le \,T\, \le \,500\,{\rm{K}}$. In agreement with available experimental measurements we theoretically find that the lowest total thermal conductivity is 3.15 W K−1 m−1 at 380 K for the n-type alloy and 1.145 W K−1 m−1 at 400 K for the p-type alloy. Stronger mass-defect scattering is found to be responsible for the lower thermal conductivity of the p-type alloy throughout the temperature range of the study.

Ti3C2-MXene/Bismuth Ferrite Nanohybrids for Efficient Degradation of Organic Dye and Colorless Pollutant

2019 ◽  
Author(s):  
Ayesha Tariq ◽  
M. Abdullah Iqbal ◽  
S. Irfan Ali ◽  
Muhammad Z. Iqbal ◽  
Deji Akinwande ◽  
...  
Keyword(s):  
Surface Area ◽  
Low Cost ◽  
Bismuth Ferrite ◽  
Organic Dye ◽  
Two Dimensional ◽  
Electron Hole ◽  
Photocatalytic Application ◽  
Electron Hole Pair ◽  
Pair Generation ◽  
Photocatalytic Applications

<p>Nanohybrids, made up of Bismuth ferrites/Carbon allotropes, are extensively used in photocatalytic applications nowadays. Our work proposes a nanohybrid system composed of Bismuth ferrite nanoparticles with two-dimensional (2D) MXene sheets namely, the BiFeO<sub>3</sub> (BFO)/Ti<sub>3</sub>C<sub>2</sub> (MXene) nanohybrid for enhanced photocatalytic activity. We have fabricated the BFO/MXene nanohybrid using simple and low cost double solvent solvothermal method. The SEM and TEM images show that the BFO nanoparticles were attached onto the MXene surface and in the inter-layers of two-dimensional (2D) MXene sheets. The photocatalytic application is tested for the visible light irradiation which showed the highest efficiency among all pure-BFO based photocatalysts, i.e. 100% degradation in 42 min for organic dye (Congo Red) and colorless aqueous pollutant (acetophenone) in 150 min, respectively. The present BFO-based hybrid system exhibited the large surface area of 147 m<sup>2</sup>g<sup>-1</sup>measured via Brunauer-Emmett-Teller (BET) sorption-desorption technique, and is found to be largest among BFO and its derivatives. Also, the photoluminescence (PL) spectra indicate large electron-hole pair generation. Fast and efficient degradation of organic molecules is supported by both factors; larger surface area and lower electron-hole recombination rate. The BFO/MXene nanohybrid presented here is a highly efficient photocatalyst compared to other nanostructures based on pure BiFeO<sub>3</sub> which makes it a promising candidate for many future applications.</p>

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