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3 Crystals
Published in D.M. Rowe, CRC Handbook of Thermoelectrics, 2018
At present solid solutions of the compounds bismuth telluride (BijTej), antimony telluride (SbiTej), and bismuth selerride (Bi2Se3) have the highest thermoelectric figures-of-merit in the temperature range around room temperature.2 The most suitable materials for the n-leg and the p-leg of thermocouples are the suitably doped mixed crystals n-Bi2(Te|.ySey)3 (y = 0.1) and p-(Bi|.xSbx)2Te3 (x = 0.75) and in the following sections the connection between the valence band structure and the thermoelectric figure-of-merit of (Bii.xSbx)2Te3 will be considered in detail.
Temporal and amplitude modulation at C-band region using Bi2Te3-based optical modulator
Published in Journal of Modern Optics, 2020
Harith Ahmad, Norazriena Yusoff, Hwee San Lim, Mohd. Zubir Mat Jafri, Mohd. Zamani Zulkifli, Zian Cheak Tiu
Figure 3(a) shows the nonlinear optical absorbance of the few-layers thick Bi2Te3 flakes investigated obtained using the balanced twin-detector method. For this measurement, a Menlo Systems ELMO femtosecond erbium-doped fibre laser (EDFL) is used as a pulsed 1564 nm source with the repetition rate of 100 MHz and a pulse width of 2.88 ps. The obtained measurements are fitted into the formula as shown in Equation (1): where α(I), αs, αns, I and Isat are the intensity-dependent absorption coefficient, saturable loss or modulation depth, non-saturable loss, pump light intensity and saturation intensity respectively. From the fitted curve, a modulation depth of 7.7% and saturation intensity of 1.47 kW/cm2 is computed. These values are comparable to those reported in other literature for other TI materials such as bismuth selenide (Bi2Se3) [29] and antimony telluride (Sb2Te3) [30,31]. The linear optical transmittance spectrum of the few-layers thick Bi2Te3 flakes is given in Figure 3(b) and is obtained using a white light source and an optical spectrum analyser (OSA). From the measured spectrum of 1400–1600 nm, it can be seen that the Bi2Te3 sample exhibits featureless linear absorbance with a transmission of about 70.58% at the region centred at 1561 nm.
An Investigation into the Thermal Boundary Resistance Associated with the Twin Boundary in Bismuth Telluride
Published in Nanoscale and Microscale Thermophysical Engineering, 2019
The twin boundaries are another potential scatters of phonons but not electrons due to its unique symmetry. Zhong et al. [6] fabricated highly twinned copper nanowires from an aqueous CuSO4 solution through direct electrodeposition; these wires had a high mechanical strength and no significantly deteriorated electric resistivity. Chang et al. [7] successfully fabricated a variety of highly oriented and twinned bismuth antimony telluride (BixSb2−xTe3) nanocrystals by a large-area pulsed-laser deposition technique. The significant presence of the nonbasal- and basal-plane twins across the hexagonal BiSbTe nanocrystals was observed and an enhanced power factor was measured. Medlin et al. [8, 9] also found that twin boundary structures in Bi2Te3 improve electron transport behavior. Besides, the interfacial energy differs when the twin boundary occurs at different atomic layers along the c-axis; the Te1-twin boundary is the most commonly observed one in the laboratories. While there are many studies which investigated the electric properties of twinned crystals, there are few literatures exploring the thermal conductivity. Mitchell and Anderson [10] investigated effects of various scattering mechanisms on the thermal conductivities of twinned and untwined indium-thallium alloys and found additional scattering at grain boundaries in twinned polycrystalline samples. Besides, they also proposed a modified acoustic mismatch model that could capture well the phonon scattering by the twin boundaries.
Pure antimony film as saturable absorber for Q-switched erbium-doped fiber laser
Published in Journal of Modern Optics, 2018
M. F. A. Rahman, M. Z. Zhalilah, A. A. Latiff, A. H. A. Rosol, M. Q. Lokman, A. R. Bushroa, K. Dimyati, S. W. Harun
To date, many other materials have been explored and proven to be able to generate a fiber pulse laser. These include titanium dioxide (TiO2) (17), holmium oxide (H2O3) (18) film SA, etc. Demonstrations of these materials will offer a variety of selections to the end users in deciding the best SA in term of cost, stability, set-up and fabrication for their laser operation. Previously, reports revealed that Antimony Telluride (Sb2Te3) SA, through mechanical exfoliation process, is able to produce stable pulse laser in Erbium-doped fiber laser (EDFL) cavity (19–22).