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Hybrid Power for Mobile Systems
Published in Yatish T. Shah, Hybrid Power, 2021
The radioisotope thermoelectric generators (RTGs) are a solid and highly reliable source of electrical energy to power space vehicles being capable of operating in vacuum and to resist at high vibrations. RTGs are used to power space vehicles for distant NASA space expeditions (e.g., several years or several decades) where sunlight is not enough to supply solar panels. The natural radioactive decay of plutonium-238 releases huge amounts of heat, suitable for utilization in RTGs to convert it into electricity. The heat source temperature in this case is about 1000oC [32]. At this high temperature, semiconductor materials used in RTG can be silicon germanium (Si Ge), lead tin telluride (PbSnTe), tellurides of antimony, germanium, and silver (TAGS) and lead telluride (PbTe).
Peculiarities of conductivity of PbSnTe(In) in the persistent photoconductivity regime.
Published in J Kono, J Léotin, Narrow Gap Semiconductors, 2006
A E Kozhanov, S N Chesnokov, L I Ryabova, D R Khokhlov
Lead telluride-based solid solutions grow with a high deviation from the stoichiometry and all native defects are electrically active, so high concentration of vacancies and interstitial atoms results in high free carrier concentration of about 1019cm−3. Free carrier density can be further controlled via doping of the initial PbTe and its solid solutions with elements of several groups of the Periodic Table (e.g. I, III, V, VII group elements). Doping of the lead tin telluride with certain impurities results in the strong and unusual effects (such as Fermi level pinning and persistent photoconductivity) which are not characteristic for the undoped material [2]. In particular, doping of the lead telluride-based alloys with In or Ga leads to the Fermi level pinning effect and to appearance of long-term relaxation phenomena at low temperatures. Position of the pinned Fermi level in case of Pb1-xSnxTe solid solutions could be effectively manipulated by changing the tin concentration x. At 0.22<x<0.28, the Fermi level can be pinned within the gap leading to appearance of a semiinsulating state at low temperatures. This is explained by assuming that the dopant serves as a multi-charge center (with In+, In2+ and In+ states) [3]. The neutral (with respect to the lattice) In2+ state is unstable and decays to a donor or an acceptor: 2In2+ → In+ + In3+. In this case the persistent photoconductivity is observed.
Lasers for Spectroscopy
Published in Leon J. Radziemski, Richard W. Solarz, Jeffrey A. Paisner, Laser Spectroscopy and Its Applications, 2017
The best modern semiconductor diode lasers take advantage of waveguiding effects to give lower laser threshold current and better beam quality and have a structure composed of several layers rather than a single simple pn junction. Figure 2.5 shows the more complex multilayered structure of a particularly popular design called a “double heterojunction” as executed in a mixed lead-tin telluride [Groves, 1974; Tomasetta, 1974]. The design principles of this and other laser structures are discussed in the reviews listed in the first paragraph of this section.
EUROCORR 2019: ‘New Times, New Materials, New Corrosion Challenges’ Part 4
Published in Corrosion Engineering, Science and Technology, 2020
‘Study of the degradation of different thermoelectric modules at Teide National Park’ was outlined by L. Catalán (Public University of Navarre, Spain). Supplying power to volcanic monitoring stations constitutes a challenge due to access and the acidic environments of volcanos. Using semiconducting modules, heat is transformed into electricity by the Seebeck effect. The degradation of Marlow TF12-8 (bismuth-telluride), European Thermodynamics GM200-127-14-16 (bismuth-telluride) and TECTEG TEG1-PB-12690 (lead–tin–telluride) were studied. In one experiment, modules were exposed adjacent to a fumarole for 8 months; in the other, an accelerated corrosion test in the lab, using gases of similar composition, were used. In both cases, the variation in the generation capacity of the thermoelectric modules for different load resistances and similar heating conditions showed significant degradation of the modules, mainly due to copper corrosion.