http://www.mdpi.com/journal/materials/special_issues/thermoelectric-materials/ 2nd Thermopower Symposium - Novel Thermoelectric Materials and Applications, July 24th 2009 at Empa Dübendorf, Switzerland Dear Colleagues, The TEP-CH Symposium is coupled to the International Conference on Thermoelectrics ICT-ECT in Freiburg/Brsg on July 26-30 and the workshop on "Relationship between (nano)structures and thermoelectric properties" at CRISMAT Caen on July 22, 2009. The aim of the proceedings publications of the symposium is to give an updated overview on recent research results from universities, scientific institutes as well as from industry on this exiting interdisciplinary topic to promote the development of thermoelectric materials and devices. The topics include all aspects of thermoelectric energy conversion, such as: Theory and fundamentals of thermoelectricity Development of novel thermoelectric materials, including preparation techniques, innovative synthesis methods (Thin films, soft chemistry, etc.) Design of devices, including Micro Thermoelectric Converters Applications in cooling and electricity generation Characterisation and measurement techniques Thomas Lipper, Ph. D. Prof. Dr. Anke Weidenkaff Guest Editors {snippet name="submission_info"}  http://www.mdpi.com/1996-1944/3/4/2801/ The direct conversion of concentrated high temperature solar heat into electrical energy was demonstrated with a series of four–leg thermoelectric oxide modules (TOM). These temperature stable modules were not yet optimized for high efficiency conversion, but served as proof-of-principle for high temperature conversion. They were constructed by connecting two p- (La1.98Sr0.02CuO4) and two n-type (CaMn0.98Nb0.02O3) thermoelements electrically in series and thermally in parallel. The temperature gradient ΔT was applied by a High–Flux Solar Simulator source (HFSS) which generates a spectrum similar to solar radiation. The influence of the graphite layer coated on the hot side of the Al2O3 substrate compared to the uncoated surface on ΔT, Pmax and η was studied in detail. The measurements show an almost linear temperature profile along the thermoelectric legs. The maximum output power of 88.8 mW was reached for a TOM with leg length of 5 mm at ΔT = 622 K. The highest conversion efficiency η was found for a heat flux of 4–8 W cm-2 and the dependence of η on the leg length was investigated. http://www.mdpi.com/1996-1944/3/4/2801/ Thu, 15 Apr 2010 00:00:00 CEST Materials 2010-04-15 3 4 Article 2801 2814 1996-1944 Thermoelectric Oxide Modules (TOMs) for the Direct Conversion of Simulated Solar Radiation into Electrical Energy 2010-04-15 doi: 10.3390/ma3042801 Tomeš Trottmann Suter Aguirre Steinfeld Haueter Weidenkaff http://www.mdpi.com/1996-1944/3/4/2735/ A heat transfer model that couples radiation/conduction/convection heat transfer with electrical potential distribution is developed for a thermoelectric converter (TEC) subjected to concentrated solar radiation. The 4-leg TEC module consists of two pairs of p-type La1.98Sr0.02CuO4 and n-type CaMn0.98Nb0.02O3 legs that are sandwiched between two ceramic Al2O3 hot/cold plates and connected electrically in series and thermally in parallel. The governing equations for heat transfer and electrical potential are formulated, discretized and solved numerically by applying the finite volume (FV) method. The model is validated in terms of experimentally measured temperatures and voltages/power using a set of TEC demonstrator modules, subjected to a peak radiative flux intensity of 300 suns. The heat transfer model is then applied to examine the effect of the geometrical parameters (e.g. length/width of legs) on the solar-to-electricity energy conversion efficiency. http://www.mdpi.com/1996-1944/3/4/2735/ Wed, 14 Apr 2010 00:00:00 CEST Materials 2010-04-14 3 4 Article 2735 2752 1996-1944 Heat Transfer and Geometrical Analysis of Thermoelectric Converters Driven by Concentrated Solar Radiation 2010-04-14 doi: 10.3390/ma3042735 Suter Tomeš Weidenkaff Steinfeld http://www.mdpi.com/1996-1944/3/4/2606/ A series of (MS)1+x(TiS2)2 (M = Pb, Bi, Sn) misfit layer compounds are proposed as bulk thermoelectric materials. They are composed of alternating rock-salt-type MS layers and paired trigonal anti-prismatic TiS2 layers with a van der Waals gap. This naturally modulated structure shows low lattice thermal conductivity close to or even lower than the predicted minimum thermal conductivity. Measurement of sound velocities shows that the ultra-low thermal conductivity partially originates from the softening of the transverse modes of lattice wave due to weak interlayer bonding. Combined with a high power factor, the misfit layer compounds show a relatively high ZT value of 0.28~0.37 at 700 K. http://www.mdpi.com/1996-1944/3/4/2606/ Tue, 06 Apr 2010 00:00:00 CEST Materials 2010-04-06 3 4 Article 2606 2617 1996-1944 Low-Thermal-Conductivity (MS)1+x(TiS2)2 (M = Pb, Bi, Sn) Misfit Layer Compounds for Bulk Thermoelectric Materials 2010-04-06 doi: 10.3390/ma3042606 Wan Wang Wang Koumoto http://www.mdpi.com/1996-1944/3/3/1509/ We report resistivity and thermo-electric power measurements of the anatase phase of TiO2under pressure up to 2.3 GPa. Despite its transparent appearance, the single crystal of anatase exhibits a metallic-like resistivity above 60 K, at all pressures. The rather high value of the thermo-electric power at room temperature points to complex transport mechanism in this phase. http://www.mdpi.com/1996-1944/3/3/1509/ Mon, 01 Mar 2010 00:00:00 CET Materials 2010-03-01 3 3 Article 1509 1514 1996-1944 High-Pressure Study of Anatase TiO2 2010-03-01 doi: 10.3390/ma3031509 Jaćim Jaćimović Cristian Vâju Richard Gaál Arnaud Magrez Helmuth Berger László Forró http://www.mdpi.com/1996-1944/3/2/786/ We show why and how the spin state of transition-metal ions affects the thermoelectric properties of transition-metal oxides by investigating two perovskite-related oxides. In the A-site ordered cobalt oxide Sr3YCo4O10.5, partial substitution of Ca for Sr acts as chemical pressure, which compresses the unit cell volume to drive the spin state crossover, and concomitantly changes the magnetization and thermopower. In the perovskite rhodium oxide LaRhO3, partial substitution of Sr for La acts as hole-doping, and the resistivity and thermopower decrease systematically with the Sr concentration. The thermopower remains large values at high temperatures (>150 μV/K at 800 K), which makes a remarkable contrast to La1-xSrxCoO3. We associate this with the stability of the low spin state of the Rh3+ ions. http://www.mdpi.com/1996-1944/3/2/786/ Wed, 27 Jan 2010 00:00:00 CET Materials 2010-01-27 3 2 Article 786 799 1996-1944 Spin State Control of the Perovskite Rh/Co Oxides 2010-01-27 doi: 10.3390/ma3020786 Ichiro Terasaki Soichiro Shibasaki Shin Yoshida Wataru Kobayashi http://www.mdpi.com/1996-1944/3/1/318/ Polycrystalline bulk copper aluminate Cu1-x-yAgxByAlO2 with B = Ni or Zn were prepared by spark plasma sintering and subsequent thermal treatment. The influence of partial substitution of Ag, Ni and Zn for Cu-sites in CuAlO2 on the high temperature thermoelectric properties has been studied. The addition of Ag and Zn was found to enhance the formation of CuAlO2 phase and to increase the electrical conductivity. The addition of Ag or Ag and Ni on the other hand decreases the electrical conductivity. The highest power factor of 1.26 × 10-4 W/mK2 was obtained for the addition of Ag and Zn at 1,060 K, indicating a significant improvement compared with the non-doped CuAlO2 sample. http://www.mdpi.com/1996-1944/3/1/318/ Mon, 11 Jan 2010 00:00:00 CET Materials 2010-01-11 3 1 Article 318 328 1996-1944 The Effect of (Ag, Ni, Zn)-Addition on the Thermoelectric Properties of Copper Aluminate 2010-01-11 doi: 10.3390/ma3010318 Shun-ichi Yanagiya Ngo Van Nong Jianxiao Xu Nini Pryds