• Article  

      Bi/Sb distribution and its consequences in solid solution members of the thermoelectric materials K2Bi8-xSbxSe13 

      Kyratsi, Theodora; Chung, D. Y.; Kanatzidis, M. G. (2002)
      In an effort to understand the nature of mass fluctuations introduced when β-K2Bi8Se13 is alloyed with K2Sb8Se13 we determined the detailed crystal structures of two solid solutions of the type K2Bi8-xSbxSe13 with x=4.0 ...
    • Article  

      Carbon nanotube-reinforced crosslinked polyethylene pipes for geothermal applications: From synthesis to decomposition using analytical pyrolysis-GC/MS and thermogravimetric analysis 

      Roumeli, E.; Markoulis, A.; Kyratsi, Theodora; Bikiaris, D.; Chrissafis, K. (2014)
      Carbon nanotube reinforced crosslinked high density polyethylene (PEX) nanocomposites were synthesized for geothermal applications requiring higher polymer thermal conductivity and a comprehensive thermal decomposition ...
    • Conference Object  

      Crystal growth of ternary and quaternary alkali metal bismuth chalcogenides using Bridgman technique 

      Kyratsi, Theodora; Chung, D. Y.; Choi, K.-S.; Dick, J. S.; Chen, W.; Uher, C.; Kanatzidis, M. (Affiliation: Dept. of Chemistry, Center of Fundamental Mat. Research, Michigan State University, East Lansing, MI 48824-1322, United StatesCorrespondence Address: Kyratsi, T.Dept. of Chemistry, Center of Fundamental Mat. Research, Michigan State University, East Lansing, MI 48824-1322, United States, 2001)
      Our exploratory research in new thermoelectric materials has identified the ternary and quaternary bismuth chalcogenides β-K2Bi8Se13, K2.5Bi8.5Se14 and K1+xPb4-2xBi7+xSe15, to have promising properties for thermoelectric ...
    • Article  

      Effect of antimony-doping and germanium on the highly efficient thermoelectric Si-rich-Mg2(Si,Sn,Ge) materials 

      Vlachos, N.; Polymeris, G. S.; Manoli, M.; Hatzikraniotis, E.; Khan, A. U.; Lioutas, C. B.; Stefanaki, E. C.; Pavlidou, E.; Paraskevopoulos, K. M.; Giapintzakis, John; Kyratsi, Theodora (2017)
      Two series of materials (a) Mg2Si0.55-ySn0.4Ge0.05Sby, 0 ≤ y ≤ 0.0175 and (b) Mg2Si0.5875-xSn0.4GexSb0.0125, 0 ≤ x ≤ 0.20 have been developed and studied in terms of structural features and thermoelectric properties/performance. ...
    • Article  

      Effect of Bi-doping and Mg-excess on the thermoelectric properties of Mg2Si materials 

      Ioannou, M.; Polymeris, G. S.; Hatzikraniotis, E.; Paraskevopoulos, K. M.; Kyratsi, Theodora (2014)
      In this work, Bi-doped magnesium silicide compounds were prepared by applying a combination of both, short-time ball milling and heating treatment. The effect of Mg excess was also studied, aiming towards further improvement ...
    • Article  

      Effect of microstructure on the thermoelectric performance of La1−xSrxCoO3 

      Viskadourakis, Z.; Athanasopoulos, G. I.; Kasotakis, E.; Giapintzakis, John (2016)
      We present a case where the microstructure has a profound effect on the thermoelectric properties of oxide compounds. Specifically, we have investigated the effect of different sintering treatments on La1−xSrxCoO3 samples ...
    • Article  

      Electronic Structure and Thermoelectric Properties of Pseudoquaternary Mg2Si1-x-ySnxGey-Based Materials 

      Kutorasinski, K.; Tobola, J.; Kaprzyk, S.; Khan, A. U.; Kyratsi, Theodora (2014)
      A theoretical study is presented on complex pseudoternary Bi-doped Mg2Si1-x-ySnxGey materials, which have recently been revealed to reach high thermoelectric figures of merit (ZT) of ∼1.4. Morphological characterization ...
    • Article  

      Experimental determination of the absolute temperature modulation in photothermal microscopy of Y1Ba2Cu3O7 crystals 

      Studenmund, W. R.; Fishman, I. M.; Kino, G. S.; Giapintzakis, John (1997)
      We present a technique to experimentally determine the value of the temperature perturbation ST in photothermal microscopy. Knowledge of δT is necessary for proper analysis of the differential optical reflectivity (∂R/∂T) ...
    • Article  

      Heat channeling in extremely thin silicon-on-insulator devices: A simulation study 

      Orfanidou, C. M.; Giapintzakis, John (2013)
      Silicon-on-insulator (SoI) devices are particularly interesting for thermal management studies as they suffer from severe self-heating because of the very low and isotropic thermal conductivity of silicon dioxide that is ...
    • Article  

      Highly anisotropic crystal growth and thermoelectric properties of K 2Bi 8-xSb xSe 13 solid solutions: Band gap anomaly at low x 

      Kyratsi, Theodora; Dyck, J. S.; Chen, W.; Chung, D. Y.; Uher, C.; Paraskevopoulos, K. M.; Kanatzidis, M. G. (2002)
      The thermoelectric properties of solid solutions of the type β-K 2Bi 8-xSb xSe 13 (0<x<8) were studied with respect to thermal behavior, band gap variation, and charge transport properties as a function of x. At x values ...
    • Conference Object  

      Initial assessment of the thermoelectric properties for the mixed system K2-xRbxBi8Se13 

      Ireland, J. R.; Kyratsi, Theodora; Kanatzidis, M. G.; Kannewurf, C. R. (Affiliation: Dept. of Elec. and Comp. Engineering, Northwestern University, Evanston, IL 60208-3118, United StatesCorrespondence Address: Ireland, J.R.Dept. of Elec. and Comp. Engineering, Northwestern University, Evanston, IL 60208-3118, United States, 2002)
      In previous studies we have investigated the thermoelectric properties of undoped and doped compositions of β-K2Bi8Se13. The attempt to substitute Rb for K resulted in a different structure type, but with potentially useful ...
    • Article  

      La0.95Sr0.05Coo3: An efficient room-temperature thermoelectric oxide 

      Andrbulakis, J.; Migiakis, P.; Giapintzakis, John (2004)
      Electric resistivity, thermal conductivity, and the thermopower of polycrystalline Sr-doped LaCoO3 with composition La 0.9Sr0.5CoO3 were measured. The crystal structure of the synthesized powders was determined by x-ray ...
    • Article  

      Lattice thermal conductivity of K 2(Bi 1-zSb z) 8Se 13 solid solutions 

      Kyratsi, Theodora; Hatzikraniotis, E.; Paraskevopoulous, M.; Dyck, J. S.; Shin, H. K.; Uher, C.; Kanatzidis, M. G. (2004)
      The influence of the Bi/Sb partial substitution to the lattice thermal conductivity of the K 2(Bi 1-zSb z) 8Se 13 solid solution series was studied. The variation of the lattice thermal conductivity with comparison was ...
    • Article  

      Local structure and influence of bonding on the phase-change behavior of the chalcogenide compounds K1-xRbxSb5S8 

      Wachter, J. B.; Chrissafis, K.; Petkov, V.; Malliakas, C. D.; Bilc, D. I.; Kyratsi, Theodora; Paraskevopoulos, K. M.; Mahanti, S. D.; Torbrügge, T.; Eckert, H.; Kanatzidis, M. G. (2007)
      KSb5S8 and its solid solution analogs with Rb and Tl were found to exhibit a reversible and tunable glass→crystal→glass phase transition. Selected members of this series were analyzed by differential scanning calorimetry ...
    • Article  

      Low-temperature synthesis and thermoelectric properties of n-type PbTe 

      Papageorgiou, C.; Giapintzakis, John; Kyratsi, Theodora (2013)
      n-Type PbTe compounds were synthesized at temperatures as low as 430 C. After synthesis, the materials were ground, cold pressed and sintered at 600 C. The effect of this low-temperature synthesis on the structural features ...
    • Conference Object  

      Modeling of thermal conductivity in high performing thermoelectric materials 

      Hatzikraniotis, E.; Kyratsi, Theodora; Paraskevopoulos, K. M. (Institute of Physics Publishing, 2017)
      The enhanced TE-performance in Mg2Si-Mg2Sn based pseudo-binaries is presented, which is attributed to low thermal conductivity. Sn-Si alloying, reduces the lattice thermal conductivity due to mass fluctuation. Furthermore, ...
    • Article  

      Modification of thermoelectric properties using insertion techniques 

      Hatzikraniotis, E.; Kyratsi, Theodora; Chrissafis, K.; Paraskevopoulos, K. M. (1999)
      In this work is presented the application insertion techniques for the modification of the performance of thermoelectric materials. The results indicate that in cases as in Bi2Se3 compounds where insertion of foreign species ...
    • Conference Object  

      On the optical properties of thermoelectric alkali metal chalcogenide compounds 

      Hatzikraniotis, E.; Kyratsi, Theodora; Zorba, T.; Paraskevopoulos, K. M.; Kanatzidis, M. G. (Affiliation: Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, GreeceAffiliation: Department of Chemistry, Michigan State University, East Lansing, MI 48824, United StatesAffiliation: Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1678 Nicosia, CyprusCorrespondence Address: Hatzikraniotis, E.Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece, 2006)
      Solid solutions of K2Bi8-xSbxSe 13 is an interesting series of complex bismuth-chalcogenide compounds, which are attractive for thermoelectric investigations. The highly anisotropic structure in these compounds results in ...
    • Article  

      Optical probing of anisotropic heat transport in the quantum spin ladder Ca 9La 5Cu 24O 41 

      Otter, M.; Athanasopoulos, G.; Hlubek, N.; Montagnese, M.; Labois, M.; Fishman, D. A.; Haan, F. De; Singh, S.; Lakehal, D.; Giapintzakis, John; Hess, C.; Revcolevschi, A.; Loosdrecht, P. H. M. Van (2012)
      A transient thermal imaging technique is used to monitor heat diffusion at the surface of the antiferromagnetic spin ladder material Ca 9La 5Cu 24O 41. This material shows highly anisotropic thermal conductivity due to a ...
    • Article  

      Pulsed laser deposition and thermal characterization of Ni-doped La5Ca9Cu24O41 thin films 

      Athanasopoulos, G. I.; Pervolaraki, M.; Svoukis, E.; Androulakis, J.; Saint-Martin, R.; Revcolevschi, A.; Giapintzakis, John (2011)
      Highly b-axis oriented polycrystalline Ni-doped La5Ca 9Cu24O41 thin films have been grown on (0 0 1) SrTiO3 substrates using the pulsed laser deposition technique. EDX measurements have revealed nearly stoichiometric ...