• Article  

      A2Bi8Se13 (A = Rb, Cs), CsBi3.67Se6, and BaBi2Se4: New ternary semiconducting bismuth selenides 

      Iordanidis, L.; Brazis, P. W.; Kyratsi, Theodora; Ireland, J.; Lane, M.; Kannewurf, C. R.; Chen, W.; Dyck, J. S.; Uher, C.; Ghelani, N. A.; Hogan, T.; Kanatzidis, M. G. (2001)
      Rb2Bi8Se13 (I), Cs2Bi8Se13 (II), CsBi3.67Se6 (III), and BaBi2Se4 (IV) were synthesized by direct combination reactions of the A/Se (A = Rb, Cs, Ba) and Bi2Se3 at ≥650 °C. Their structures were determined by single-crystal ...
    • 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 dioxide storage in olivine basalts: Effect of ball milling process 

      Rigopoulos, Ioannis; Petallidou, Klito C.; Vasiliades, Michalis A.; Delimitis, A.; Ioannou, Ioannis; Efstathiou, A. M.; Kyratsi, Theodora (2015)
      The goal of this study is to propose a cost-effective method for the optimization of the ex situ carbonation of basaltic rocks. The ball milling process was applied to a sample of olivine basalt from the Troodos ophiolite ...
    • Article  

      Carbon dioxide storage in olivine basalts: Effect of ball milling process 

      Rigopoulos, Ioannis; Petallidou, Klito C.; Vasiliades, Michalis A.; Delimitis, A.; Ioannou, Ioannis; Efstathiou, A. M.; Kyratsi, Theodora (2015)
      The goal of this study is to propose a cost-effective method for the optimization of the ex situ carbonation of basaltic rocks. The ball milling process was applied to a sample of olivine basalt from the Troodos ophiolite ...
    • 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 ...
    • Article  

      Carbon sequestration via enhanced weathering of peridotites and basalts in seawater 

      Rigopoulos, I.; Harrison, A. L.; Delimitis, A.; Ioannou, I.; Efstathiou, A. M.; Kyratsi, Theodora; Oelkers, E. H. (2018)
      Enhanced weathering of mafic and ultramafic rocks has been suggested as a carbon sequestration strategy for the mitigation of climate change. This study was designed to assess the potential drawdown of CO2 directly from ...
    • Conference Object  

      Carrier mapping in thermoelectric materials 

      Polymeris, G. S.; Hatzikraniotis, E.; Stefanaki, E. C.; Pavlidou, E.; Kyratsi, Theodora; Paraskevopoulos, K. M.; Kanatzidis, M. G. (Affiliation: Physics Department, Aristotle University of Thessaloniki, GR- 54124, Thessaloniki, GreeceAffiliation: Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1678 Nicosia, CyprusAffiliation: Department of Chemistry, Northwestern University, 2145 North Sheridan Road, Evanston, IL 60208, United StatesCorrespondence Address: Physics Department, Aristotle University of Thessaloniki, GR- 54124, Thessaloniki, Greece, 2013)
      The application of micro-fourier transform infrared (FT1R) mapping analysis to thermoelectric materials towards identification of doping inhomogeneities is described. Micro-FTIR, in conjunction with fitting, is used as ...
    • Article  

      Changes in the electronic properties of Bi2X3 (X: Se, Te) single crystals due to intercalation 

      Kyratsi, Theodora; Hatzikraniotis, E.; Paraskevopoulos, K. M.; Chrissafis, K. (1997)
      Bi2Se3 and Bi2Te3 are layered semiconductors n-type and p-type, respectively, which belong to the family of thermoelectric materials. In this work we examine the insertion of Cu in Bi 2Te3 and Bi2Se3 single crystals through ...
    • 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  

      Crystal/glass phase change in KSb5S8 studied through thermal analysis techniques 

      Chrissafis, K.; Kyratsi, Theodora; Paraskevopoulos, K. M.; Kanatzidis, M. G. (2004)
      The reversible crystal-glass and glass-crystal transitions discovered in KSb5S8 were studied in detail with nonisothermal scanning calorimetry techniques. When cooled, molten KSb5S8 becomes a metastable glass, which can ...
    • Article  

      CsMBi3Te6 and CsM2Bi3Te7 (M = Pb, Sn): New thermoelectric compounds with low-dimensional structures 

      Hsu, K. F.; Chung, D. Y.; Lal, S.; Mrotzek, A.; Kyratsi, Theodora; Hogan, T.; Kanatzidis, M. G. (2002)
      The new materials CsPbBi3Te6 nad CsPb2Bi3Te7 were discovered through reactions of CsBi4Te6 with PbTe, whereas the isostructural materials CsSnBi3Te6 and CsSn2Bi3Te7 were discovered through corresponding reactions with SnTe. ...
    • Article  

      Design of ball-milling experiments on Bi2Te3 thermoelectric material 

      Kanatzia, A.; Papageorgiou, Ch; Lioutas, Ch; Kyratsi, Theodora (2013)
      In this work, factorial ball-milling experiments have been applied to Bi2Te3 material, for the first time, aiming to investigate the effect of the main process parameters on the structural features and thermoelectric ...
    • Article  

      Design, assembly and characterization of silicide-based thermoelectric modules 

      Skomedal, G.; Holmgren, L.; Middleton, H.; Eremin, I. S.; Isachenko, G. N.; Jaegle, M.; Tarantik, K.; Vlachos, N.; Manoli, M.; Kyratsi, Theodora; Berthebaud, D.; Truong, N. Y. Dao; Gascoin, F. (2016)
      Silicides have attracted considerable attention for use in thermoelectric generators due mainly to low cost, low toxicity and light weight, in contrast to conventional materials such as bismuth and lead telluride. Most ...
    • Conference Object  

      Doping and alloying trends in new thermoelectric materials 

      Loo, S.; Lal, S.; Kyratsi, Theodora; Chung, D. Y.; Hsu, K. F.; Kanatzidis, M. G.; Hogan, T. P. (Affiliation: Dept. of Elec. and Comp. Engineering, Michigan State University, East Lansing, MI, United StatesCorrespondence Address: Loo, S.Dept. of Elec. and Comp. Engineering, Michigan State University, East Lansing, MI, United States, 2002)
      New thermoelectric bulk materials such as CsBi4Te6 have shown superior properties to traditional materials, however, optimal performance requires continuing investigations of doping and alloying trends. A recently modified ...
    • Conference Object  

      Doping studies of n-type CsBi4Te6 thermoelectric materials 

      Lane, M. A.; Ireland, J. R.; Brazis, P. W.; Kyratsi, Theodora; Chung, D. Y.; Kanatzidis, M. G.; Kannewurf, C. R. (Affiliation: Dept of Electrical and Computer Eng., Northwestern University, Evanston, IL 60208, United StatesCorrespondence Address: Lane, M.A.Dept of Electrical and Computer Eng., Northwestern University, Evanston, IL 60208, United States, 2001)
      We have previously reported the successful p-type doping of CsBi4Te6 which had a high figure of merit at temperatures below 300 K. In this study, several dopants were explored to make n-type CsBi4Te6. A program of measurements ...
    • 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 ball milling on the carbon sequestration efficiency of serpentinized peridotites 

      Rigopoulos, I.; Delimitis, A.; Ioannou, I.; Efstathiou, A. M.; Kyratsi, Theodora (2018)
      Mineral carbonation has been suggested as a safe carbon capture and storage (CCS) strategy for the mitigation of climate change. This study investigates the effect of ball milling on the CO2 sequestration capacity of ...
    • 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  

      The Effect of Ge on Mg2Si0.6−x Sn0.4Ge x Materials 

      Vlachos, N.; Hatzikraniotis, E.; Mihailescu, C. N.; Giapintzakis, John; Kyratsi, Theodora (2014)
      In this work, we investigate the influence of the introduction of Ge on the thermoelectric properties of Bi-doped quaternary Mg2Si0.6−x Sn0.4Ge x alloys. Mg2Si0.58−x Sn0.4Bi0.02Ge x materials were fabricated by a low ...
    • Article  

      Effect of silicon nitride/oxide on the structure and the thermal conductivity of CoSi nanocomposites 

      Ioannou, M.; Delimitis, A.; Symeou, E.; Giapintzakis, John; Kyratsi, Theodora (2017)
      In this work, the fabrication of nanocomposites with silicon nitride/oxide into the thermoelectric matrix of cobalt silicide is presented. The different concentrations of nano-Si3N4 were intentionally introduced by mechanical ...