Browsing Τμήμα Μηχανικών Μηχανολογίας και Κατασκευαστικής / Department of Mechanical and Manufacturing Engineering by Author "Paraskevopoulos, K. M."

Now showing items 1-20 of 37

    • 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 ...
    • 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  

      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 sintering in ball-milled K 2Bi 8Se 13 thermoelectric nano-composites 

      Hatzikraniotis, E.; Ioannou, M.; Chrissafis, K.; Chung, D. Y.; Paraskevopoulos, K. M.; Kyratsi, Theodora (2012)
      K 2Bi 8Se 13 has many attractive features for thermoelectric applications. Recently, K 2Bi 8Se 13-based nanocomposite materials, consisting of nano-crystalline, micro-crystalline and amorphous phases, have been fabricated ...
    • Article  

      Efficiency study of a commercial thermoelectric power generator (TEG) under thermal cycling 

      Hatzikraniotis, E.; Zorbas, K. T.; Samaras, I.; Kyratsi, Theodora; Paraskevopoulos, K. M. (2010)
      Thermoelectric generators (TEGs) make use of the Seebeck effect in semiconductors for the direct conversion of heat to electrical energy. The possible use of a device consisting of numerous TEG modules for waste heat ...
    • Conference Object  

      Experimental and modeling evidence for the reduction of thermal conductivity in Mg2Si by fine tuning the nano & micro-structural features 

      Hatzikraniotis, E.; Polymeris, G. S.; Symeou, E.; Kyratsi, Theodora; Paraskevopoulos, K. M. (Elsevier Ltd, 2017)
      In this paper, experimental and modeling evidence for reduced thermal conductivity in Bi-doped Mg2Si is presented. Upon doping, lattice thermal conductivity was reduced monotonically and, at the same time, MgO content was ...
    • Article  

      Fabrication of nanocrystalline Mg 2Si via ball milling process: Structural studies 

      Ioannou, M.; Hatzikraniotis, E.; Lioutas, C.; Hassapis, T.; Altantzis, T.; Paraskevopoulos, K. M.; Kyratsi, Theodora (2012)
      In this work, nanocrystalline Mg 2Si material was fabricated via wet ball milling process using n-hexane as process control agent. Milling parameters, with emphasis on milling time and ball size, and conditions were studied ...
    • Conference Object  

      FTIR Reflectivity spectra of Thermoelectric K2Sb 8Se13 crystals 

      Hatzikraniotis, E.; Hassapis, Th; Kyratsi, Theodora; Paraskevopoulos, K. M.; Kanatzidis, M. G. (Affiliation: Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, GreeceAffiliation: Department of Mechanical and Manufacturing Engineering, University of CyprusAffiliation: Department of Chemistry, Michigan State University, MI 48824, United StatesCorrespondence Address: Hatzikraniotis, E.Physics Department, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece, 2006)
      Investigations of ternary and quaternary compounds, Bi and Sb chalcogenides, have shown that several multinary compounds containing alkali metals present promising thermoelectric properties. In this work, the FTIR reflectivity ...
    • 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 ...
    • Article  

      Inhomogeneities and Effective Mass in Doped Mg2Si 

      Stefanaki, E. C.; Polymeris, G. S.; Ioannou, M.; Pavlidou, E.; Hatzikraniotis, E.; Kyratsi, Theodora; Paraskevopoulos, K. M. (2016)
      Magnesium silicide (Mg2Si)-based materials are promising candidates as thermoelectric components for mid-temperature range (500–900 K) energy conversion. Many different approaches for determining the parabolicity of the ...
    • Conference Object  

      IR reflectivity studies of mechanically alloyed PbTe nanocrystals 

      Hasapis, T. Ch; Papageorgiou, C.; Hatzikraniotis, E.; Kyratsi, Theodora; Paraskevopoulos, K. M. (Affiliation: Department of Physics, Aristotle University of Thessaloniki, 54123 Thessaloniki, GreeceAffiliation: Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1678 Nicosia, CyprusCorrespondence Address: Hasapis, T. Ch.Department of Physics, Aristotle University of Thessaloniki, 54123 Thessaloniki, Greece, 2009)
      Nano-crystalline lead telluride powder was synthesized by mechanical alloying using a high-energy planetary ball mill. The broadening of the X-ray diffraction peaks vs ball milling time, indicates small crystalline size ...
    • Article  

      KSb5S8: A wide bandgap phase-change material for ultra high density rewritable information storage 

      Kyratsi, Theodora; Chrissafis, K.; Wachter, J.; Paraskevopoulos, K. M.; Kanatzidis, M. G. (2003)
      The reversible glassformation and glass crystallization properties of KSb3S8 was described. On the basis of glass transition and crystallization kinetics of KSb5S8, it was found that the crystallization rate and assoicated ...
    • 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 ...
    • Conference Object  

      Long-term performance of a commercial thermoelectric power generator 

      Hatzikraniotis, E.; Zorbas, K.; Kyratsi, Theodora; Paraskevopoulos, K. M. (Affiliation: Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, GreeceAffiliation: Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, CyprusCorrespondence Address: Hatzikraniotis, E.Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki, Greece, 2009)
      In this work, thermoelectric device was made, using a commercially available ThermoElectric Generator (TEG), in order to measure the gained power and efficiency for long- term performance. The module was subjected to ...
    • Article  

      Macro and Micro-Scale Features of Thermoelectric PbTe (Br, Na) Systems: Micro-FTIR Spectroscopy, Micro-Seebeck Measurements, and SEM/EDX Observations 

      Stefanaki, E. C.; Polymeris, G. S.; Nikolic, P. M.; Papageorgiou, C.; Pavlidou, E.; Hatzikraniotis, E.; Kyratsi, Theodora; Paraskevopoulos, K. M. (2014)
      In this work, n-type and p-type PbTe doped with Br and Na, respectively, were thoroughly examined to determine the effect of the dopant on microstructure. Macro and micro homogeneity of the samples were studied by means ...
    • Conference Object  

      Mechanical alloying synthesis of K2Bi8Se 13- type solid solutions 

      Toumpas, N.; Kyratsi, Theodora; Hatzikraniotis, E.; Tsiappos, A.; Pavlidou, E.; Paraskevopoulos, K. M.; Chung, D. Y.; Kanatzidis, M. G. (Affiliation: Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, 1678, CyprusAffiliation: Department of Physics, Aristotle University of Thessaloniki, Thessaloniki, 54124, GreeceAffiliation: Materials Science Division, Argonne National Laboratory, Argonne, IL 60439, United StatesAffiliation: Department of Chemistry, Northwestern University, Evanston, IL 60208, United StatesCorrespondence Address: Toumpas, N.Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia, 1678, Cyprus, 2008)
      Solid solutions of β-K2Bi8-xSb xSe13 are an interesting series of materials for thermoelectric investigations due to their very low thermal conductivity and highly anisotropic electrical properties. In this work, we aimed ...
    • 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 ...