Browsing by Subject "Doping (additives)"

Now showing items 1-20 of 21

    • Article  

      Determination of Erbium Distribution in Optical Fibers Using Confocal Optical Microscopy 

      Uttamchandani, D.; Othonos, Andreas S.; Hubert, M. (1994)
      Confocal fluorescence microscopy has been used to detect the 565 nm wavelength fluorescence generated from Er+3 ions present in erbium doped optical fibers, thereby enabling the concentration profile of these ions in the ...
    • 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 ...
    • Article  

      The effect of La3+, Ti4+ and Zr4+ dopants on the mechanism of WGS on ceria-doped supported Pt catalysts 

      Petallidou, Klito C.; Kalamaras, Christos M.; Efstathiou, Angelos M. (2014)
      Platinum nanoparticles supported on single CeO2 and TiO 2 metal oxides and Ce0.8Ti0.2O 2-δ solid solution were prepared to investigate the effect of Ti4+-doping of ceria on important mechanistic and kinetic aspects of the ...
    • Article  

      Effects of Ge concentration, boron co-doping, and hydrogenation on fiber bragg grating characteristics 

      Konstantaki, M.; Tamiolakis, Q.; Argyris, A.; Othonos, Andreas S.; Ikiades, A. (2005)
      In this paper, we compare photosensitivity, refractive-index modulation depth, spectral bandwidth, and excess loss through the inscription of fiber Bragg gratings in unloaded and hydrogen-loaded fibers with low- or ...
    • Article  

      Effects of W6+ doping of TiO2 on the reactivity of supported Rh toward NO: Transient FTIR and mass spectroscopy studies 

      Chafik, T.; Efstathiou, Angelos M.; Verykios, Xenophon E. (1997)
      The transient adsorption and dissociation of NO over Rh supported on undoped and W6+-doped TiO2 in the temperature range of 25-450°C has been studied by FTIR and mass spectroscopy. It was found that at 25 °C three kinds ...
    • Conference Object  

      Fiber laser sensor array 

      Alavie, A. Tino; Karr, Shawn E.; Othonos, Andreas S.; Measures, Raymond M. (Publ by Society of Photo-Optical Instrumentation Engineers, 1993)
      An intracore Bragg grating and a broadband reflector are used as cavity end mirrors of a tunable Erbium-doped fiber laser where the Bragg grating serves the dual purpose of the tuning element and the sensor. This fiber ...
    • Article  

      Hall effect in detwinned single crystals of YBa2(Cu1-xZnx)3O7-δ in the mixed state 

      Schegolev, A. I.; Giapintzakis, John; Manson, J. T.; Ginsberg, D. M.; Dumler, I. (1996)
      The effect of zinc doping on the mixed-state Hall effect in detwinned single crystals of YBa2Cu3O7-δ has been studied. We observe a sign reveral of the Hall effect in crystals with a superconducting transition temperature ...
    • 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 ...
    • Article  

      Kinetics of methane oxidative coupling on zinc-doped titanium oxide 

      Efstathiou, Angelos M.; Boudouvas, D.; Vamvuka, Despina; Verykios, Xenophon E. (1992)
      A kinetic study of methane conversion to C2-hydrocarbons was conducted by cofeeding methane and oxygen at 1 bar total pressure over a series of zinc-doped TiO2 catalysts. The zinc dopant concentration was varied between 1 ...
    • 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  

      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 ...
    • 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 ...
    • Article  

      Pb doping of In2O3 and their conversion to highly conductive PbS/In2S3-3xO3x nanowires with infra red emission 

      Zervos, Matthew; Othonos, Andreas S.; Gianetta, V.; Nassiopoulou, Androula Galiouna (2016)
      We have grown Pb doped In2O3 nanowires at 800°C which have the cubic bixbyite crystal structure of In2O3 and contain orthorhombic α-PbO. These had resistances up to ≈10 Ω and exhibited photoluminescence at 2.5 eV but we ...
    • Article  

      Pb doping of In2O3 and their conversion to highly conductive PbS/In2S3-3xO3x nanowires with infra red emission 

      Zervos, Matthew; Othonos, A.; Gianetta, V.; Nassiopoulou, A. G. (2016)
      We have grown Pb doped In2O3 nanowires at 800°C which have the cubic bixbyite crystal structure of In2O3 and contain orthorhombic α-PbO. These had resistances up to ≈10 Ω and exhibited photoluminescence at 2.5 eV but we ...
    • Article  

      The selective oxidation of methane to C2-hydrocarbons over lithium-doped TiO2 catalysts 

      Papageorgiou, D.; Efstathiou, Angelos M.; Verykios, Xenophon E. (1994)
      The oxidative coupling of methane (OCM) to C2-hydrocarbons was studied on a series of lithiumdoped titania catalysts by cofeeding methane (PCH4 = 0.5 bar) and oxygen (Po2 = 0.07-0.16 bar) at 1 bar total pressure in the ...
    • Article  

      Sign reversal of the Hall effect in YBa2(Cu1-x)3O7-δ single crystals 

      Neiman, R. L.; Giapintzakis, John; Ginsberg, D. M.; Mochel, J. M. (1995)
      We have measured the in-plane Hall effect and in-plane resistivity of cobalt-doped YBa2Cu3O7-δ (YBCO) single-crystal samples. The concentration of cobalt ranged from 1 to 3%. As the applied field was varied, a sign reversal ...
    • Article  

      Spin-gap and antiferromagnetic correlations in low-dimensional PbNi2-xAxV2O8 compounds (A = Mg, Co) 

      Mastoraki, I.; Lappas, A.; Schneider, R.; Giapintzakis, John (2002)
      The effect of the impurity doping in the quantum-spin chains of the PbNi2V2O8 Haldane-gap compound is studied. We report elastic neutron scattering and bulk magnetic susceptibility measurements on the quasi-one-dimensional ...
    • Article  

      Thermoelectric properties of Mg2Si coatings deposited by pack cementation assisted process on heavily doped Si substrates 

      Stathokostopoulos, D.; Stefanaki, E. C.; Ioannou, M.; Polymeris, G. S.; Chaliampalias, D.; Pavlidou, E.; Kyratsi, Theodora; Paraskevopoulos, K. M.; Vourlias, G.; Hatzikraniotis, E. (2014)
      This work presents a study of structural and thermoelectric properties of Mg2Si coatings deposited on heavily doped p- and n-type Si substrates, at 650 C. The as-grown layers were smooth and uniform in thickness without ...
    • Conference Object  

      Transport properties of the doped thermoelectric material K2Bi8-xSbxSe13 

      Brazis, P. W.; Ireland, J. R.; Lane, M. A.; Kyratsi, Theodora; Chung, D. Y.; Kanatzidis, M. G.; Kannewurf, C. R. (Affiliation: Dept. of Electrical and Comp. Eng., Northwestern University, Evanston, IL 60208-3118, United StatesCorrespondence Address: Brazis, P.W.Dept. of Electrical and Comp. Eng., Northwestern University, Evanston, IL 60208-3118, United States, 2001)
      The synthesis, physicochemical, spectroscopic, and structural characterization of the compound β-K2Bi8Se13 has been previously reported. The results indicated that this material should be investigated further for possible ...
    • Article  

      Understanding the synergistic catalytic effect between la2O 3 and CaO for the CH4 Lean De-NOx reaction: Kinetic and mechanistic studies 

      Anastasiadou, T.; Loukatzikou, Loukia A.; Costa, Costas N.; Efstathiou, Angelos M. (2005)
      Doping of La2O3 crystallites with Ca2+ ions significantly enhances the intrinsic rate of NO reduction by CH4 in the presence of 5% O2 at 550°C compared to pure La 2O3 and CaO solids, while the opposite is true after doping ...