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  • 1.
    Carvalho, A.
    et al.
    University of Exeter.
    Jones, R.
    University of Exeter.
    Janke, C.
    University of Exeter.
    Öberg, Sven
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Briddon, P.R.
    University of Newcastle Upon Tyne.
    Primary defects in n-type irradiated germanium: a first-principles investigation2008Ingår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 131-133, s. 253-258Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The properties of point defects introduced by low temperature electron irradiation of germanium are investigated by first-principles modeling. Close Frenkel pairs, including the metastable fourfold coordinated defect, are modelled and their stability is discussed. It is found that damage evolution upon annealing below room temperature can be consistently explained with the formation of correlated interstitial-vacancy pairs if the charge-dependent properties of the vacancy and self-interstitial are taken into account. We propose that Frenkel pairs can trap up to two electrons and are responsible for conductivity loss in n-type Ge at low temperatures.

  • 2.
    Forouzan, Farnoosh
    et al.
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Gunasekaran, Suresh
    Hedayati, Ali
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Energivetenskap.
    Vuorinen, Esa
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Mücklich, Frank
    Department for Materials Science, Functional Materials, Saarland University, D-66041 Saarbrücken, Germany.
    Microstructure analysis and mechanical properties of Low alloy High strength Quenched and Partitioned Steel2017Ingår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 258, s. 574-578Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Gleeble study of the quenching and partitioning (Q&P) process has been performed onDomex 960 steel (Fe, 0.08 %C, 1.79 %Mn, 0.23 %Si, 0.184 %Ti, and 0.038 %Al). The effect ofdifferent Q&P conditions on microstructure and mechanical properties were investigated. The aimof the process is to produce a fine grained microstructure for better ductility and controlled amountsof different micro-constituents to increase the strength and toughness simultaneously. Threedifferent quenching temperatures, three partitioning temperatures and three partitioning times havebeen selected to process the 27 specimens by Gleeble® 1500. The specimens were characterized bymeans of OM, SEM, XRD, hardness and impact tests. It was found that, fine lath martensite withretained austenite is achievable without high amount of Si or Al in the composition although lack ofthese elements may cause the formation of carbides and decrease the available amount of carbon forpartitioning into the austenite. The hardness increases as the quenching temperature is decreased,however, at highest partitioning temperature (640◦C) the hardness increases sharply due to extensiveprecipitate formation.

  • 3.
    Fujita, N.
    et al.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Eberlein, T. A. G.
    Öberg, Sven
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Briddon, P. R.
    School of Natural Science, University of Newcastle upon Tyne.
    Theoretical aspects on the formation of the tri-interstitial nitrogen defect in silicon2008Ingår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 131-133, s. 265-269Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this paper we investigate the formation of interstitial nitrogen trimers N3 which have been suggested as a fast-diffusing species in silicon recently. Out-diffusion profiles of nitro-gen show the involvement of at least two independent nitrogen related defects in the diffusion process depending on the nitrogen concentration at different depths of the sample. When the nitrogen concentration is small it is proposed that nitrogen trimers are formed in a two step process. We present the structural properties of such a defect using density functional theory and examine the energetics of the two proposed reactions leading to the formation of N3.

  • 4.
    Fujita, N.
    et al.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Goss, J.P.
    School of Natural Science, University of Newcastle upon Tyne.
    Frauenheim, T.
    Department of Physics, University of Paderborn.
    Öberg, Sven
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Briddon, P.R.
    School of Natural Science, University of Newcastle upon Tyne.
    Theoretical investigations of the diffusion of nitrogen-pair defects in silicon2005Ingår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 108, s. 407-12Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The formation of oxygen precipitates and microvoids as well as the movement and growth of dislocations are strongly affected by the presence of nitrogen. However, the diffusion mechanism of nitrogen is unclear with several conflicting reports in the literature. Here, ab initio density functional theory is used to investigate diffusion mechanisms of the nitrogen-pair defect in silicon. We find a new metastable nitrogen-pair defect structure, which is lower in energy than any structures previously considered as intermediate structures in the minimum energy paths. Thus, by including this new metastable structure, we suggest a more likely, alternative reaction path whose barrier is 2.69 eV. This is compared with experimental barriers

  • 5.
    Fujita, N.
    et al.
    School of Physics, University of Exeter.
    Jones, R.
    School of Physics, University of Exeter.
    Öberg, Sven
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Briddon, P. R.
    School of Natural Science, University of Newcastle upon Tyne.
    Blumenau, A. T.
    Max-Planck-Institut für Eisenforschung GmbH.
    A theoretical study of copper contaminated dislocations in silicon2008Ingår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 131-133, s. 259-264Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Recently, the interaction of copper with dislocations in p-type Si/SiGe/Si structures has been investigated experimentally and a new dislocation related DLTS-level at Ev +0.32 eV was detected after intentional contamination with copper. To determine the origin of this newly detected level, in this work we present first density functional calculations of substitutional copper at 90◦ and 30◦ partial dislocations in silicon. Defect-dislocation binding energies are determined and electrical gap levels are calculated and compared with the experimental data. As a result, the observed level at Ev + 0.32 eV is tentatively assigned to the single acceptor level of substitutional copper at the dislocation.

  • 6.
    Ghassa, S.
    et al.
    University of Tehran, Tehran, Iran .
    Abdollahi, H.
    University of Tehran, Tehran, Iran .
    Gharabaghi, M.
    University of Tehran, Tehran, Iran .
    Chelgani, Saeed Chehreh
    University of Michigan, Ann Arbor, Michigan, USA.
    Jafari, M.
    University of Tehran, Tehran, Iran .
    The surface chemistry characterization of pyrite, sphalerite and molybdenite after bioleaching2017Ingår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 262 SSP, s. 487-491Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The mineral surface chemistry characterization is essential to describe the dissolution kinetics in leaching and bioleaching. Five different methods, including X-ray diffraction (XRD), Scanning Electron Microscopy (SEM), Energy-Dispersive X-ray Spectroscopy (EDS), Fourier Transform Infrared Spectroscopy (FTIR) and Raman Spectroscopy, have been applied to study the surface chemistry changes during pyrite, sphalerite and molybdenite bioleaching. The surface characterizations have been done for samples before and after biological and chemical leaching. The SEM images illustrated that the minerals surfaces were smooth before processing, while they covered with an ash layer after biological treatment. Although EDS analysis and Raman spectrum demonstrated the potassium jarosite formation on the pyrite surface during bioleaching, the formation of jarosite layer did not occur on the sphalerite surfaces during bioleaching. On the other hand, a sulfur layer formation on the sphalerite surface was confirmed by mentioned characterization methods. Finally, according to the XRD and EDS spectrum the molybdenite surface had been covered both with sulfur and jarosite.

  • 7.
    Jafari, M.
    et al.
    University of Tehran, Tehran, Iran.
    Shafaei, S. Z.
    University of Tehran, Tehran, Iran.
    Abdollahi, H.
    University of Tehran, Tehran, Iran.
    Gharabaghi, M.
    University of Tehran, Tehran, Iran.
    Chelgani, Saeed Chehreh
    Luleå tekniska universitet, Institutionen för samhällsbyggnad och naturresurser, Mineralteknik och metallurgi. University of Michigan, Ann Arbor, USA.
    Ghassa, S.
    University of Tehran, Tehran, Iran.
    Examining the effects of typical reagents for sulfide flotation on bio-oxidation activity of ferrous iron oxidizing microorganisms2017Ingår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 262 SSP, s. 84-87Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mineral separation by froth flotation is widely used around the world for the beneficiation of sulfide ores. Flotation products (typically concentrate) are subjected to metallurgical processes for metal extractions. Bioleaching as a metallurgical procedure indicated many advantages over other traditional techniques (pyro- and hydro-metallurgy). However, organic flotation reagent residuals on the surface of minerals are effective on biological activities of microorganisms. In this work, to extensively study these effects, typical sulfide flotation collectors (Sodium ethyl-xanthate, Potassium isopropyl-xanthate, Potassium isobutyl-xanthate, Potassium amyl-xanthate, and Dithiophosphate (Aero)), and frothers (pine oil (PO) and methyl isobutyl Carbinol (MIBC)) were used in the presence of various bacteria (Acidithiobacillus ferrooxidans and Leptospirillum ferrooxidans) to investigate their effects on bio-oxidation. The results of this investigation can be used to better understand the mechanisms of bio-activities when reagent residues are on the surface of flotation products and they will feed to the bioleaching process.

  • 8.
    Jones, R.
    et al.
    School of Physics, University of Exeter.
    Carvalho, A.
    Department of Physics, University of Aveiro.
    Coutinho, J.
    Department of Physics, University of Aveiro.
    Torres, V.J.B.
    Department of Physics, University of Aveiro.
    Öberg, Sven
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Briddon, P.R.
    School of Natural Science, University of Newcastle upon Tyne.
    Theoretical investigations of the energy levels of defects in germanium2005Ingår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 108-109, s. 697-702Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The donor and acceptor levels of defects in Ge as well as in Si are found using a local density functional method applied to large H-terminated defective clusters. The surfaces of the clusters are modified so that their band gaps are aligned with experimental values. It is shown that the resulting energies of the first donor and acceptor levels are within about 0.2 eV of the experimental values

  • 9.
    Markevich, Vladimir P.
    et al.
    Photon Science Institute, University of Manchester.
    Peaker, Anthony R.
    Photon Science Institute, University of Manchester.
    Hamilton, Btruce
    Photon Science Institute, University of Manchester.
    Lastovskiǐ, S.B.
    State Scientific and Production Association, Scientific-Practical Materials Research Centre of the National Academy of Sciences of Belarus.
    Murin, Leonid I.
    State Scientific and Production Association, Scientific-Practical Materials Research Centre of the National Academy of Sciences of Belarus.
    Coutinho, José A.
    I3N, Department of Physics, University of Aveiro.
    Rayson, Mark
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Briddon, P.R.
    School of Electrical, Electronic and Computer Engineering, University of Newcastle upon Tyne.
    Svensson, Bengt Gunnar
    Department of Physics, Oslo University.
    The trivacancy and trivacancy-oxygen family of defects in silicon2014Ingår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 205-206, s. 181-190Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The data obtained recently from combined deep-level-transient spectroscopy (DLTS), local vibrational mode (LVM) spectroscopy and ab-initio modeling studies on structure, electronic properties, local vibrational modes, reconfiguration and diffusion paths and barriers for trivacancy (V3) and trivacancy-oxygen (V3O) defects in silicon are summarized. New experimental results on the introduction rates of the divacancy (V2) and trivacancy upon 4 MeV electron irradiation and on the transformation of V3 from the fourfold coordinated configuration to the (110) planar one upon minority carrier injection are reported. Possible mechanisms of the transformation are considered and discussed.

  • 10. Markevich, Vladimir P.
    et al.
    Peaker, Anthony R.
    Hamilton, Bruce
    Litvinov, Valentin V.
    Pokotilo, Yurii M.
    Petukh, Alla N.
    Lastovskii, Stanislav B.
    Coutinho, Jose
    Rayson, Mark
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Briddon, Patrick R.
    Radiation-induced defect reactions in tin-doped Ge crystals2011Ingår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 178 - 179, s. 392-397Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We have recently shown that Sn impurity atoms are effective traps for vacancies (V) in Ge:Sn crystals irradiated with MeV electrons at room temperature [V.P. Markevich et al., J. Appl. Phys. 109 (2011) 083705]. A hole trap with 0.19 eV activation energy for hole emission to the valence band (Eh) has been assigned to an acceptor level of the Sn-V complex. In the present work electrically active defects introduced into Ge:Sn+P crystals by irradiation with 6 MeV electrons and subsequent isochronal annealing in the temperature range 50-300 oC have been studied by means of transient capacitance techniques and ab-initio density functional modeling. It is found that the Sn-V complex anneals out upon heat-treatments in the temperature range 50-100 oC. Its disappearance is accompanied by the formation of vacancy-phosphorus (VP) centers. The disappearance of the VP defect upon thermal annealing in irradiated Sn-doped Ge crystals is accompanied by the effective formation of a defect which gives rise to a hole trap with Eh = 0.21 eV and is more thermally stable than other secondary radiation-induced defects in Ge:P samples. This defect is identified as tin-vacancy-phosphorus (SnVP) complex. It is suggested that the effective interaction of the VP centers with tin atoms and high thermal stability of the SnVP complex can result in suppression of transient enhanced diffusion of phosphorus atoms in Ge.

  • 11.
    Markevich, V.P.
    et al.
    Institute of Solid State and Semiconductor Physics, Minsk.
    Murin, L.I.
    Institute of Solid State and Semiconductor Physics, Minsk.
    Lastovskij, S.B.
    Institute of Solid State and Semiconductor Physics, Minsk.
    Medvedeva, L.R.
    Institute of Solid State and Semiconductor Physics, Minsk.
    Lindström, J.L.
    Lund University, Division of Solid State Physics.
    Peaker, A.R.
    Centre for Electronic Materials, Devices and Nanostructures, University of Manchester.
    Coutinho, J.
    Department of Physics, University of Aveiro, Campus Santiago.
    Jones, R.
    School of Physics, University of Exeter.
    Torres, V.J.B.
    Department of Physics, University of Aveiro, Campus Santiago.
    Öberg, Sven
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Matematiska vetenskaper.
    Briddon, P.R.
    School of Natural Science, University of Newcastle upon Tyne.
    Electronic properties and structure of a complex incorporating a self-interstitial and two oxygen atoms in silicon2005Ingår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 108, s. 273-278Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The electronic properties and structure of a complex incorporating a self-interstitial (I) and two oxygen atoms are presented by a combination of deep level transient spectroscopy (DLTS), infrared absorption spectroscopy and ab-initio modeling studies. It is argued that the IO2 complex in Si can exist in four charge states (IO2-, IO20, IO2+, and IO2++). The first and the second donor levels of the IO2 complex show an inverted location order in the gap, leading to a E(0/ ++) occupancy level at Ev + 0.255 eV. Activation energies for hole emission, transformation barriers between different structures, and positions of LVM lines for different configurations and charge states have been determined. These observables were calculated by density-functional calculations, which show that they are accounted for if we consider at least two charge-dependent defect structures.

  • 12.
    Wang, Yan Dong
    et al.
    Institute of New Materials Technology, Northeastern University, Shenyang.
    Peng, Ru Lin
    Studsvik Neutron Research Laboratory, Uppsala University.
    Almer, Jon
    Advanced Photon Source (APS), Argonne National Laboratory, Argonne.
    Odén, Magnus
    Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, Materialvetenskap.
    Liu, Y.D.
    Institute of New Materials Technology, Northeastern University, Shenyang.
    Zou, Liang
    Institute of New Materials Technology, Northeastern University, Shenyang.
    Determination of grain-orientation-dependent stress in coatings2005Ingår i: Solid State Phenomena, ISSN 1012-0394, E-ISSN 1662-9779, Vol. 105, s. 107-112Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Quantitative interpretations of the so-called non-linear lattice strain distributions observed in coatings and thin films are important not only for determining the macro-and micro-stress fields, but also for inferring the active mechanisms of grain interactions during various deposition processes. In this paper, we present a method, which determines simultaneously both the macro-and micro-stress fields in the coatings and thin films. This method is extended from the previous stress-orientation distribution function (SODF) analysis method, which has already been used for residual stress analysis in bulk materials subjected to rolling and fatigue deformation. The validity of analysis method is demonstrated through measurements of lattice strains by high-energy x-ray and analysis of grain-orientation-dependent stresses in a CrN coating.

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