SwePub
Sök i SwePub databas

  Utökad sökning

Träfflista för sökning "swepub ;lar1:(umu);spr:eng;pers:(Sundqvist Bertil)"

Sökning: swepub > Umeå universitet > Engelska > Sundqvist Bertil

  • Resultat 1-10 av 351
Sortera/gruppera träfflistan
   
NumreringReferensOmslagsbildHitta
1.
  • Winter, Johannes, et al. (författare)
  • Charge transfer in alkali-metal-doped polymeric fullerenes
  • 1996
  • Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 54, s. 17486-17492
  • Tidskriftsartikel (refereegranskat)abstract
    • We present room-temperature Raman measurements of pressure-polymerized C60 and compare them with the spectra of RbC60 in the orthorhombic phase. Although both materials were prepared according to two completely different routes the spectra show a surprising similarity with respect to mode positions and line splitting. We concluded from this that both materials, the uncharged pressure-polymerized C60 and the rubidium-doped orthorhombic compound, have the same overall structure and the AC60 compounds can be considered as the doped species of the C60, polymerized using moderate low pressure and high temperatures. From a detailed comparison between both spectra mode shifting and line broadening as a consequence of the charge transfer was determined and electron-phonon coupling constants were estimated for the high-frequency Hg(7) and Hg(8) modes. The low values for the coupling constants compared to the ones in the K3C60 can explain the lack of superconductivity in the AC60 compounds.
  •  
2.
  • Aleksandrovskii, A. N., et al. (författare)
  • Negative thermal expansion of fullerite C60 at helium temperatures
  • 1997
  • Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 23:11, s. 943-946
  • Tidskriftsartikel (refereegranskat)abstract
    • The thermal expansion of fullerite C60 has been measured in the temperature range 2–9 K. A compacted fullerite sample with a diameter of about 6 mm and height of 2.4 mm was used. It was found that at temperatures below ~ 3.4 K the linear thermal expansion coefficient becomes negative. At temperatures above 5 K our results are in good agreement with the available literature data. A qualitative explanation of the results is proposed
  •  
3.
  • Aleksandrovskii, A. N., et al. (författare)
  • Thermal expansion of single-crystal fullerite C60 at helium temperatures
  • 2000
  • Ingår i: Low temperature physics (Woodbury, N.Y., Print). - : AIP Publishing. - 1063-777X .- 1090-6517. ; 26:1, s. 75-80
  • Tidskriftsartikel (refereegranskat)abstract
    • The thermal expansion of single-crystal fullerite C60 has been studied in the range of liquid-helium temperatures (2–10 K). At temperatures below ~4.5 K the thermal expansion of fullerite C60 becomes negative, in agreement with the previous results on polycrystalline materials. A qualitative explanation of the results is proposed.
  •  
4.
  • Andersson, Britt M., et al. (författare)
  • Electrical resistivity and critical temperature of Bi-based high-Tc superconductors to 1 GPa
  • 1990
  • Ingår i: High Pressure Research, volumes 3 to 5. - London : Gordon and Breach. - 2881247466 ; 3:1-6, s. 120-122
  • Konferensbidrag (refereegranskat)abstract
    • We have measured the electrical resistance R of a sintered, two-phase, high-TC superconductor with the nominal composition BiSrCaCu2Ox, as a function of T and p. We find d(lnR)/dp ≃ -0.06 GPa-1 at 295 K, while dTC/dp is 2.5 K/GPa for the phase with Tc ≃ 76 and 2 K/GPa for that with TC ≃ 106 K.
  •  
5.
  • Andersson, Britt M., et al. (författare)
  • Electrical transport properties of dense bulk YBa2Cu4O8 produced by hot isostatic pressing
  • 1990
  • Ingår i: Physica. C, Superconductivity. - 0921-4534 .- 1873-2143. ; 170:5-6, s. 521-531
  • Tidskriftsartikel (refereegranskat)abstract
    • Highly dense sintered YBa2Cu4O8 has been produced by hot isostatic pressing (HIP). The electrical resistivity varrho of this material has been measured as a function of temperature T and pressure varrho in the range 40–650 K and 0–0.7 GPa. Both the temperature dependence and the pressure dependence of varrho are found to be well described by a model based on the standard Bloch-Grüneisen theory. It is pointed out that varrho is liner in T only under isobaric conditions, while varrho is strongly nonlinear in all high-Tc superconductors under isochoric (constant volume) conditions. The critical current density of the material is 900 A/cm2 at 4 K, while the resistivity is 630 μΩ cm at 294 K.
  •  
6.
  • Andersson, Britt M., et al. (författare)
  • High-pressure properties of high-Tc superconductor samples produced by hot isostatic pressing
  • 1990
  • Ingår i: High Pressure Research, volumes 3 to 5. - London : Gordon and Breach. - 2881247466 ; 3:1-6, s. 123-125
  • Konferensbidrag (refereegranskat)abstract
    • The electrical resistance of dense YBa2Cu3Ox and YBa2Cu4Oy produced by hot isostatic pressing has been measured vs. T and p. At 295 K we find d (ln R)/dp ≃ -0.12 and -0.09 GPa-1, respectively, with no systematic dependence on initial density. For 1-2-4, dTC/dp ≃ 5.1 K/GPa, which is ten times that of 1-2-3.
  •  
7.
  • Andersson, Britt M., et al. (författare)
  • Thermal conductivity of polycrystalline YBa2Cu4O8
  • 1994
  • Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 49:6, s. 4189-4198
  • Tidskriftsartikel (refereegranskat)abstract
    • We have measured the thermal conductivity κ and the thermal diffusivity a of a dense bulk ceramic polycrystalline sample of YBa2Cu4O8 (1:2:4) in the temperature range 30–300 K. We find κ≊10 W m-1 K-1 at 100 K, significantly higher than in ceramic YBa2Cu3O7-δ (1:2:3) and approaching the in-plane value for single-crystal 1:2:3, and decreasing to 7.6 W m-1 K-1 at 300 K. The data for this sample can be described by standard theories for phonon thermal conductivity of crystalline materials with boundary, phonon, and electron scattering. The higher κ in 1:2:4 as compared to 1:2:3 is, in this model, due to the smaller point defect scattering in the former. The fitted parameters for the three scattering mechanisms all agree with independent estimates based on simple models; inserting data for electric resistivity, grain size, carrier density, and lattice properties we can predict κ and its T dependence to within about 20%. We also discuss models for the phonon and electron thermal conductivities in some detail, including some second-order effects such as inelastic electron scattering and a T-dependent carrier density.
  •  
8.
  • Andersson, Ove, et al. (författare)
  • Reorientational relaxation in C60 following a pressure induced change in the pentagon/hexagon equilibrium ratio
  • 1995
  • Ingår i: Physics Letters A. - : Elsevier Science B.V.. - 0375-9601 .- 1873-2429. ; 206:3-4, s. 260-264
  • Tidskriftsartikel (refereegranskat)abstract
    • The orientational structure of C60 depends on pressure and temperature. Pressurization below the glass transition temperature Tg can freeze in non-equilibrium orientational structures. The relaxation of such structures on heating through Tg has been studied through thermal conductivity measurements and the effects observed are explained in a simple model.
  •  
9.
  • Andersson, Ove, et al. (författare)
  • Thermal conductivity of C60 at pressures up to 1 GPa and temperatures in the range 50-300 K
  • 1996
  • Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 54:5, s. 3093-3100
  • Tidskriftsartikel (refereegranskat)abstract
    • The thermal conductivity λ of C60 shows anomalies near 260 K and 90 K which are associated with the well-established phase transition and glass transition, respectively. Both transition temperatures increase with pressure, at the rates 120 K GPa-1 and 62 K GPa-1, respectively. With increasing temperature, λ of the simple cubic (sc) phase increased below 170 K (glasslike behavior) but decreased above. The glasslike behavior of λ is probably due to a substantial amount of lattice defects. Possible reasons for the change of sign of dλ/dT near 170 K are discussed. In the face centered cubic (fcc) phase (T≳260 K at atmospheric pressure) λ was almost independent of temperature, a behavior which is far from that of an ordered crystal (λ∝T-1 for T≳Debye temperature). This result can be attributed to the molecular orientational disorder of the fcc phase. The relaxation behavior associated with the glassy state and its unusually strong dependence on thermal history are discussed briefly, and data which support a previously reported relaxation model are presented. At room temperature, the density dependencies of λ, (∂ lnλ/∂ lnρ)T, were 5.5 and 9.5 for the fcc and sc phases, which are values typical for an orientationally disordered phase and a normal crystal phase, respectively.
  •  
10.
  • Araujo, Carlos Moyses, et al. (författare)
  • Pressure-induced structural phase transition in NaBH4
  • 2005
  • Ingår i: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 72:5, s. 054125-
  • Tidskriftsartikel (refereegranskat)abstract
    • We present a combined experimental and theoretical study of the technologically important NaBH4 compound under high pressure. Using Raman spectroscopy at room temperature, we have found that NaBH4 undergoes a structural phase transformation starting at 10.0 GPa with the pure high-pressure phase being established above 15.0 GPa. In order to compare the Raman data recorded under high pressure with the low-temperature tetragonal phase of NaBH4, we have also performed a cooling experiment. The known order-disorder transition from the fcc to the tetragonal structure was then observed. However, the new high pressure phase does not correspond to this low-temperature structure. Using first-principle calculations based on the density functional theory, we show that the high-pressure phase corresponds to the alpha-LiAlH4–type structure. We have found a good agreement between the measured and calculated transition pressures. Additionally, we present the electronic structure of both the fcc and the high-pressure phases.
  •  
Skapa referenser, mejla, bekava och länka
  • Resultat 1-10 av 351
Typ av publikation
tidskriftsartikel (210)
konferensbidrag (123)
forskningsöversikt (7)
doktorsavhandling (4)
bokkapitel (4)
annan publikation (2)
visa fler...
proceedings (redaktörskap) (1)
visa färre...
Typ av innehåll
refereegranskat (324)
övrigt vetenskapligt/konstnärligt (24)
populärvet., debatt m.m. (3)
Författare/redaktör
Liu, Bingbing (59)
Yao, Mingguang (53)
Wågberg, Thomas (51)
Soldatov, Alexander (34)
Andersson, Ove (30)
visa fler...
Cui, Tian (29)
Zou, Guangtian (26)
Wang, Lin (23)
Jacobsson, Per (20)
Persson, Per-Axel (19)
McRae, Edward (18)
Esel'son, V.B. (17)
Dolbin, Alexander V. (16)
Gavrilko, V.G. (15)
Liu, Dedi (15)
Andersson, Britt M. (14)
Li, Quanjun (14)
Zou, Bo (14)
Lelaurain, Michelle (13)
Lundin, Anders (13)
Iwasiewicz-Wabnig, A ... (13)
Hou, Yuanyuan (13)
Talyzin, Alexandr (12)
Bäckström, Gunnar (12)
Makarova, Tatiana L. (12)
Liu, Ran (12)
Yu, Shidan (12)
Manzhelii, V. G. (11)
Andersson, Odd E. (11)
Cui, Wen (11)
Gadd, G.E. (10)
Moricca, S. (10)
Marêché, Jean-Franco ... (10)
Fransson, Åke (10)
Nyeanchi, Emmanuel B ... (10)
Launois, Pascale (10)
Vinnikov, N A (10)
Moret, Roger (10)
Cassidy, D. (9)
Blank, Vladimir D. (9)
Johnels, Dan (9)
Zhu, Xiaomei (8)
Dong, Jiajun (8)
Talyzin, Alexandr V. (7)
Liu, Bo (7)
Rapp, Östen (7)
Buga, Sergei G. (7)
Dubitsky, Gennadii A ... (7)
Serebryanaya, Nadejd ... (7)
visa färre...
Lärosäte
Luleå tekniska universitet (26)
Uppsala universitet (1)
Stockholms universitet (1)
Linköpings universitet (1)
Chalmers tekniska högskola (1)
Språk
Forskningsämne (UKÄ/SCB)
Naturvetenskap (336)
Teknik (16)
Samhällsvetenskap (2)
Medicin och hälsovetenskap (1)

År

Kungliga biblioteket hanterar dina personuppgifter i enlighet med EU:s dataskyddsförordning (2018), GDPR. Läs mer om hur det funkar här.
Så här hanterar KB dina uppgifter vid användning av denna tjänst.

 
pil uppåt Stäng

Kopiera och spara länken för att återkomma till aktuell vy