| 1. |
- Andersson, Henrik C. M., et al.
(författare)
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Creep testing of thick-wall copper electron beam and friction stir welds
- 2004
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Ingår i: Materials Research Society Symposium Proceedings. - 0272-9172 .- 1946-4274. - 1558997741 ; 824, s. 51-56
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Tidskriftsartikel (refereegranskat)abstract
- Thick section copper canisters are planned to be used as a corrosion protection of nuclear waste disposal containers for long term underground deposal in Sweden. The copper canisters will have the top and possibly the bottom lid welded to the canister walls using electron beam or friction stir welding. Due to the high external hydrostatic pressure and the relatively high temperature of the waste during the first one hundred years the copper will creep. The creep process will close the manufacturing gap between the cast iron container and the copper canister. The creep ductility must be sufficient to avoid cracking of the weld. Specimens cut from the friction stir welds and the electron beam welds have been creep tested at temperatures ranging from 75 to 175 degreesC. Cross-weld specimens were used for both friction stir and electron beam welds. Weld metal, heat affected zone and base metal were also studied for friction stir welds. The results for the electron beam welds show that the main creep deformation is concentrated to the weld metal where the failure takes place. Weld metal and most cross-weld tests of friction stir weld material show similar creep lives and ductility as base metal tests. Ductility at rupture was found to exceed 30% for friction stir weld specimens, and the Norton power law exponent was determined to be between 30 and 50.
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| 2. |
- Butorin, S. M., et al.
(författare)
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Resonant inelastic soft X-ray scattering studies of U(VI) reduction on iron surfaces
- 2004
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Ingår i: Materials Research Society Symposium Proceedings. - 0272-9172 .- 1946-4274. ; 807:Scientific Basis for Nuclear Waste Management XXVII, s. 113-118
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Tidskriftsartikel (refereegranskat)abstract
- The authors report on the spectroscopic anal. of several samples relevant to the processes governing the behavior of oxidized U species in groundwater solns. under anoxic conditions. Both Fe samples with different times of exposure to the U(IV) soln. and Fe metal-soln. interfaces in the liq. cell ex-situ and in-situ, resp. Resonant inelastic soft x-ray scattering is sensitive to the chem. state of U. The measurements were performed at a no. of energies of the primary photon beam across the U 5d absorption edge. The results unambiguously indicate the redn. of U(VI) to U(IV) on the Fe surface. [on SciFinder(R)]
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| 3. |
- Ericsson, Torsten, 1938-, et al.
(författare)
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Studies of residual stress, microcracks, hardness and microstructure of cold compacted metallic green bodies
- 2003
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Ingår i: Materials Research Society Symposium Proceedings. - 0272-9172 .- 1946-4274. ; 759, s. 53-64
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Tidskriftsartikel (refereegranskat)abstract
- The residual stresses have been measured by X-ray and neutron diffraction on PM green bodies manufactured by conventional and high speed compaction of iron powder with and without added copper and brass powder. Compressive residual stresses are present in a thin layer in both top and side surfaces. They are largest in the side surfaces due to plastic deformation of the surface material caused by the friction forces during ejection out of the die. In the interior of the green body residual stresses exist with certain region under compression (periferical regions) and other under tension (more central regions). It is unclear whether mixing iron powder with brass or copper powder leads to considerable phase stresses between the two phases.
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| 4. |
- Fors, Rickard, et al.
(författare)
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Comparison of Sol-Gel Derived and Pulsed Laser Deposited Epitaxial La0.67Ca0.33MnO3 Films for IR Bolometer
- 2004
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Ingår i: Mat. Res. Soc. Symp. Proc.. - : Springer Science and Business Media LLC. ; 811, s. E2.5.1-E2.5.6, s. 379-384
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Tidskriftsartikel (refereegranskat)abstract
- Epitaxial La0.67Ca0.33MnO3 films have been prepared on LaA1O3 crystals by pulsed laser deposition (PLD) and by a novel all-alkoxide sol-gel technique. Different out-of-plane lattice parameters are found for the as-prepared films, and scanning electron microscopy shows a more porous structure for sol-gel films as compared to PLD films. These differences are largely removed by post-annealing at 1000 °C. Transport measurements show maximum temperature coefficient of resistivity of 8.2 % K-1 at 258 K (PLD) and 6.1 % K-1 at 241 K (sol-gel) and :colossal magnetoresistance at 7 kOe of 35 % at 263 K (PLD) and 32 % at 246 K (sol-gel).
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| 5. |
- Grishin, Alexander, et al.
(författare)
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Electro-optical properties of Na0.5K0.5NbO3 films on Si by free-space coupling technique
- 2004
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Ingår i: New Materials For Microphotonics. - : Springer Science and Business Media LLC. - 1558997679 ; , s. 225-229
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Konferensbidrag (refereegranskat)abstract
- We report electro-optic performance of highly polar axis oriented Na0.5K0.5NbO3 (NKN) films grown directly on Pt(100nm)/Ti(10nm)/SiO2/Si(001) substrates by rf-magnetron sputtering. Semitransparent gold electrodes (diameter circle divide = 2 mm) were deposited ontop the NKN films by a thermal evaporation through the contact mask. Processing parameters have been specially optimized to obtain "electrosoft" NKN films with a non-linear fatigue-free P-E characteristics: low remnant P-r = 3.6 muC/cm(2) and high induced polarization P = 26 muC/cm(2) @ 522 kV/cm, and the coercive field E-c = 39 kV/cm. Electro-optical characterization of NKN/Pt/Si films has been performed using waveguide refractometry: a free-space coupling of a light beam into the thin-film waveguide modes. Intensity of TM- and TE-polarized light of 670 nm laser diode reflected from the free surface of NKN film and Au-cladding NKN/PL/Si waveguide was recorded at zero and 30 V (100 kV/cm) bias electric field. Extraordinary and ordinary refractive indices as well as electro-optic coefficient have been determined by fitting these experimental data to the Fresnel formulas. Applying 160 V (530 kV/cm) across the parallel plate NKN capacitor (circle divide = 2 mm, thickness 3 mum), modulation of the reflected light as high as 40% was achieved.
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| 6. |
- Grishin, Alexander M., et al.
(författare)
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Epitaxial La-0.67(Sr,Ca)(0.33)MnO3 films on Si for IR bolometer applications
- 2004
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Ingår i: Integration Of Advanced Micro-And Nanoelectronic Devices-Critical Issues And Solutions. - : Springer Science and Business Media LLC. - 155899761X ; , s. 405-410
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Konferensbidrag (refereegranskat)abstract
- We report on processing and properties of La-0.67(Sr,Ca)(0.33)MnO3 (LSCMO) films grown by pulsed laser deposition technique on Si(001) substrates buffered with Bi4Ti3O12/CeO2/YSZ heteroepitaxial layers. X-ray diffraction shows cube-on-cube growth of epitaxial Bi4Ti3O12/CeO2/YSZ/Si heterostructure whereas the LSCMO layer grows in the "diagonal-on-side" manner onto the Bi4Ti3O12 (BTO) template. High resolution TEM images demonstrate sharp interfaces between the buffer layers and LSCMO film as well as rare misfit dislocations on the CeO2/YSZ interface. LSCMO film processing conditions have been optimized to get maximum temperature coefficient of resistivity TCR = 4.4%K-1 and colossal magnetoresistance (CMR) Deltarho/rho similar to 2.9%kOe(-1) @ 294K. Almost ultimate CMR performance at room temperature has been achieved due to successive improvement of c-axis orientation of layers: full widths at half-maximum (FWHM) 0.65, 0.58, 0.65, 1.13 and 0.18 degrees in LSCMO/BTO/CeO2/YSZ/Si stack, respectively. Characterization of electrical noise in CMR film yields noise equivalent temperature difference (NETD) as low as 1.2 muK/rootHz @ 30Hz and 294K.
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| 7. |
- Grishin, Alexander, et al.
(författare)
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Processing and on-wafer measurements of ferroelectric interdigitated tunable microwave capacitors
- 2004
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Ingår i: Integration Of Advanced Micro-And Nanoelectronic Devices-Critical Issues And Solutions. - : Springer Science and Business Media LLC. - 155899761X ; , s. 307-312
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Konferensbidrag (refereegranskat)abstract
- Na0.5K0.5NbO3 (NKN) and Pb(Zr0.53Ti0.47)O-3 (PZT) films have been grown by rf-magnetron sputtering and pulsed laser deposition techniques, correspondingly, on sapphire (Al2O3-0112, r-cut), YAlO3 + 1% Nd (Nd:YAlPO3-001), and quartz (Y+36degrees-cut) single crystal substrates. Interdigital capacitor (IDC) of coplanar waveguide (CPW) structures were defined by a standard lift off technique in a Au(0.5mum)/Cr(10nm) electrode electron beam evaporated on ferroelectric film surface. IDCs consisted of five pairs of fingers separated by 2 and 4 mum gap. On-wafer microwave characterization was performed using a workbench equipped with a coplanar probe station (Cascade Microtech) with G-S-G (Ground-Signal-Ground) Picoprobe, a network analyzer (Agilent Technologies E8364A) operating in 45 MHz to 40 GHz range and programmable power supply for de DUT (Device Under Test) biasing. Assumed equivalent circuit for the IDC/CPW structure contains planar capacitor under test C, the coplanar line with a complex impedance sigma and a parasitic capacitance C, between the signal and ground lines. The de-embedding technique has been employed to determine all six complex parameters C, sigma and C-p from S-parameter measurements performed for three different device structures: device, open and thru. NKN film interdigital capacitors on sapphire show superior performance in this microwave range: the frequency dispersion was as low as 18%, voltage tunability = 1 - C(40V)/C(0) (40 V, 200 kV/cm) about 14%, loss tangent similar to0.11, K-factor = tunability/tandelta from 131% @ 10 GHz: to 56% @ 40 GHz. The reliability of the de-embedding procedure is clearly proved by analysis of the frequency dependences of the parasitic capacitance and loss tangent as well as impedance of the coplanar line. Within the accuracy of experimental data and de-embedding calculations these values appear to be voltage independent: C-p similar to 70 fF, tan delta(p) changes from 0.07 @ 10 GHz to 0.15 @ 40 GHz; real and imaginary part of interconnect impedance increases with frequency from 0.16 Omega @ 10 GHz to 0.36 Omega @ 40 GHz and from 1.6 Omega @ 10 GHz to 5.84 Omega @ 40 GHz respectively.
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| 8. |
- Isheden, Christian, et al.
(författare)
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Formation of Ni mono-germanosilicide on heavily B-doped epitaxial SiGe for ultra-shallow source/drain contacts
- 2003
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Ingår i: Materials Research Society Symposium Proceedings. - 0272-9172 .- 1946-4274. ; 745, s. 117-122
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Tidskriftsartikel (refereegranskat)abstract
- The formation of Ni germanosilicides during solid-state interaction between Ni and heavily B-doped strained epitaxial Si1-xGex films with x=0.18, 0.32 and 0.37 is studied. No NiSi2 is found in these samples even after annealing at 850 degreesC, which can be compared to the formation of NiSi2 at 750 T on Si(I 00). Resistance and diffraction studies for the Si0.82Ge0.18 sample indicate that NiSi0.82Ge0.18 forms and the NiSi0.82Ge0.18/Si0.82Ge0.18 structure is stable from 400 to 700 degreesC. For the NiSi1-uGeu formed in all Si1-xGex samples, where u can be different from x, a strong film texturing is observed. When the Ge fraction is increased from 18 at.% to 32-37 at.%, the morphological stability of the film is degraded and a substantial increase in sheet resistance occurs already at 600 degreesC. The contact resistivity for the NiSi0.8Ge0.2/Si0.8Ge0.2 interface formed at 550 T is determined as 1.2x10(-7) Omegacm(2), which satisfies the ITRS contact resistivity requirement for the 70 nm technology node.
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| 9. |
- Isheden, Christian, et al.
(författare)
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Recessed and epitaxially regrown SiGe(B) source/drain junctions with Ni salicide contacts
- 2004
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Ingår i: Silicon Front-End Junction Formation-Physics And Technology. - : Springer Science and Business Media LLC. - 1558997601 ; , s. 49-54
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Konferensbidrag (refereegranskat)abstract
- Integration issues concerning recessed epitaxial SiGe(B) source/drain junctions formed by selective Si etching followed by selective epitaxial growth of in situ heavily B-doped Si1-xGex are presented. The concept is beneficial compared to conventional ion implanted junctions, since dopant activation above the solid solubility in Si can be obtained. When integrated in the PMOS process flow, the resulting Si1-xGex layer is very rough. Several possible causes for low quality epitaxy are discussed and improvements are proposed. It is suggested that the dopant type and/or concentration in the silicon substrate can have an effect on the process.
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| 10. |
- Jonsson, Mats, et al.
(författare)
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Dissolution of UO2 by one- and two-electron oxidants
- 2004
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Ingår i: Materials Research Society Symposium Proceedings. - 0272-9172 .- 1946-4274. ; 807, s. 77-82
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Tidskriftsartikel (refereegranskat)abstract
- In this work, the efficiency of one- and two-electron oxidants in oxidative dissolution Of UO2 has been investigated. This was accomplished by measuring the U(VI)-concentration in solution after exposing UO2-powder to controlled amounts of oxidants in aqueous solution. The oxidants used in this study are H2O2, IrCl62-, CO3.- and OH..H2O2 acts as a two-electron oxidant while the remaining three oxidants are one-electron oxidants. CO3.- and OH. were generated using gamma-radiolysis. The results clearly show that the dissolution yields for one-electron oxidants (per electron pair) are lower than the yields for two-electron oxidants. Furthermore, the yields for one-electron oxidants increase with increasing amount of oxidant (especially at low amounts of oxidant). The rationale for this is that U(VI) is the main soluble species which is formed directly upon two-electron oxidation. For one-electron oxidants the primary oxidation product is U(V) which can form U(VI) upon reaction with a second oxidant. The probability for a second oxidation is however low at low concentrations of oxidant.
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