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  • 1
    Electronic Resource
    Electronic Resource
    Magnetic properties of Nd–Fe–Co(Cu)–Al–B amorphous alloys prepared by nonequilibrium techniques (2002)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 91 (2002), S. 3764-3768 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The amorphous alloys Nd40Fe40Co5Al8B7, Nd57Fe20Co5Al10B8, and Nd57Fe20Cu5Al10B8 were prepared by copper mold casting, melt spinning, and mechanical alloying. Despite their similar x-ray diffraction patterns, samples display different magnetic and thermal behavior correlated with the method of preparation. The fully amorphous melt-spun ribbons exhibit relatively soft magnetic properties with coercivities (approximate)40 kA/m at room temperature and a Curie temperature (TC)(approximate)474 K. Apparently only the mold-cast cylinders of 3 mm diameter show hard magnetic behavior with a coercivity in the range of 258–270 kA/m (depending on composition) and have approximately the same TC as that of the melt-spun ribbons. An additional magnetic transition at 585 K due to the presence of Nd2Fe14B phase in the case of Nd40Fe40Co5Al8B7 cast rod has been observed. Heat treatment above crystallization temperature in as-cast Nd57Fe20Co5Al10B8 and Nd57Fe20Cu5Al10B8 samples destroys the hard magnetic properties. In contrast, mechanically alloyed amorphous samples are soft magnetic with maximum coercivity up to 11 kA/m but show an entirely different TC(approximate)680–740 K, which is rather characteristic of an Fe solid solution. The magnetic properties are discussed in terms of different local atomic environment and cluster sizes in amorphous samples prepared by different methods. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1448884
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  • 2
    Electronic Resource
    Electronic Resource
    Growth and electrical transport of germanium nanowires (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 5747-5751 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Single crystalline germanium nanowires have been synthesized from gold nanoparticles based on a vapor–liquid–solid growth mechanism. Germanium powder was evaporated at 950 °C, and deposited onto gold nanoparticles at 500 °C using argon as a carrier gas. The diameter of the germanium nanowires ranged from 20 to 180 nm when gold thin films were utilized as the substrate, while the nanowires grown from 10 nm Au particles showed a narrower diameter distribution centered at 28 nm. The growth direction of germanium nanowires is along the [111] direction, determined by high resolution transmission electron microscopy. Transport measurements on individual Ge nanowires indicate that the wires are heavily doped during growth and that transport data can be explained by the thermal fluctuation tunneling conduction model. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1413495
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  • 3
    Electronic Resource
    Electronic Resource
    Atomic ordering and magnetic properties in Nd57Fe20B8Co5Al10 solids (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 3565-3569 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Nd57Fe20B8Co5Al10 bulk cylinders and ribbons were quenched from the melt at different cooling rates using copper mold casting and melt spinning, respectively. Both the melt-spun ribbons and the cast cylinders display x-ray diffraction patterns without obvious crystalline peaks. However, the ribbons show soft magnetic properties, the cylinders are hard magnetic, and the crystallized alloys are not ferromagnetic at all. On the other hand, the cylinders show different exothermic transformation behavior than the ribbons upon heating to elevated temperatures. While the ribbons are regarded as amorphous, the structure of the cylinders prepared at slower cooling rate is considered to consist of metastable ordered clusters. This structure forms in the undercooled melt most likely due to intensive generation of ordered nuclei and slow growth kinetics. The magnetic coherence length, which is equivalent to the dimension of the ordered clusters, may be larger than the exchange length. Therefore, the cylinders shows much larger coercivity than the ribbons. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1288697
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  • 4
    Electronic Resource
    Electronic Resource
    Thermal expansion coefficients of low-k dielectric films from Fourier analysis of x-ray reflectivity (2000)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 88 (2000), S. 691-695 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We determine the thermal expansion coefficient of a fluorinated poly(arylene ether) low-k dielectric film using Fourier analysis of x-ray reflectivity data. The approach is similar to that used in Fourier analysis of x-ray absorption fine structure. The analysis compares two similar samples, or the same sample as an external parameter is varied, and determines the change in film thickness. The analysis process is very accurate and depends on no assumed model. We determine a thermal expansion coefficient of 55±9×10−6 K−1 using this approach. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.373722
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  • 5
    Electronic Resource
    Electronic Resource
    Temperature-induced change from p to n conduction in metallofullerene nanotube peapods (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 79 (2001), S. 3845-3847 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Metallofullerene nanotube peapods were prepared by introducing Dy@C82 into the interior space of single-walled carbon nanotubes. Transport measurements show that the Dy@C82 molecules function as electron donors and transfer charge to the carbon nanotube host. The amount of charge transferred varies with the temperature. At room temperature, the doped nanotube shows p-type behavior as seen from the response to a back gate. As the temperature decreases, the conductance becomes n type and at T〈215 K metallic behavior is observed, indicating the degenerate state by doping. Below about 75 K, single-electron charging phenomena dominate the transport and show irregular Coulomb blockade oscillation, implying that the insertion of Dy@C82 splits the tube into a series of several quantum dots. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1415770
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  • 6
    Electronic Resource
    Electronic Resource
    Kinetics of the glass-transition and crystallization process of Fe72−xNbxAl5Ga2P11C6B4 (x=0, 2) metallic glasses (2001)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 78 (2001), S. 2145-2147 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The kinetics of the glass-transition and the crystallization process of multicomponent ferromagnetic Fe72−xNbxAl5Ga2P11C6B4 (x=0, 2) metallic glasses have been investigated by constant-rate heating differential scanning calorimetry at different heating rates. The glass-transition temperature Tg and the crystallization peak temperature Tp shift to higher temperatures with increasing heating rate. The apparent activation energy and the frequency factor are evaluated by the Kissinger method, and the rate constant of the crystallization process is estimated by an Arrhenius law. The kinetics of the glass-transition process have been analyzed in terms of a Vogel–Fulcher–Tammann equation describing the heating rate dependence of the glass-transition temperature. The effect of the niobium addition on the glass-forming ability has been investigated with respect to the glass-transition and crystallization kinetics, revealing that substitution of Nb for Fe does not improve the glass-forming ability and it lowers the thermal stability of the material. © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1361099
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  • 7
    Electronic Resource
    Electronic Resource
    Microstructured gold/Langmuir–Blodgett film/gold tunneling junctions (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 66 (1995), S. 3331-3333 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We prepared symmetric sandwich structures of the sequence gold/Langmuir–Blodgett film/gold by employing a novel evaporation technique. As molecular systems, we used an octasubstituted palladiumphthalocyanine and a perylene-3,4,9,10-tetracarboxyldiimide derivative. Electronic transport measurements show a tunneling characteristic which arises from a direct tunneling process through molecular states. The current/voltage curves are symmetric for positive and negative bias proving the identical electronic behavior of the two organic/inorganic interfaces at the top and bottom electrode. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.113747
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  • 8
    Electronic Resource
    Electronic Resource
    Magnetic properties of cast Nd60−xFe20Al10Co10Cux alloys (1999)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 75 (1999), S. 2984-2986 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The effect of Cu on the magnetic properties of slowly cooled Nd60−xFe20Al10Co10Cux (0≤x≤10) bulk amorphous alloys has been studied by room-temperature magnetic measurements. Ferromagnetic bulk amorphous Nd60Fe20Al10Co10 cylinders of 3 mm diameter and 50 mm in length with a coercivity of 298 kA m−1 were obtained by copper mold casting. The addition of 1 at. % Cu into the Nd60Fe20Al10Co10 alloy causes an increase in coercivity to 321 kA m−1. Further addition of Cu by replacing neodymium, however, results in an abrupt decrease in coercivity to 41 kA m−1 for alloys with x=10 due to the precipitation of a Fe-rich magnetically soft Nd(Fe, Co, Al)2 phase. The improvement of the hard magnetic properties by the addition of 1 at. % Cu for the cast Nd60Fe20Al10Co10 based bulk amorphous alloys may be attributed to an enhanced clustering of Nd–(Fe, Co) pairs in the amorphous alloys. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.125209
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  • 9
    Electronic Resource
    Electronic Resource
    Effect of preparation mode on Class II resin composite repair (2003)
    Oxford, UK : Blackwell Science Ltd
    Journal of oral rehabilitation 30 (2003), S. 0 
    Details
    ISSN: 1365-2842
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: summary  Complete removal of failed posterior resin composite fillings is time-expensive and involves the risk of removing sound tooth substance. In any case of failure within the composite material, intra-oral repair would be favourable. This in vitro study was conducted to examine the effect of different preparation and bonding modes on integrity of repaired restorations. Forty-eight direct Class II resin composite restorations (Syntac Classic®/Tetric Ceram®) were placed in extracted human third molars. The specimens were stored for 365 days and then replaced partially by removing the central part of the proximal box with all margins located in composite. The partial repairs were placed with the same materials after pre-treatment with a silicon carbide bur and Syntac Classic (n = 8). Preparation modes have been (i) box-only parallel, (ii) box-only with undercuts, (iii) box with undercuts and additional occlusal retention. The repairs were performed either with (i) Tetric Ceram® or with (ii) Tetric Flow® as thin lining covered with Tetric Ceram®. Before and after thermomechanical loading (100 000 cycles of 50 N and 2500 cycles between +5 and +55 °C in an artificial mouth), marginal quality between aged and freshly applied composite was evaluated by SEM at ×200 magnification and microleakage was observed by light microscopy at ×50 magnification. Box-only preparations exhibited a better fatigue resistance than preparations with additional occlusal retention. This observation was independent from the presence of undercuts (P 〈 0·05). An intermediary layer of flowable resin composite tended to result in better marginal quality, however, not being statistically significant.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2842.2003.01031.x
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  • 10
    Electronic Resource
    Electronic Resource
    Gold cluster formation at the interface of a gold/Langmuir-Blodgett film/gold microsandwich resulting in Coulomb charging phenomena (1999)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 3374-3376 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Structural analysis of the cross section of gold/Langmuir-Blodgett (LB) polymer film/gold sandwich structures was performed using transmission electron microscopy (TEM), and the obtained results were complemented by electron transport investigations of the sandwich structures. The polymer film consisted of four to ten LB monolayers of a nonconducting polymer. TEM analysis of the sandwich cross section revealed a number of gold particles, 2–5 nm in size, formed during the fabrication process within the LB film close to the top electrode. Low temperature dc-transport measurements showed current-voltage (I-V) characteristics with equidistant steps that are not expected if the polymer film is thought to form a single laterally extended tunneling barrier between the metal electrodes. This feature can be understood, however, on the basis of the Coulomb blockade model applied to cluster-like metallic inclusions acting as an island separated from both Au electrodes by tunneling barriers. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.369691
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