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12 Oct 1998

Volume 73, Issue 15, pp. 2069-2222

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Effect of cooling rate on the precipitation of quasicrystals from the Zr–Cu–Al–Ni–Ti amorphous alloy

L. Q. Xing, J. Eckert, W. Löser, and L. Schultz

Appl. Phys. Lett. 73, 2110 (1998); http://dx.doi.org/10.1063/1.122394 (3 pages) | Cited 63 times

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The Zr57Cu20Al10Ni8Ti5 alloy solidifies into an amorphous phase upon rapid quenching or casting at low cooling rates. However, the amorphous alloys formed at different cooling rates exhibit different crystallization behavior. The slowly cooled bulk amorphous alloys prepared by copper mold casting reveal a first crystallization peak at 715 K upon heating at 0.33 K/s and crystallize via precipitation of an icosahedral quasicrystalline phase in the first crystallization step. The rapidly quenched ribbons exhibit a first crystallization peak at 720 K and crystallize by simultaneous precipitation of the quasicrystalline phase together with Zr2Cu and Zr2Ni intermetallic phases in the first stage of crystallization. It is supposed that the undercooled Zr57Cu20Al10Ni8Ti5 melt has a tendency to develop an icosahedral short-range order, which is favored by low cooling rate. As a result, the bulk amorphous alloy has a short-range order close to a quasicrystalline phase. In contrast, the structure of the ribbon is more similar to that of the melt at high temperature and the atoms are oriented more randomly. © 1998 American Institute of Physics.
Show PACS
61.44.Br Quasicrystals
81.30.Mh Solid-phase precipitation
81.30.Hd Constant-composition solid-solid phase transformations: polymorphic, massive, and order-disorder
81.05.Bx Metals, semimetals, and alloys

Electron field emission from phase pure nanotube films grown in a methane/hydrogen plasma

Olivier M. Küttel, Oliver Groening, Christoph Emmenegger, and Louis Schlapbach

Appl. Phys. Lett. 73, 2113 (1998); http://dx.doi.org/10.1063/1.122395 (3 pages) | Cited 97 times

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Phase pure nanotube films were grown on silicon substrates by a microwave plasma under conditions which normally are used for the growth of chemical vapor deposited diamond films. However, instead of using any pretreatment leading to diamond nucleation we deposited metal clusters on the silicon substrate. The resulting films contain only nanotubes and also onion-like structures. However, no other carbon allotropes like graphite or amorphous clustered material could be found. The nanotubes adhere very well to the substrates and do not need any further purification step. Electron field emission was observed at fields above 1.5 V/μm and we observed an emission site density up to 104/cm2 at 3 V/μm. Alternatively, we have grown nanotube films by the hot filament technique, which allows to uniformly cover a two inch wafer. © 1998 American Institute of Physics.
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61.46.-w Structure of nanoscale materials
79.70.+q Field emission, ionization, evaporation, and desorption
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
52.77.Bn Etching and cleaning
52.77.Dq Plasma-based ion implantation and deposition
68.55.-a Thin film structure and morphology

Deposition of (Zn, Mn)2SiO4 for plasma display panels using charged liquid cluster beam

M. Cich, K. Kim, H. Choi, and S. T. Hwang

Appl. Phys. Lett. 73, 2116 (1998); http://dx.doi.org/10.1063/1.122396 (3 pages) | Cited 32 times

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Films of manganese doped zinc silicate have been deposited using the charged liquid cluster beam technique. The deposition conditions were found to have a large impact on the morphology and photoluminescence intensity of these films. The photoluminescence intensity was maximized at a manganese content near δ=0.04 in (Zn1−δMnδ)2SiO4. No phases other than zinc silicate were detectable with manganese contents up to δ=0.08. © 1998 American Institute of Physics.
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78.55.Hx Other solid inorganic materials
78.66.Nk Insulators
81.15.Jj Ion and electron beam-assisted deposition; ion plating
68.55.-a Thin film structure and morphology

Field emission from aligned high-density graphitic nanofibers

Yan Chen, Sushil Patel, Yagu Ye, David T. Shaw, and Liping Guo

Appl. Phys. Lett. 73, 2119 (1998); http://dx.doi.org/10.1063/1.122397 (3 pages) | Cited 76 times

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Field emission data from aligned graphitic nanofibers have been obtained. The aligned nanofibers are 50–100 nm in diameter and 6–10 μm in length, with a density of 109–1010/cm2. The fibers were grown on polycrystalline nickel substrate by plasma-assisted hot filament chemical vapor deposition using a gas mixture of nitrogen and acetylene. The onset of emission current in microampere level was detected at about 1.8 V/μm with an emission area of 1 mm2. The Fowler–Nordheim model was used to analyze the data obtained. The field emission current required for flat panel display can be easily achieved at 2.5 V/μm. © 1998 American Institute of Physics.
Show PACS
79.70.+q Field emission, ionization, evaporation, and desorption
61.46.-w Structure of nanoscale materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.07.-b Nanoscale materials and structures: fabrication and characterization
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