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- Svechnikov, S., et al.
(författare)
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Spiral antenna nbn hot-electron bolometer mixer at submm requencies
- 1997
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Ingår i: IEEE Transactions on Applied Superconductivity. - : Institute of Electrical and Electronics Engineers (IEEE). - 1558-2515 .- 1051-8223. ; 7:2, s. 3395-3398
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Tidskriftsartikel (refereegranskat)abstract
- We have studied the phonon-cooled hot-electron bolometer (HEB) as a quasioptical mixer based on a spiral antenna designed for the 0.3-1 THz frequency band and fabricated on sapphire and high resistivity silicon substrates. HEB devices were produced from superconducting 3.5-5 nm thick NbN films with a critical temperature 10-12 K and a critical current density of approximately 10/sup 7/ A/cm/sup 2/ at 4.2 K. For these devices we reached a DSB receiver noise temperature below 1500 K, a total conversion loss of L/sub t/=16 dB in the 500-700 GHz frequency range, an IF bandwidth of 3-4 GHz and an optimal LO absorbed power of /spl sime/4 /spl mu/W. We experimentally analyzed various contributions to the conversion loss and obtained an RF coupling factor of about 5 dB, internal mixer loss of 10 dB and IF mismatch of 1 dB.
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- Yao, Yiming, 1957, et al.
(författare)
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Adhesion between nanoparticles
- 1999
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Ingår i: Nanostructured Materials. ; 12:5-8, s. 661-664
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- A study of the contact and adhesion between panicles with clean surfaces (free from oxide and other contamination) is important but increasingly more difficult to perform as the particle size is reduced to a nanoscale. A reproducible way of finding such contacts between a large number of nanoparticles has been developed. Cobalt particles within the size range 5–200 nm have been obtained by ageing a solution-treated Cu-2Co (w/o) alloy at 600–800 °C, followed by the carbon film extraction technique. The dipole adhesion stress field was clearly observed in TEM. Convergent beam electron diffraction (CBED) proved that the free panicles were likely to contact with a common interface, and they often orientated in the same direction. This work establishes a solid experimental base for computational image matching of the adhesion properties of nanoparticles.
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- Yao, Yiming, 1957, et al.
(författare)
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Electron diffraction contrast from contacting nano-particles
- 1999
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Ingår i: 1999 Annual Scientific Meeting of ESF-NANO Programme “Vapor-Phase Synthesis and Processing of Nanoparticles Materials (NANO)”, Duisburg, Germany. ; , s. 27-31
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Konferensbidrag (refereegranskat)
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