کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1419621 | 986052 | 2006 | 5 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Magnetic properties of CNX whiskers Magnetic properties of CNX whiskers](/preview/png/1419621.png)
Carbon–nitrogen whiskers have been prepared by pyrolysis of 1,2-diaminopropane at 950 °C or of allylamine at 900 °C followed by quenching. They are scrolls of carbon film typically 250 nm thick and up to 1 mm long with about five layers in a structure like a “cigare russe” or “brandy snap”, about 50 μm in diameter. Approximately 8 wt% of nitrogen is incorporated into the carbon films, which are practically amorphous, exhibiting a broad diffraction peak at d = 0.34 nm. The whiskers are on the border of metallic conductivity with a resistivity of about 10−6 Ωm, and they may show either a positive or a negative temperature coefficient of resistance. The pyrolysis produces either whiskers, soot or both. Magnetization measurements of the whiskers made from 1,2-diaminopropane reveal a large diamagnetic susceptibility of χ = −170 × 10−9 m3 kg−1 and a small ferromagnetic component of unknown origin with σS of up to 0.2 A m2 kg−1, whereas the soot shows a purely diamagnetic signal, with χ ≈ −40 × 10−9 m3 kg−1.
Journal: Carbon - Volume 44, Issue 15, December 2006, Pages 3213–3217