Structural and magnetic properties of Ni nanowires grown in mesoporous silicon templates
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- 作者：A.L. Dolgiy ; S.V. Redko ; I. Komissarov ; V.P. Bondarenko ; K.I. Yanushkevich ; S.L. Prischepa
- 关键词：Mesoporous silicon ; Electrochemical deposition ; Magnetic nanowires ; Magnetic nanocomposite ; Specific magnetization ; Curie temperature
- 刊名：Thin Solid Films
- 出版年：2013
- 出版时间：30 September, 2013
- 年：2013
- 卷：543
- 期：Complete
- 页码：133-137
- 全文大小：877 K
文摘
Structural and magnetic properties of Ni nanowires electrochemically deposited into pores of mesoporous silicon template under the stationary galvanostatic regime have been investigated. Samples have been exhaustively studied by using scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy and specific magnetization measurements. SEM analysis revealed the formation of porous silicon/nickel nanocomposite at the initial stages of Ni deposition with the characteristic dimension of Ni nanoparticles in the range of 40-60 nm. After 60 min of deposition Ni continuous nanowires of 10 ¦Ìm length have been formed. XRD analysis confirmed the polycrystalline structure of Ni in the mesoporous silicon template with the preferential orientation along [111] axis. Also some amount of silicide Ni2Si was formed, which diffraction peak at 2¦¨ ¡Ö 33¡ã was especially pronounced for low deposition times. The possible mechanism of nickel silicide formation during the electrochemical process has been discussed. It was supposed that, the presence of amorphous silicon on pore walls facilitates the diffusion of Ni inside silicon matrix with subsequent nickel silicide formation without heating. The idea has been confirmed by the fact that on crystalline silicon the formation of nickel silicide was not observed.
The magnetic properties have been investigated by studying the temperature dependence (77 K-700 K) of the specific magnetization ¦Ò. The measured ¦Ò values were lower with respect to that of bulk Ni. The effect has been explained by the influence of uncontrolled formation of nickel silicide, which causes, after heating, larger irreversibility of ¦Ò(T) curves for samples with less deposition time. The obtained ¦Ò(T) dependencies allowed us to determine the Curie temperature, TC, which for low deposition times of Ni was lower (575 K) with respect to the bulk Ni (630 K). This is caused by the influence of dimensional effects on TC value.