I. V. Tananaev Institute of Chemistry and Technology of Rare Elements and Mineral Raw Materials, Kola Scientific Centre, Russian Academy of Sciences

I. G. Kolesnikova, Senior Researcher, e-mail: koles_ig@chemy.kolasc.net.ru
V. G. Korotkov, Leading Technologist
B. M. Freydin, Head of Laboratory of Powder Metallurgy, Senior Researcher
Yu. V. Kuzmich, Senior Researcher
L. A. Mayorov, Post-Graduate Student

The paper deals with the production of magnetic nanocomposites of the cobalt—zeolite (erionite, NaX) system by using chemical precipitation followed by hydrogen reduction of cobalt compounds in zeolite pores. It has been shown that hydrogen reduction in the temperature range of 250–350 ^oC promotes the formation of a cobalt phase with hexagonal ordering on zeolite; whereas at temperatures higher than 350 ^oC, a cubic cobalt phase is formed. It has been determined that at temperatures lower than 250 ^oC the metal phase is predominantly formed in the pores, while at 400–600 ^oC it is present both in the pores and on the surface of zeolite particles. The process is not accompanied by changing of the matrix crystalline structure. Subsequent destruction of the latter at temperatures higher than 600 ^oC resulting in increase of particle sizes in the metal phase is due to amorphization characteristic of most of zeolites in the given temperature range. The method allows to introduce into zeolite pores up to 10% cobalt. We have studied the dispersibility of the metal phase and magnetic characteristics of powder systems depending on conditions of their formation. The coercive force of cobalt on NaX zeolite was found to be higher than that on erinionite. The resulting nano-systems are characterized by high magnetic properties. The maximal coercive force of the Co—NaX systems is 70 kА/m, remanent magnetic induction — 15 А·m²/kg, saturation magnetization — about 40 А·m²/kg. These parameters satisfy the requirements to the media of magnetic recording of information.

1. Umanskiy Ya. S., Skakov Yu. A., Ivanov A. N. et al. Kristallografiya, rentgenografiya i elektronnaya mikroskopiya (Crystallographics, X-ray radiography and electronic microscopy). Moscow, 1982. 631 p.
2. Gorelik S. S., Skakov Yu. A., Rastorguev L. N. Rentgenograficheskiy i elektronno-opticheskiy analiz (X-ray radiography and electron-optical analysis). Moscow, 2002. 328 p.

3. Gusev A. I. Nanomaterialy, nanostruktury, nanotekhnologii (Nanomaterials, nanostructures, nanotechnologies). Moscow, 2005. 416 p.
4. Kolesnikova I. G., Freydin B. M., Kuzmich Yu. V., Serba V. I. Metally — Metals. 2009. No. 4. pp. 92–95.
5. Brek D. Tseolitovye molekulyarnye sita (Zeolitic molecular sieves). Moscow, 1976. 781 p.
6. Zhdanov S. P., Khvoshchev S. S., Samulevich N. N. Sinteticheskie tseolity (Synthetic zeolites). Moscow, 1981. 261 p.
7. Rabo Dzh. Khimiya tseolitov i kataliz na tseolitakh (Chemistry of zeolites and catalysis with zeolites). Moscow, 1980. Book. 1. 506 p.