K. A. Bolshakov Chair of Chemistry and Technology of Rare and Scattered Elements, Nanosize and Composite Materials, Moscow Technological University (Institute of Fine Chemical Technologies), Moscow, Russia:

D. V. Drobot, Head of a Chair, e-mail: dvdrobot@mail.ru
K. A. Smirnova, Leading Engineer, Post-Graduate Student
E. S. Kulikova, Head of Laboratory, Post-Graduate Student
V. Yu. Musatova, Post-Graduate Student

Our investigations, carried out in the past decade, show the progress in the synthesis of functional materials (luminophores and magnetic materials). Their results are given in this paper. Oxides L-Та₂O₅ (lattice parameters: a = 0.619484(18) nm, b = 4.02547(9) nm, с = 0.389060(7) nm) and T-Nb2O5 (lattice parameters: a = 0.62029(9) nm, b = 2.9205(4) nm, c = 0.39235(4) nm) were obtained by Supercritical AntiSolvent (SAS) method. Supercritical СО2 is the ideal solvent: pressure release leads to the gas evaporation without the product contamination. Pressure and temperature of the critical point are 7.38 MPa and 31 °C. Specific surface area of Nb₂O₅ is 259.5 m²/g, which is much higher than the one of technical product (4.4 m²/g). At the same time, specific surface area of Ta₂O₅ is 435.9 m²/g, which is by 400 times higher than the one of technical product (1.3 m²/g). To obtain the metallopolymer cobalt (II) and nickel (II) nanocomposites acidic carboxylates of these metals of unsaturated dicarboxylic were synthesized and characterized by thermal analysis and IR spectroccopy. Thermolysis of synthesized carboxylates was carried out, and obtained nanocomposites were investigated by transmission and scanning electron microscopy and X-ray diffraction. The synthesized metallopolymer Co (II) and Ni (II) nanocomposites, obtained as a result of thermal carboxylates decomposition in argon atmosphere, are black powders consisting of two structural elements: nanoparticles Co₃O₄/CoO or NiO/ß-Ni in polymeric shell are implanted in organic polymeric matrix (in accordance with the X-ray diffraction data).
This scientific work was carried out with the financial support of the Russian Foundation for Basic Research (Projects No. 13-03-00342, 16-03-00148, 15-03-04436).

1. Korovin S. S., Drobot D. V., Fedorov P. I. Redkie i rasseyannye elementy. Khimiya i tekhnologiya (Rare and scattered elements. Chemistry and technology). In three volumes. Tutorial for universities. Under the editorship of S. S. Korovin. Moscow : MISiS, 1999. Book 2. 464 p.
2. Bach D. EELS investigations of stoivhiometric niobium oxides and niobium-based capacitors : Dissertation des akademischen Grades eines Doctors der Naturwissenschaften. Karlsruhe, Germany : Universität Karlsruhe, 2009. S. 204.
3. Nikishina E. E., Drobot D. V., Lebedeva E. N. Khimiya i tekhnologiya niobiya i tantala. Prostye i slozhnye oksidy (Chemistry and technology of niobium and tantalum. Simple and complex oxides). Moscow : Publishing House of Moscow Institute of Fine Chemical Technologies, 2013. 178 p.
4. Markku Rantakylä. Particle production by supercritical antisolvent processing techniques : Dissertation for the degree of Doctor of Technology. Espoo, Finland : Helsinki University of Technology, 2004. 146 p.
5. Rao K. N. V. Supercritical Fluid Extraction (SFE) — An overview. Asian Journal of Pharmaceutical Sciences. 2012. Vol. 2, No. 3. pp. 112–120.
6. Turova N. Ya., Turevskaya E. P., Kessler V. G., Yanovskaya M. I. The che mistry of metal alkoxides. Dordrecht, Netherlands : Kluwer Academic Publishers, 2001. 562 p.
7. Yanovskiy A. I., Turova N. Ya., Korolev A. V. et al. Oksoalkogolyaty tantala (V) (Tantalum (V) oxoalcoholates). Izvestiya AN SSSR. Seriya khimicheskaya = News of USSR Academy of Sciences. Chemical series. 1996. No. 1. pp. 125–131.
8. Smirnova K. A., Fomichev V. V., Drobot D. V., Nikishina E. E. Poluchenie nanorazmernykh pentaoksidov niobiya i tantala metodom sverkhkriticheskogo flyuidnogo antisolventnogo osazhdeniya (Obtaining nanosized niobium and tantalum pentoxides by using supercritical antisolvent fluid technology). Tonkie khimicheskie tekhnologii = Fine Chemical Technologies. 2015. Vol. 10, No. 1. pp. 76–82.
9. Nikishina E. E., Lebedeva E. N., Prokudina N. A., Drobot D. V. Upravlyaemyy sintez malovodnykh gidroksidov niobiya i tantala, fazovyy sostav i obemnye svoystva produktov ikh termoliza (Controlled synthesis of low-hydrated niobium and tantalum hydroxides: Phase composition and bulk properties of their thermolysis products). Zhurnal neorganicheskoy khimii = Russian Journal of Inorganic Chemistry. 2015. Vol. 60, No. 4. pp. 487–495.
10. Rozenberg A. S., Dzhardimalieva G. I., Pomogaylo A. D. Formirovanie nanorazmernykh chastits pri tverdofaznykh termicheskikh prevrashcheniyakh karboksilatov metallov (Formation of nanosized particles with solid thermal transformations of metal carboxilates). Doklady Akademii Nauk = Reports of Academy of Sciences. 1997. Vol. 356, No. 1. pp. 66–69.
11. Gubin S. P., Koksharov Yu. A., Khomutov G. B., Yurkov G. Yu. Magnitnye nanochastitsy: metody polucheniya, stroenie, svoystva (Magnetic nanoparticles: preparation, structure and properties). Uspekhi khimii = Russian Chemical Reviews. 2005. Vol. 74, No. 6. pp. 539–574.
12. Sellmyer D. J., Yu M., Kirby R. D. Nanostructured magnetic films for extremely high density recording. Nanostructured Materials. 1999. Vol. 12, No. 58. pp. 1021–1026.
13. Mornet S., Vasseur S., Grasset F., Duguet E. Magnetic nanoparticle design for medical diagnosis and therapy. Materials Chemistry. 2004. Vol. 14. pp. 2161–2175.
14. Khlebnikov V. K., Vishvasrao Kh. M., Sokolskaya M. A. et al. Vodorastvorimye magnitnye nanochastitsy kak potentsialnye agenty dlya magnitnoy gipertermii (Water-soluble magnetic nanoparticles as a potential agents for magnetic hyperthermia). Vestnik MITKhT = News of the Bulletin of Moscow Institute of Fine Chemical Technologies. 2012. Vol. 7, No. 1. pp. 64–68.
15. Pomogaylo A. D., Rozenberg A. S., Dzhardimalieva G. I. Termoliz metallopolimerov i ikh predshestvennikov kak metod polucheniya nanokompozitov (Thermolysis of metallopolymers and their precursors as a method for the preparation of nanocomposites). Uspekhi khimii = Russian Chemical Reviews. 2011. Vol. 80, No. 3. pp. 272–307.
16. Pomogaylo A. D., Dzhardimalieva G. I. Metallopolimernye gibridnye nanokompozity (Metal-polymeric hybride nanocomposites). Moscow : Nauka, 2015. 494 p.
17. Semenov S. A., Drobot D. V., Musatova V. Yu. et al. Sintez i termicheskie prevrashcheniya nenasyshchennykh dikarboksilatov kobalta (II) — prekursorov metallopolimernykh nanokompozitov (Synthesis and thermal conversions of unsaturated cobalt (II) dicarboxylates as precursors of metallopolymer nanocomposites). Zhurnal neorganicheskoy khimii = Russian Journal of Inorganic Chemistry. 2015. Vol. 60, No. 8. pp. 991–1000.
18. Musatova V. Yu., Semenov S. A., Drobot D. V. et al. Sintez i termicheskie prevrashcheniya nenasyshchennykh dikarboksilatov nikelya (II) — prekursorov metallopolimernykh nanokompozitov (Synthesis and thermal conversions of unsaturated nickel (II) dicarboxylates as precursors of metallopolymer nanocomposites). Zhurnal neorganicheskoy khimii = Russian Journal of Inorganic Chemistry. 2016. Vol. 61, No. 9. pp. 1168–1181.
19. Morgunov R. B., Dmitriev A. I., Dzhardimalieva G. I. et al. Ferromagnitnyy rezonans kobaltovykh nanochastits v polimernoy obolochke (Ferromagnetic resonance of cobalt nanoparticles in the polymer shell). Fizika tverdogo tela = Physics of the Solid State. 2007. Vol. 49, No. 8. pp. 1436– 1441.
20. O'Grady K., Laidler H. The limits to magnetic recording — media considerations. Journal of Magnetism and Magnetic Materials. 1999. Vol. 200. pp. 616–633.
21. Martin J. I., Nogues J., Liu K., Schuller I. K. Ordered magnetic nanostructures: fabrication and properties. Journal of Magnetism and Magnetic Materials. 2003. Vol. 256. pp. 449–501.
22. Chen C., Kitakami O., Shimada Y. Particle size effects and surface anisotropy in Fe-based granular films. Journal of Applied Physics. 1998. Vol. 84, No. 4. pp. 2184–2188.
23. Bagmut A. G., Shipkova I. G., Zhuchkov V. A. Struktura i magnitnoe sostoyanie plenok, osazhdennykh lazernoy ablyatsiey sostavnykh misheney nikelya i palladiya (Structure and magnetic state of the films, precipitated by laser ablation of composite targets of nickel and palladium). Zhurnal tekhnicheskoy fiziki = Technical Physics. The Russian Journal of Applied Physics. 2011. Vol. 81, No. 4. pp. 102–110.
24. Yoon Tae Jeon, Je Yong Moon et al. Comparison of the Magnetic Properties of Metastable Hexagonal Close-Packed Ni Nanoparticles with Those of the Stable Face-Centered Cubic Ni Nanoparticles. The Journal of Physical Chemistry B. 2006. Vol. 110, No. 3. pp. 1187–1191.
25. Zhigalov V. S., Frolov G. I., Myagkov V. G. et al. Issledovanie nanokristallicheskikh plenok nikelya, osazhdennykh v atmosfere azota (Investigation of nanocrystalline films of nickel, precipitated in nytrogen atmosphere). Zhurnal tekhnicheskoy fiziki = Technical Physics. The Russian Journal of Applied Physics. 1998. Vol. 68, No. 9. pp. 136–138.
26. Mahendraprabhu K., Elumalai P. Influence of citric acid on formation of Ni/NiO nanocomposite by sol-gel synthesis. Journal of Sol-Gel Science and Technology. 2015. Vol. 73. pp. 428–433.
27. Proenca M. P., Sousa C. T., Pereira A. M. et al. Size and surface effects on the magnetic properties of NiO-nanoparticles. Physical Chemistry Chemical Physics. 2011. Vol. 13. pp. 9561–9567.
28. Thota S., Kumar J. Sol-gel synthesis and anomalous magnetic behaviour of NiO nanoparticles. Journal of Physics and Chemistry of Solids. 2007. Vol. 68, No. 10. pp. 1951–1964.