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Publikācija: The Synthesis and Characterization of Nickel and Cobalt Ferrite Nanopowders Obtained by Different Methods

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Nosaukums oriģinālvalodā The Synthesis and Characterization of Nickel and Cobalt Ferrite Nanopowders Obtained by Different Methods
Pētniecības nozare 2. Inženierzinātnes un tehnoloģijas
Pētniecības apakšnozare 2.5. Materiālzinātne
Autori Ilmārs Zālīte
Gundega Heidemane
Leonora Kuznetsova
Māris Kodols
Jānis Grabis
Mihail Maiorov
Atslēgas vārdi Ni and Co ferrites, nanopowders, plasma chemical synthesis, sol-gel self-combustion method, co-precipitation technology, properties
Anotācija The materials of ferrites especially nickel and cobalt ferrites are popular with their unique mechanical and magnetic properties. Currently the involvement of ferrite nanomaterials and nanopowders in life sciences, biochemical processes (magnetic liquids, hyperthermia etc.), in chemical catalysis and coating technologies with polymers are very outstanding. In this research the nickel and cobalt ferrite nanopowders prepared by the chemical sol-gel self-combustion method, by co-precipitation technology, combined with the hydrothermal synthesis method and by the high frequency plasma chemical synthesis and their mechanical and magnetic properties has been studied. In sol-gel method the disperse Co and Ni ferrites are obtained from the appropriate metal nitrate salt solutions of stoichiometric ratio. Glycine (Gly) is used as the self-combustion agent with molar ratio Me/Gly = 1:0,8 and Gly/Nitr. = 1:4. By the hydrothermal synthesis method the precursor was prepared by hydrolysis of FeCl3 and by co-precipitation of Fe and Co or Ni hydroxides. Then they obtained mixture of hydroxides was treated by hydrothermal way at different temperatures. The high frequency plasma synthesis of the nanosized materials is based on vaporization of metal oxides in the plasma and very fast cooling of the vapor, resulting in nanosized ferrite particles. Nanopowders synthesized in the high frequency plasma are of specific surface area 28 – 30 m2/g (the average particle size 38 – 40 nm, crystallite size ~40 nm). The ferrite nanopowders obtained by sol-gel self-combustion and hydrothermal methods have the specific surface area of 35 – 40 m2/g (average particle size 30 - 35 nm, crystallite size ~20 nm) and 45 – 60 m2/g (average particle size 20 - 25 nm, crystallite size ~ 12 - 20 nm), respectively. The magnetic properties of nanopowders obtained by the high frequency plasma synthesis are next: for nickel ferrite saturation magnetization MS=44,2 emu/g, remanent magnetization Mr=10,0 emu/g, coercivity Hc=74 Oe, for cobalt ferrite MS=75,4 emu/g, Mr=32,0 emu/g, Hc=780 Oe. The magnetic saturation values of these samples are very close to the values of the standard bulk material. However the magnetic properties of the samples obtained with sol-gel self-combustion and hydrothermal methods have for nickel ferrite MS=29,0 emu/g, Mr=6,0 emu/g, Hc=140 Oe and MS=30-40 emu/g, Mr=2,7 emu/g, Hc=20-35 Oe, but for cobalt ferrite - MS=53,4 emu/g, Mr=20,3 emu/g, Hc=1170 Oe and MS= 50-60 emu/g, Mr=10-18 emu/g, Hc=500-650 Oe, respectively. Also the results on properties of compacted materials from the obtained nanopowders are reviewed.
Atsauce Zālīte, I., Heidemane, G., Kuznetsova, L., Kodols, M., Grabis, J., Maiorov, M. The Synthesis and Characterization of Nickel and Cobalt Ferrite Nanopowders Obtained by Different Methods. No: BaltSilica 2016: The 7th International Conference on Silicate Materials, Lietuva, Kaunas, 26.-27. maijs, 2016. Kaunas: Kaunas University of Technology, 2016, 67.-67.lpp. ISSN 2243-6057.
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