|
ИСТИНА |
Войти в систему Регистрация |
ФНКЦ РР |
||
Canted spin structure and the first order magnetic transition in CoFe2O4 nanoparticles coated by amorphous silicaстатья
- Авторы: Lyubutin I.S., Starchikov S.S., Gervits N.E., Korotkov N.Yu, Dmitrieva T.V., Lin Chun-Rong, Tseng Yaw-Teng, Shih Kun-Yauh, Lee Jiann-Shing, Wang Cheng-Chien
- Журнал: Journal of Magnetism and Magnetic Materials
- Год издания: 2016
- Издательство: Elsevier BV
- Местоположение издательства: Netherlands
- DOI: 10.1016/j.jmmm.2016.01.090
- Аннотация: The functional polymer (PMA-co-MAA) latex microspheres were used as a core template to prepare magnetic hollow spheres consisting of CoFe2O4 / SiO2 composites. The spinel type crystal structure of CoFe2O4 ferrite is formed under annealing, whereas the polymer cores are completely removed after annealing at 450°C. Magnetic and Mössbauer spectroscopy measurements reveal very interesting magnetic properties of the CoFe2O4 / SiO2 hollow spheres strongly dependent on the particle size which can be tuned by the annealing temperature. In the ground state of low temperatures, the CoFe2O4 nanoparticles are in antiferromagnetic state due to the canted magnetic structure. Under heating in the applied field, the magnetic structure gradually transforms from canted to collinear, which increases the magnetization. The Mössbauer data revealed that the small size CoFe2O4 / SiO2 particles (2.2 – 4.3 nm) do not show superparamagnetic behavior but transit from the magnetic to the paramagnetic state by a jump-like magnetic transition of the first order This effect is a specific property of the magnetic nanoparticles isolated by inert material, and can be initiated by internal pressure creating at the particle surface. The suggested method of synthesis can be modified with various bio-ligands on the silane surface, and such materials can find many applications in diagnostics and bioseparation.
- Добавил в систему: Гервиц Наталья Евгеньевна