| Autor: |
Saukhimov, A., Hobosyan, M., Dannangoda, G., Zhumabekova, N., Almanov, G., Kumekov, S., Martirosyan, K. |
| Zdroj: |
International Journal of Self-Propagating High-Temperature Synthesis; Apr2015, Vol. 24 Issue 2, p63-71, 9p |
| Abstrakt: |
Rare earth ferrites exhibit remarkable magnetodielectric properties that are sensitive to the crystallite size. There is a major challenge to produce these materials in nanoscale due to particles conglomeration during the ferrite nucleation and synthesis. In this paper we report the fabrication of nanostructured particles of rare earth ferrites in the Me-Fe-O system (Me = Y, La, Ce, and Sm) by Solution-Combustion Synthesis (SCS). The yttrium, lanthanum, cerium, samarium and iron nitrates were used as metal precursors and glycine as a fuel. Thermodynamic calculations of Y(NO)-2Fe(NO)− nCHNO systems producing YFeO predicted an adiabatic temperature of 2250 K with generating carbon dioxide, nitrogen and water vapor. The considerable gas evolution helps to produce the synthesized powders friable and loosely agglomerated. Adjusting the glycine/metal nitrates ratio can selectively control the crystallite size and magnetodielectric properties of the ferrites. Increasing the glycine content increased the reaction temperature during the SCS and consequently the particle size. Magnetization of zero-field-cooled (ZFC) and field-cooled (FC) ferrites in the temperature range of 1.9-300 K showed different patterns when the fraction of glycine was increased. Analysis of ZFC and FC magnetization curves of annealed samples confirmed that nanoparticles exhibit superparamagnetic behavior. The increasing concentration of glycine leads to escalation of blocking temperature. Reduction of dielectric permittivity (ɛ) toward frequency indicates the relaxation processes in the composites, and the values of ɛ are shifted upward along the operating temperature. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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