Comparing Different Approaches to Form Cobalt Oxide Layer on CoPt Nanoparticles
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Tarih
2020
Dergi Başlığı
Dergi ISSN
Cilt Başlığı
Yayıncı
Adiyaman University
Erişim Hakkı
info:eu-repo/semantics/openAccess
Özet
We have studied the effect of preparation methods, under argon gas and in the air environment, on the cobalt oxide formation of CoPt nanoparticles by the polyol process. The formation of cobalt oxide for both samples was investigated by the x-ray diffraction (XRD) method and cobalt oxide peaks are observed in the air prepared sample. Rietveld refinement analyses revealed that all samples exhibit a chemically distorted cubic crystal structure. The average particle size was determined <8 nm by scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS) was revealed the chemical compositions with possible oxygen formation in the structure. The blocking temperature is reduced to 28 K in the air prepared sample due to cobalt oxide formation. The hysteresis gap disappeared above the blocking temperature and no saturation is observed up to ±5 T external field due to the system switching from ferromagnetic state to paramagnetic state. Similarly, the coercive field was decreased from 1021 Oe to zero with increasing the temperature from 5 K to 300 K. The formations of the cobalt oxide layer did not interact with CoPt nanoparticles, therefore, the maximum exchange bias was observed about 93 Oe at 5 K. © 2020, Adiyaman University. All rights reserved.
Açıklama
Anahtar Kelimeler
Cobalt oxide formation, CoPt NPs, Polyol, PPMS, SEM, XRD
Kaynak
Adiyaman University Journal of Science
WoS Q Değeri
Scopus Q Değeri
Q3
Cilt
10
Sayı
1
