Comparing Different Approaches to Form Cobalt Oxide Layer on CoPt Nanoparticles

Yıl 2020, , 353 - 363, 25.06.2020

Doğan Kaya , İdris Adanur , Mustafa Akyol , Faruk Karadağ , Ahmet Ekicibil

https://doi.org/10.37094/adyujsci.709426

Öz

    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.

Anahtar Kelimeler

CoPt NPs, Cobalt oxide formation, Polyol, XRD, SEM, PPMS

Destekleyen Kurum

Cukurova University

Proje Numarası

FBA-2018-10412

Teşekkür

The authors acknowledge support from Cukurova University, Adana, Turkey, under Scientific Research Funding Grand No: FBA-2018-10412.

Kaynakça

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