Ferromagnetic transition metal-doped CdS nanoparticles: a comparative study
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Ferromagnetic transition metal-doped CdS nanoparticles: a comparative study Shivani Jindal1 and Puneet Sharma1,* 1
School of Physics & Materials Science, Thapar Institute of Engineering & Technology, Patiala 147004, India
Received: 9 June 2020
ABSTRACT
Accepted: 24 September 2020
In the present work, series of ferromagnetic transition metal-doped (Fe, Co) CdS nanoparticles were synthesized via hydrothermal technique. The particles were characterized for structural, morphological, optical and magnetic properties. The X-ray diffraction confirmed the single wurtzite phase for all compositions. The relatively smaller crystallite size (* 11.50 nm) was obtained with Fe (x = 0.15) compared to Co doping (* 13.88 nm). The HR-TEM micrographs revealed spherical morphology of nanoparticles with decrease in average particle size. The increase in optical band gap was observed with doping. In photoluminescence spectra, the main emission peak at 529 nm corresponds to green emission due to d-d intra ion transition. The magnetic analysis confirmed room temperature ferromagnetism in all the compositions and highest value of saturation magnetization has been observed for Fe-doped nanoparticles.
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Springer Science+Business
Media, LLC, part of Springer Nature 2020
1 Introduction Dilute magnetic semiconductors (DMS) have gained remarkable attention due to their potential application in spintronic devices, solar cells, light emitting diodes and gas sensors [1–5]. These materials exhibit entirely different properties at nanoscale regime compared to their bulk counterpart. The two foremost important properties of these nano materials are existence of suitable bandgap (Eg) which is well exploited for solar cell applications and weak ferromagnetism which is yet to be explored for storage devices. The origin of ferromagnetism in these materials is controversial and has been explained by various types of exchange interactions, i.e., super exchange, double exchange and RKKY interactions
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https://doi.org/10.1007/s10854-020-04549-3
[6]. It is also reported that presence of secondary phases and defects were also contribute to ferromagnetism [7, 8]. However, existence of weak room temperature (RT) magnetization restricts their application in realized devices. Among various II-VI DMS materials, CdS with direct optical Eg of 2.42 eV have been extensively investigated. Various techniques have been employed to synthesize CdS nanostructures such as sol-gel, hydrothermal, chemical co-precipitation, etc. to control particle sizes by suitable process parameter [9–11]. In one of the focuses, the effect of particle size and its distribution were extensively investigated and well established [12, 13]. In another approach, the magnetic and optical properties were tuned by suitable cation doping. The major investigations were
J Mater Sci: Mater Electron
related to rare earth (RE) (Dy, Gd, Tb, Eu etc.) and transition metals (TM) (Fe, Cr, Co etc.) doping using different synthesis techniques [
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