Doping induced magnetism in Co-ZnS nanoparticles

Journal Article · Thu Oct 15 00:00:00 EDT 2009 · Journal of Solid State Chemistry

DOI:https://doi.org/10.1016/j.jssc.2009.07.015· OSTI ID:21372320

Sambasivam, S ^[1]; Paul Joseph, D ^[2]; Venkateswaran, C ^[2]

---

1. Center for Condensed Matter Sciences, National Taiwan University, Taipei 10617, Taiwan (China)
2. Materials Science Centre, Department of Nuclear Physics, University of Madras, Guindy Campus, Chennai 600025 (India)

Zn{sub 1-x}Co{sub x}S nanoparticles with x=0, 0.1, 0.2, and 0.3 were synthesized by the co-precipitation method using thiophenol as capping agent. The effect of Co doping on the structural, optical and magnetic properties are investigated. The X-ray diffraction patterns show single phase with cubic structure and the images of Transmission Electron Microscopy indicate an average particle size of 39 nm. Significant blue shift in the optical absorbing band edge was observed with increasing Co doping. In the Co doped samples, room-temperature (RT) magnetic hysteresis is observed and the magnetization reduces with increasing Co content. However, these samples show paramagnetic resonance instead of ferromagnetic resonance at both 300 and 80 K, suggesting that the origin of RT magnetization in these Zn{sub 1-x}Co{sub x}S nanoparticles involves with the frustration of antiferromagnetic interactions. - Graphical abstract: Figure shows the magnetization data of Zn{sub 1-x}Co{sub x}S (0.1<=x<=0.3) nanoparticles annealed at 573 K/2 h in vacuum and measured at 300 K. This interesting feature of systematic reduction in magnetization may be due to introduction of antiferromagnetic ordering with increasing 'Co' concentration which may be due to competition between the antiferromagnetic and ferromagnetic ordering within the sample. One could also observe the exchange bias effect which is an interface interaction observed in a ferromagnetic-antiferromagnetic mixture. The exchange bias field (loop shift) towards negative field was around 63 Oe for the Zn{sub 1-x}Co{sub x}S (0.1<=x<=0.3) nanoparticles.

• OSTI ID: 21372320
• Journal Information: Journal of Solid State Chemistry, Vol. 182, Issue 10; Other Information: DOI: 10.1016/j.jssc.2009.07.015; PII: S0022-4596(09)00316-8; Copyright (c) 2009 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; ISSN 0022-4596
• Country of Publication: United States
• Language: English

Related Subjects

77 NANOSCIENCE AND NANOTECHNOLOGY
ANTIFERROMAGNETISM
COBALT SULFIDES
COPRECIPITATION
DOPED MATERIALS
ELECTRON SPIN RESONANCE
NANOSTRUCTURES
PARAMAGNETISM
TEMPERATURE RANGE 0273-0400 K
TRANSMISSION ELECTRON MICROSCOPY
X-RAY DIFFRACTION
ZINC SULFIDES
CHALCOGENIDES
COBALT COMPOUNDS
COHERENT SCATTERING
DIFFRACTION
ELECTRON MICROSCOPY
INORGANIC PHOSPHORS
MAGNETIC RESONANCE
MAGNETISM
MATERIALS
MICROSCOPY
PHOSPHORS
PRECIPITATION
RESONANCE
SCATTERING
SEPARATION PROCESSES
SULFIDES
SULFUR COMPOUNDS
TEMPERATURE RANGE
TRANSITION ELEMENT COMPOUNDS
ZINC COMPOUNDS