SpringerOpen Newsletter

Receive periodic news and updates relating to SpringerOpen.

Open Access Nano Express

Influence of Cobalt Doping on the Physical Properties of Zn0.9Cd0.1S Nanoparticles

Sonal Singhal12, Amit Kumar Chawla1, Hari Om Gupta2 and Ramesh Chandra1*

Author Affiliations

1 Nanoscience Laboratory, Institute Instrumentation Center, Indian Institute of Technology Roorkee, Roorkee, 247667, India

2 Department of Electrical Engineering, Indian Institute of Technology Roorkee, Roorkee, 247667, India

For all author emails, please log on.

Nanoscale Research Letters 2009, 5:323-331  doi:10.1007/s11671-009-9483-7

Published: 17 November 2009

Abstract

Zn0.9Cd0.1S nanoparticles doped with 0.005–0.24 M cobalt have been prepared by co-precipitation technique in ice bath at 280 K. For the cobalt concentration >0.18 M, XRD pattern shows unidentified phases along with Zn0.9Cd0.1S sphalerite phase. For low cobalt concentration (≤0.05 M) particle size, dXRDis ~3.5 nm, while for high cobalt concentration (>0.05 M) particle size decreases abruptly (~2 nm) as detected by XRD. However, TEM analysis shows the similar particle size (~3.5 nm) irrespective of the cobalt concentration. Local strain in the alloyed nanoparticles with cobalt concentration of 0.18 M increases ~46% in comparison to that of 0.05 M. Direct to indirect energy band-gap transition is obtained when cobalt concentration goes beyond 0.05 M. A red shift in energy band gap is also observed for both the cases. Nanoparticles with low cobalt concentrations were found to have paramagnetic nature with no antiferromagnetic coupling. A negative Curie–Weiss temperature of −75 K with antiferromagnetic coupling was obtained for the high cobalt concentration.

Keywords:
Cobalt doping; Paramagnetism; Quantum confinement