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Structural and magnetic properties of sol-gel synthesized Co doped ZnO nanocrystals

RAVI CHANDER1

Affiliation

  1. Semiconductor Laboratory, Physics Department, Guru Nanak Dev University, Amritsar, India

Abstract

We have synthesized Co doped ZnO by Sol gel synthesis technique at varying Co concentration. The synthesis involves formation of metal cation- PEG complex, which is later heated to obtain the desired phase. The TGA-DTA studies were performed onto gel to know about Oxidation temperature of metal complex. The oxidation of metal complex was found to exhibit at ~380o C. The gel was dried at different temperature above the oxidation temperature to obtain powder and was structurally characterized by XRD, SEM and TEM. Gel heated up to 400o C were found to have single phase for all Co concentrations while gel heated above 400o C had shown the phase separation for 20 at% Co concentration having wurtzite ZnO phase and spinel ZnCo2O4 phase. The c-axis lattice parameter of wurtzite phase showed a monotonic decrease with Co doping and was found to follow Vegards law. SEM studies showed that grains of size 20-30nm were agglomerated in about 150nm particle size. TEM studies showed the crystalline nature of the grains. Compositional analysis performed using EDAX as well as ICPAES technique revealed higher Co content for moderate doping upto 5 at% while for 10 at% the Co content found in the powder were quite small upto 7.3%. Both the techniques showed almost same compositions. The magnetic studies were performed onto sample having 10 at% Co and calcined at 400o C. The powder showed paramagnetic behavior and no sign of ferromagnetism was found in the samples..

Keywords

Nanocrystals, Sol-gel technique, Paramagnetic behavior.

Submitted at: March 9, 2011
Accepted at: April 11, 2011

Citation

RAVI CHANDER, Structural and magnetic properties of sol-gel synthesized Co doped ZnO nanocrystals, Journal of Optoelectronics and Advanced Materials Vol. 13, Iss. 4, pp. 409-411 (2011)