The innovation engine for new materials

Willie Wesley

2009 Summer Intern


Jackson State University




Brent Melot

Faculty Sponsor(s): 

Ram Seshadri

Faculty Sponsor's Department(s): 

Chemistry and Biochemistry

Project Title: 


Project Description: 

ZnCr2O4 and CoCr2O4 are two well studied magnetic spinel complex oxide systems. The spinel structure consists of the formula AB2O4. Both the A and B sites are coordinated by oxygen with the A site being tetrahedral and the B site octahedral. CoCr2O4 has been found to exhibit Neel ferrimagnetic characteristic along with commensurate, incommensurate, and non collinear magnetic ordering [1]. Further studies of CoCr2O4 have been carried out to investigate the spinel’s polar behavior. Research has also found magneto-dielectric anomalies exhibited by the CoCr2O4 system. Anomalies such as long-range ferrimagnetic ordering below a Tc = 94K and a phase transition at Ts = 27K, which was attributed to the beginning of long-range spiral magnetic ordering, have also been discovered in this system [2]. Unlike its more magnetically active counterpart, CoCr2O4, ZnCr2O4 is antiferromagentically frustrated. The non-magnetic d10 Zn cation, which occupies the A site, accounts for this frustration. In this research we examined changes or connections of the dielectric constant and magnetic properties of the CoCr2O4 system with the addition of Zn to the spinel structure. Previous studies by our group have revealed a shift from ferromagnetic and conical ground states to an antiferromagentically frustrated system with the addition of Zn to the CoCr2O4 spinel. Solid solutions in the system Co1-XZnXCr2O4 were prepared at X = 0.2, 0.4, 0.45, 0.5, 0.55, 0.6, 0.8, and 1.0 and the effect on its magnetism and dielectric constant will be measured. Magneto-dielectric lattice coupling anomalies are being studied to gain a better understanding of the system. [1] Melot B et al 2009 J. Phys.: Condens. Matter 21 216007 (7pp) [2] Melot B Phys. Rev. B 74, 024413 (2006)