A seriesofCr-substitutedNi–Zn ferrites;Ni0.8Zn0.2CrxFe2xO4 (x¼0.0–1.0)werepreparedviaoxalate
decomposition routetocharacterizetheeffectofCr-substitutiononstructural,magneticandelectrical
properties. ThepreparedpowderswerecharacterizedusingX-raydiffraction(XRD),Fouriertransform
infrared(FT-IR)andtransmissionelectronmicroscopy(TEM).XRDindicatedsingle-phasecubicferrites.
The latticeparameters(aExp) exhibitedagradualdecreasewithincreasingchromium,attributedtothe
smaller ionicradiiofCr3þ substituent. Accordingtotheobtainedstructuraldata,anappropriatecation
distribution wassuggestedandfortified throughFT-IRspectroscopybesidesmagneticandelectrical
measurements. TEMimageshowedagglomeratedcubiccrystalswithanaveragesizeofabout20nm.
Vibrating samplemagnetometer(VSM)measurementsindicatedminimalhysteresischaracteristicfor
soft magneticmaterial.Thedecreaseinsaturationmagnetization(Ms) withCr-substitutionwasdiscussed
in viewofNeel’s twosub-latticemodel.ThechangeinthecoercivitywithCr-contentwasdiscussedin
view ofestimatedcationdistributionandmagnetizationvalues.TheobviousfallintheCurietempera-
ture, estimatedfrommolarsusceptibilitymeasurements,withincreasingCr-concentrationswasassigned
to thegradualreplacementofFe3þ ions ontheoctahedralsitesbyparamagneticCr3þ ions. ac-con-
ductivity asafunctionofbothfrequencyandabsolutetemperatureexhibitedasemi-conductingbeha-
vior.ThedecreaseinconductivitywithincreasingCr-contentwasattributedtothepreferentialoccu-
pation ofCr3þ ions byoctahedralsiteswhichreplacingFe3þ ions andlimitingFe2þ
–Fe3þ conduction. |
