TheeffectofMnsubstitutiononthemagneticanddielectricpropertiesofcobaltferritesynthesizedbyanautocombustionroute

摘要

Co1.2-xMnxFe1.8O4(0 x 0.4)compositionsweresynthesizedbytheautocombustionroutebykeepingtheoxidizertofuelratio( e)at1.Thermogravimetricanalysis(TGA)showsthestablephaseformationtakesplaceatatemperatureabove600-C.Structuralcharacterizationofallthesampleswascarriedoutbythex-raydiffractiontechnique.Roomtemperaturemagnetizationmeasurementsshowedthat,forthesubstitutionofCobyMn,thereisaninitialincreaseinthesaturationmagnetization(Ms)forlowerconcentrations(i.e.x=0.1and0.2);andthenthemagnetizationdecreasesforhigherconcentrations(i.e.x=0.3and0.4).Also,itisobservedthatthecoercivity(Hc)goesondecreasingwiththesubstitutionofMncontent,exceptforx=0.3whichshowsaslightincreaseincoercivityascomparedtox=0.4.Roomtemperaturedielectricproperties,namelyrelativedielectricpermittivity(E ),dielectricloss(tan8)andacconductivity(Oac),forallthesampleswerestudiedasafunctionofappliedfrequencyintherangefrom20Hzto1MHz.ThesestudiesindicatethattherelativedielectricpermittivitygoesonincreasingwiththeincreaseofMncontentinCoferriteandalsoallthesamplesshowtheusualdielectricdispersionwhichisduetotheMaxwell–Wagner-typeinterfacialpolarization.Theacconductivitymeasurementsuggeststhattheconductionisduetosmallpolaronhopping.