Study on sintering process and characteristic of nanosized soft magnetic MnZn ferrite powders

School of Materials Science and Engineering, Hebei University of Technology, Ho-pei-ts’un, Beijing, China
Rare Metals (Impact Factor: 1.01). 10/2006; 25(6):531-535. DOI: 10.1016/S1001-0521(07)60139-9


The effect of sintering process (especially the sintering temperature) on the magnetic property and microstructure of sintered sample of nanosized soft magnetic MnZn ferrite powder was investigated. The sintered sample of MnZn ferrite was prepared by both traditional pressing and cool isostatic pressing on MnZn ferrite nanoparticals. The sintering process of which was segmented. The density, microstructure and phase composition of sintered sample were analyzed by Archimedes' law, scanning electron microscopy (SEM) and X-ray diffraction (XRD). The grain growth and densification in sintering process of MnZn ferrite were investigated. The magnetic property was measured by vibrating sample magnetometer (VSM) and Nim2000 magnetic material testing system. The results show that the better sintering temperature is 850 °C, at which the better magnetic property and microstructure of sintered compact were obtained.

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    • "For several past decades, studies of the relationship between morphological properties and magnetic properties of soft ferrites have been focusing only on the product of the final sintering temperature largely neglecting the parallel evolutions of morphological and magnetic properties [15] [16] [17] [18] [19]. Although the effects of sintering temperature on NiZn ferrites properties have been reported elsewhere [20] [21] [22], to the best of our knowledge no study has been found in the literature attempting to correlate the microstructure with the magnetic properties of a single bulk sample produced via mechanically alloyed nanosized powders and later subjected to sintering temperatures from 500 1C up to 1400 1C. Single-sample sintering is very different from multi-sample sintering due to repeated sintering yielding a single thermal history within the studied material. "
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    ABSTRACT: Wereportonaninvestigationtounravelthedependenceofmagneticpropertiesonmicrostructurewhilethey evolveinparallelundertheinfluenceofsinteringtemperatureofasinglesampleofNi0.5Zn0.5Fe2O4 synthesized viamechanicalalloying.Asinglesample,insteadofthe normallypracticedapproachofusingmultiplesamples, wassinteredatvarioussinteringtemperaturesfrom500 1C to14001C. Themorphologyofthesampleswas studiedbymeansofscanningelectronmicroscopy(SEM)equippedwithEDX;densitymeasurementwas conductedusingtheArchimedesprinciple;andhysteresismeasurementwascarriedoutusinga B–H hysteresisgraphsystem.XRDdatashowedthatthe first appearanceofasinglephasewasat800 1C andan amorphousphasewastracedatlowersinteringtemperatures.Wecorrelatedthemicrostructureandthe magneticpropertiesandshowedthattheimportantgrain-sizethresholdfortheappearanceofsignificant orderedmagnetism(mainlyferromagnetism)wasabout Z0.3 mm.Wefoundthattherewerethreestagesof magneticphaseevolutionproducedviathesinteringprocesswithincreasingtemperatures.The first stagewas dominatedbyparamagneticstateswithsomesuperparamagneticbehavior;thesecondstagewasinfluenced bymoderatelyferromagneticstatesandsomeparamagneticstates;andthethirdstageconsistedofstrongly ferromagneticstateswithnegligibleparamagneticstates.Wefoundthatthreefactorssensitivelyinfluencedthe sample'scontentoforderedmagnetism—theferrite-phasecrystallinitydegree,thenumberofgrainsabovethe criticalgrainsizeandthenumberoflargeenoughgrainsfordomainwallaccommodation.
    Journal of Magnetism and Magnetic Materials 02/2014; 351:16-24. DOI:10.1016/j.jmmm.2013.09.041 · 1.97 Impact Factor