Structural magnetic and electrical properties of Mg-based soft ferrites

Abstract

Three series of fen-it< sample, of d\e compositions Mg, .•ZJ',F.,O" Mg" "_,cu,-ZI1<l"O(Fe,O,)~,, and Mgo"Cuo"ZI1<l"O(Fe,.""'n.o,),.,, were prepared by u,ing lhc ,olid <tate reaclion technique. The pha,e identification is carried oul hy nsing the X-ray dilT",cllOll The X_ray di/frac,iun an.lyse, r.,'calcd l~at all the sample, ofthe thrcc ,cries crystallize in singie-phllSo cubic spinel structure. The lalticc con.tanl of Mg,.,Zn,Fe,O, ferrite incre",e, linearly wIth inereasing zinc conlent obeyIng Vegard's law, The continuous docreasc of Curie temper.Me (T,) ofMg,~Zn,Fe,O. with an lncrea>o of Zn" content i.' attributed to the weakening of A_B .xchonge lnt<"otion. Saturation magnetizollon (M,) and magnclic momcnl are observed to inc••a,o up to x ~ 0.4, lhereafter decrease duo to thc 'pm canting In B-,IIOS, T~o obscrved variation in T. and M, ha, bcen explain.d on the basi, of the strength of A.B exchange interaction. 11'e inilial p.rmeablilly b found!o merease with lhe addition of Zn" ion, up to x ~ 0,6. Temp=turc and the frequency dependence of AC ,u,ccptlbility a"d lhe fi.ld.coolod and d,e zero fidd-C<Jolod DC magnetizations are performed for the diMe Mg,. ,Zn,F.,O, (x ~ 0,7, 0,8, 0.9, 1.0) spinel fcrrites, The Mg",Zn~,Fe,O. and Mg."Zn"Fc,O, ferrites show re-.ntrant spIn glass beb.viour w~ile tho samples M£o ,Ztto.,Fe,O, and ZnFc,O, show the spinglas. behaviour, It is observed from t~o frequcncy dependence of AC susceptIbility measurerm",! thaI the freezing temperature s~in, ,lnwly with the measuring frequency, lndioating a spin.glllS' transition of the s"",ples Mg,,,,Z"",,,!'e,O, and ZnF",O,. The samples show a lypical spin_glass behavior with a monifestation of non_equilibrium dynamics, such as agIng, roj~vcnalion and memory .ff.cts, These experimental re,ults 'lrongly indicate that Mg.",Z"""Fe,o, and ZnF",O, f.rrite are subjected to spln-glas. phllSe at very low temperature and Is not canted antifcrromagnet The physleal, mag"etic and electrical transport propertie., of Cu-,ubstlluted M~~".,Cu,Zn, ,,0 (Fe,o,J~" Im-itc. have been 'tudied, The micro.motu,"1 .nd t~o struelural,lnaiyseo were carried om by using a ,canning el.ctron microscupe and X.ray diffraction (XRD). respectively, The laulee parameter is found to increase with increasIng copper contont. A ocmarkable d."sification is ob,erved with the additIon of Cu ions in the ferrit.s, The beneficial effect nf copper ion, on the denslfication of Mg-Zn ferrite ca" b. reMooably .xplalned by possible bimodal diffusion mechanism, Microstrucrural analyse> indicate thai CuO infl~e"ces the microstrucmrc of the !Cmte., by the formmlon of llq~id phase during ,intering. The gr,lo size increase, significantly with increasing copp.r conl.nt. Exaggeralcd gram growth i, observ.d for the samples Wil~ y ~ 0.25 _ 0,35. The real part of initial permeabilily (~') increascs ,harply witb inCreMing concentratIon of Cu Ions. 11';' increase in ~' is expiained with the grain growth mechanism and enbanced densifioation of the fordtes. The resonance frequcrtcie, of all the sample., ,hift toward the low.r frequency as the porm.abilily mcre •••.• with Cu cont<nt, whIch i, in conformily with Snoek's 'elatio". Sinlering tempcralure T, also affects the densific.tion, grain growth and imtial permcability ofth. sampies. Smuration magnetization (M,) increaso' wllh copper onnl",,! up to y - 0.30 and then it decrease, XVI! -- . • which call be explained in 1<:Itnsof tho call on redi,tributio" between A and B ,ublaltices. Diele<ltic cons""'! (e') decrease, rapidl}' with the incre•• c in [rogumc)" at lower frequonoics and ,1",,,ly at higher frcqu£l1ci•• which may be due to lhe Max"dl_Wagner interfacial polarization Dielectric COIl>lantand dielectric loss tangent increase", tho temperature increase" which is attributed to tho fact lhallhc hopping of elec!rons betw •• n Fe'. and F." ion, i, thermally activated on increasing !he tompernture, Mn_sub,llinted Mg,,~sCUo",Zno.<,O(Fe,.,Mt1,O,j",,, (z ~ 0,00, 0.02, 0 04, 0.06, 0,08, 0.10) ferdIe, have .1.'0 been prepared by standard solid state reaction {cdmiquo and charaderi,."d by X-my diffraction. The lattJoe constant is fOUlldto increase linearly with tho in=" in Mn" ion cOtlconlnltion uhcying Vcgard', law. Th. lnib.1 permeability (j.l')of the Mn-sub,(ilutod Mg-Cu-Zn ferrito' exhibits th.rn",l hy.t=SlS whon the temrcrature is cycled th:Jm abovo the Curie temperature Tc 10 below The sharp decrea,e of j.l' at T - T, indicates that tho samplos hav. high homogeneity. The T, of lho studied sarnpios waS ddormined Ii-om the fl'- T cur"e, wh"", Hopkin,on type of effect at the T, has been obsorv<d with tho manifo,t.(ion of ,harp fall of permeabiiity. T, is found to increase with increasing Mn con'<rI!. Inilial pennoab;lity change, apPTcciably wi~, Mn .ddition, which is otrributed to the reduction of m'W'oloolriction constant due (0 .ddition of Mn. The value, of relative 100' factor (RLF) found in the investig.ted ferrires are in the ordor of 10--4 up 10freq~<rIcy 2 MHz which eXlonds 10 higher frequ<rley range as the Mn content i, im:rc:ascd DC dcclrieal resistivity increases significantly Wilh the increase of Mn-eonlen!. The AC rc:,i,tivity (PAc) and didoctrie oonstant (0') of the ,ampio, lITefound to decrease witi, inerea,mg frequency exhibiting nQrmal li:rrimagm:tic behaviour Dielectrio rei.""tion peak, were ob""r"ed fur ~,e mquency dopcndenoo of dielectric loss tangent curves. The.' ioeroa,e, as tho temperature increases which is tbe normal dielectric behaviour of the mO&l'elic semico"duCIOr ferrile. The obson<d vari.tlon of electrical and dielectric properties i, explained on the basi, of Fe><-iFeHionic coneo"!ralio" as weli as the eieelronie bopping ftequ<rlcy b<tween Fe" and Fo'"' ions. Ferrite nanoparticJes of MgFe,O,. M~"Znr...,Fe,O. and Mg.",,zn,,,Cu.,.,Fe,O, have b""n ,ynrl,e,i:ocd by using chemical co_proclpitation method and charaotenzed by X-ray diffraction.