The room-temperature saturation magnetization of CdxMn1-xFe2O4 decreased with increasing cadmium concentration. When 0 \u3c x \u3c 0.5, the decrease in saturation magnetization was due to the increase in the amount of non-mgnetic distorted cubic Cd(Mn, Fe) 2O4

Jong, B. W.

Ownby, P. D.

English

Missouri University of Science and Technology (Missouri S&T): Scholars' Mine

Missouri University of Science and Technology Scholars' Mine Materials Science and Engineering Faculty Research & Creative Works Materials Science and Engineering 01 Jan 1974 Magnetic Properties of Cadmium Manganese Ferrite B. W. Jong P. D. Ownby Missouri University of Science and Technology, ownby@mst.edu Follow this and additional works at: https://scholarsmine.mst.edu/matsci_eng_facwork  Part of the Materials Science and Engineering Commons Recommended Citation B. W. Jong and P. D. Ownby, "Magnetic Properties of Cadmium Manganese Ferrite," IEEE Transactions on Magnetics, Institute of Electrical and Electronics Engineers (IEEE), Jan 1974. The definitive version is available at https://doi.org/10.1109/TMAG.1974.1058444 This Article - Journal is brought to you for free and open access by Scholars' Mine. It has been accepted for inclusion in Materials Science and Engineering Faculty Research & Creative Works by an authorized administrator of Scholars' Mine. This work is protected by U. S. Copyright Law. Unauthorized use including reproduction for redistribution requires the permission of the copyright holder. For more information, please contact scholarsmine@mst.edu. MAQ\TETIC PROPERTIES  OF MANGANESE FERRITE Sing W. Jong and P. Darrell Ownby ABSTRACT The room-temperature saturation magnetization of Cd-$nl-,FenOlr decreased w i t h  increasing cadmium con- centration. . when 0 < x 6 0.5, the decrease in  satura- tion magnetization was due to the increase in the amount of  non-mgnetic distorted  cubic Cd(M.n,Fe) 204 which formed as x was increased. The saturation mag- netization became very small for x > 0.5 due to  the formation of (Cd,Fe) (Mn,Fe) 201,. the  porosity played a significant  role  in changing the hysteresis loop parameters of Cd#q -,Fe2O4. The max- innnn Br/Bm was obtained at  x = 0.3 due to  the combina- tion of a smaller grain size and a more homogeneous grain size distribution. A higher porosity at  x = 0 and a smaller grain  size a t  x = 0.3 accounted for a larger coercive  field  strength  for  these compositions. The grain size, the  grain  size  distribution and INFRODULTION Eichbaum studied CdMn-ferrites for  use in  high speed computer  components [1]. Eichbaum also studied the  effect of boron on square-loop  CdMn-ferrites- [2].  Cadmim-containing Zr$vln:ferrite systems were investi- gated by b i r d   e t .  al. [ 31. However, these investiga- tions were not  primarily designed to determine the  ef- fect of cadmiun on the magnetic properti,es. Moreover, the compositions which they studied were different from those in the present work. The solid-state  reaction sequence and optimum time-temperature and fabrication regime for producing cadmium manganese f e r r i t e  have recently been discussed elsewhere [4]. Figure 1 shows the variation in  (311) d-spacing of CdFe7-04 with cadmiun concentration, x, when  CcMn2O4 dissolved in CdFe2O4 for  the composition xCd0 + (1-x)MnC03 + a-FezO3 reacted a t  900°C for  2 hours. The knee in the d-spacing vs. composition c q v e   a t  x = 0.5 has been described in detail  indicat- ing that a l l  of the Mn304 w a s  dissolved in  the Cd(M.n,Fe) 204 for 0.5 < x e 1.0 a t   t h i s  temperature [4 ] .  A single phase of C w 1 - + 2 O 4  existed a t  1150OC. This paper w i l l  correlate these results with the magnetic properties. In this work, the  effects of cadmium content on the physical properties, magnetic properties and mic- rostructure were studied. Careful control over pro- cessing variables was exercised so that the amolglt of powder, ball milling parameters, calcination and sin- tering time-temperature cycles were fixed  for each composition batch. Manuscript received March 25, 1974; revised May 22, 1974. Paper 9.9, presented at  the 1974 INTERMAG conference Toronto, C a n a d a ,  May 14-17. This work was supported by a fellowship grant from the Fmerson Electric Co. Engineering, University of Missouri-Rolla, Rolla, Mo. 65401. He is now with Engineering Experiment Station, Georgia Insti tute o f  Technology, Atlanta, Georgia 30332. P. D. M y  is with the Department of Ceramic Engineering and Graduate Center for  Materials Resear- ch, University of Missouri-Rolla, Rolla, Mo. 65401. B. W. Jong was with the Department of Ceramic 619 2.62 - - - 2.40 "5 =: - - U m 2.58 - + t M904 2.54 I I i l 1 1 l I I -  0.0 0.2 0.4 0.6 0.8 1.0 CADMIUM CONCENTRATION ( X  ) Figure 1. Variation i n  (311) d-spacing of CdFe204 with cadmium concentration, x, when  CdMn2Ot, dissolved i n  CdFe20,, for  the composition xCd0 + (1-x)MnCO + a-Fez03 reacted at  9OOOC for 2 hours. EXPERIMENTAL A. Sample Preparation + a-FepQ3, where x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7 and 0.9 were calcined a t  900°C for 2 hours. The percent of Cd@h,Fe)201+ formed was calculated from X- ray diffraction intensities as follows: Percent conversion = I311[Cd(l~fn,Fe)204] x lOO/{I311 [CdW,Fe)2041 + I111(Cdo) + I211W304) + 1104 (a-Fe$&) 1 Distilled water slurries containing 60% solids were steel-ball milled for 16 hours. The dried and gram- lated  calcined powder was uniaxially  pressed at 4.22 x l o 5  kg/m2 into 1.91 an diameter, 0.32 cm high pel- l e t s  and into 3.66 an outside diameter, 2.77 an inside diameter, by 0.51 an high toroids and then isostati-  cally pressed to  1.76 x l o 7 -  kg/m2. side, in  air, in   t ight ly  covered cylindrical alumina crucibles at  1150°C for  30 minutes and air-quenched. The sintered  pellets were then used for  the measure- ments of sintered density, saturation magnetization and characterization of microstructure. The sintered toroids were used for  studies of hysteresis-loop parameters. B . Measurement dimensions obtained by standard X-ray technique. Sintered  densities were measured by using Archimedes' principle. Saturation  magnetization w a s  measured at  room temperature using a vibrating sample magnetometer and an applied field of 5 We. The standard against which the CdMn-ferrite spheres were compared was a 99.999% nickel which was checked by various laboratories in the ferrite industry. The 4nMs o f  N i  was  6100 G. 100-gram batches  with composition xCdO+(l-x)ElncO3 The pellets and toroids were sintered side-by- X-ray densities were calculated from unit ce l l  The measurements of Br/Bm and coercive  field  strength were made using an a-c dynamic method described by Soohoo [ 51. Br/h is defined as the ratio of the re- m e n t  magnetization, Br,  to the maximum magnetiza- tion, Bm, a t  a drive of 5 Oe. ing  electron microscope. Microstructures were characterized using a scann- RESULTS AND DISCUSSION A. Relative Density tion  of cadmium concentration  are  plotted  in Figure 2. It  can be seen tha t   a l l  cadmium concentrations studied increased the relative density to s98% of theoretical whereas without cadmium, only c89% of the theoretical value was reached. The theoretical and sintered density as a func- I 4.6 4.4 0.0 0.2 0.4 0.6 0.8 1.0 CADMIUM  CONCENTRATION (X) Figure 2. X-ray density and sintered density vs. cad- mium concentration, x, for C%Mn1-  FenOs. Specimens were sintered at  1150OC f o r  30 minutes. B. Magnetic Properties this  is the f i r s t  and most complete characterization of cadmium  manganese fe r r i te  published to  date. The changes in the saturation magnetization, B r / h  and coercive  field  strength were measured as the cadmium concentration, x, was increased. a. Saturation magnetization Figure 3 shows the measured room-temperature sa- turation magnetization, 4&, versus Cd concentration, x, in the solid solution of C+hh1-,Fe201, and percent conversion to  Cd(b,Fe) 204 versus Cd concentration, x, for the composition xCd0 + (l-x)MO3 + a-FezO3 reacted a t  900°C for 2 hours. I t  can be seen that the saturation magnetization of Cd$nl -  Fezoh de- creased as the non-magnetic phase of Cd$h,Fe)201+ progressively increased. The saturation magnetization decreased slowly, as x increased. from 0 t o  0.2, and then more rapidly to  x = 0.5. The percent of Cd@fn,Fe)201+ increased to  As far as the authors have been able to determine -82% when the Cd concentration, x, was 0.2. The influence of the cation distribution on the 4& can easily be understood by considering the  solid state formation sequence [41. The reaction sequence is simplified as follows: Fez03 CdO  CdFe2O4 Mn203 60O0-800oC * C&h,O,  9 OOC ' Cd@"%Fe)204 I I % O i i I ' " ' ? ' J  --___. , I  0 0.0 0.2 0.4 0.6 0.8 1.0 CADMIUM CONCENTRATION ( X )  Figure 3. Room-temperature saturation magnetization vs. cadmium concentration, x, for 204 and percent conversion to  for the composition xCd0 + (l-x)MnC03 + a-Fe203 reacted at 900°C for  2 hours. vs. cadmium concentration, x, A t  900°C, a l l  available Cd2+ and some Mn3+ and some Fe3+ have formed Cd(Mn,Fe) 204 which coexist w i t h  Mn30, and a-Fe203. A single phase of CdMn-ferrite formed by the  dissolution of Cd(Mn,Fe),O, into MnFez04 a t  115OOC. It is known that Cd2+ preferentially occu- pies  the  tetrahedral  sites. When  CdFe204  CdM1-1204 and Cd(k,Fe),O, are formed some Mn3+ and Fe3: are forced into the octahedral sites. h3+ is a Jahn-Teller ion [6,7] which w i l l  distort the spinel structure. The Cd(bh,Fe)204 was found to  be elongated in the c-axis with c/a > 1.0 i n   a l l  compositions 0 < x < 1.0 [4] .  Baltzer etc. have shown that  symetry  distortion can strongly influence the magnetic properties [ 8 ] .  Jacobs found triangular moment arrangements in  the distorted spinel structure M.Mn204 [ 9 ]  in agreement w i t h  the Yafet-Kittel model for  antiferromagnetic ar- rangements in  fe r r i te  [IO]. I t  appears that the non- magnetic, distorted Cd(Mn,Fe),04 has affected the sa- turation magnetization of Cw1-xFe20s. In this com- position range, the system can be considered as s(O-SO%)Cd(Mn,Fe)20t, + s(100-10%)MnFe204. Obviously, the saturation magnetization  of Cd I - ~ F ~ ~ O ,  is de- creased by increasing  the amount o ipl Cd(h,Fe)204 dis- solving into the MnFenOs. When x = 0.5, the saturation magnetization drops to a very low value and as x -j. 1.0 it approaches zero. The drop in  magnetization w a s  also confirmed by the dynamic hysteresigrams of Cd$fnl- Fez04 as shown in Figure 4 .  No hysteresis loop coufd be displayed when x % 0.6. The cation  distribution can also be shown from 620 Figure 4. Dynamic 1 kHz hysteresigrams vs. cadmium concentration, x, for  Cd@l-,Fe204. Major divisions of vertical  scale 600 G; major divisions of horizontal scale 3 Oe. A t  9OOOC, a l l  available Cd2+ and Mn3+, and some Fe3+ have formed the Cd(Mn,Fe)204 existing w i t h  a-Fe203. A single phase of (Cd,Fe) m,Fe)204 w a s  formed at  115OOC. In this composition range, the sys- tem is ~(90-100%)Cd(Mn,Fe)~O~ + ~(10-0%)a -Fe~0~ .  Theiron appears to  be distributed  in the tetrahedral and octahedral sites so as to  form a solid solution (Cd,Fe) (Mn,Fe) 204 which exhibits very low magnetiza- tion. The thermal effect  on the spin alignment is not considered i n  this paper. Future work w i l l  in- clude a saturation magnetization study of Cd$fnl-,- Fe,O, near Oo K and classification of magnetic char- acterist ics of C d w ,  Fe) 204 and (Cd,Fe) W,Fe) 204. Both Cd and Zn strongly  prefer  the  tetrahedral s i tes  and are non-magnetic. Therefore, a comparison was made for  room-temperature 417% of Cd.$r11-~Fe20~ w i t h  the corresponding Zn$k~-~Fe204 [11,12,13]. For comparison, the 417% was corrected to the value which was equivalent to the X-ray density. There are no differences in 4nMs for x = 0 and x a 0.8. MnFe204 is the same in each case for x = 0 and when x 3 0.8 for Zn$nl-$e204 it appears to  be similar to  when x > 0.5 for  C ~ i . p n ~ - ~ F e ~ O ~  described previously. 0.2 6 x < 0.8. Cd&fnl - Fez04 has a lower value of 4vMs than the corresponzing ZrQlnl-,Fe;lO~, i n  these compositions. This is probably due to  a different ionic radius, ( Cd2+ is 0.92 1 which is larger than Zn2+, 0.69 1 [141 ) resulting in a mre distorted spinel, ( Cdhh2O4 w i t h  c/a = 1.20 and ZrMn2O4 w i t h  c/a = 1.14 [15,16] ). b. Hysteresis loop  parameters Figure 5 shows the Br/b rat io  and coercive field strength, a t  a drive of 5 Oe and 1 kHz, versus cadmiun concentration. The coercive field strength of zero cadmium concentration is larger  than when x > 0 be- cause of the lowered sintered density a t  x = 0. This agrees with Wijn etc. who found that porosity strongly influenced the  coercive  field  strength, pores being non-magnetic inclusions [17]. After the ini t ia l  drop, as the cadmium concentration increases, both the Br/Bm and the coercive field strength increase reaching a maximum a t  x = 0.3.  There are substantial differences in  the 4nMs for 1 .o I  t 0.8 - - 0.6 - & - . k m 0.4 - 0.0 0.2 0.4 0.6 0.8 CADMIUM CONCENTRATION ( X )  Figure 5. Br/Bm and coercive field strength at a drive of 5 Oe and 1 kHz vs. cadmim con- centration, x, for Cd$nl-,Fe20~. Microstructures of various composition were char- acterized  using a scanning electron microscope. Beyond x = 0.3, the grain size was larger and less homogeneous.  The hysteresis loop is microstructure sensitive and also dependent on the  intrinsic magne- tostriction constant, The present work only considers the microstructure. The grain size and grain size distribution  affect  the Br/Em ratio  for  the  solid so- lution of Cd@l-,Fe?04., A smaller grain size and a more homogeneous gram  size  distribution produce a higher Br/Bm, and a smaller grain size or a higher porosity produce a larger  coercive  field  strength. The microstructure appears t o  be composition sensi- tive. A future paper w i l l  be written on the magneto- s t r ic t ion and thermodynamic studies of CdxMn1-xFez04. CONCLUSIONS I t  has been shown that the room-temperature satu- ration magnetization of Cd#nl-,Fe201, decreased with increasing cadmium concentration. The fact  that  the saturation magnetization was correlated  to  the forma- 621 tion sequence was verified. When 0 c x 6 0,5, a l l  available Cd2+ preferentially occupy the  tetrahedral sites forcing some Mn3+ and some Fe3+ into the octahe- dral   si tes,  forming the non-magnetic distorted cubic Cd@,  Fe) 204 which coexisted with phases of  b@, and a-Fe203 a t  900°C. A t  1150°C, a single phase of C&- fe r r i te  w a s  formed by dissolving Cd(Mn,Fe)204 into MnFe204. The saturation magnetization of CdMn-ferrite was then decreased due to the increase in the amount of C d w ,  Fe) 204 formation as x was increased. When 0.5 x < 1.0, a l l  available Cd2+ and M3+, and Fe3+ formed the Cd(Mn,Fe)203 existing w i t h  a-FepO3 at  900°C. A t  1150°C, a single phase of (Cd,Fe) (Mr1,Pe)~0~ was formed, which exhibited very low magnetization. I t  has also been shown that the  grain size and grain  size  distribution changed w i t h  the Br/h rat io  and that  the  porosity  or  the  grain  size changed w i t h  the value of coercive  field  strength  for Cd$4nl-xFe204 and a correlation was inferred. REFERENCES B. R. Eichbaum, "Evaluation of New High-speed Magnetic Ferrite System for Use in  Computer Corn ponents , I '  J. Appl. Phys., Supplement to  vol 30, pp. 49-52s, April 1959. B. R. Eichbaum, "Effect of Boron on Square-hop Cadmium Manganese Ferrites," J. Am. Cer. Soc., vol. 44, pp.  51-54, February 1961. D. H. b i r d ,  et,  a l . ,  "Cadmium-Substituted Fer- rite Materials," U.S. Patent no. 3,400,169, April 22, 1969. B. W. Jong and P. D. Ownby, "Formation and Densi- fication of Cadmium Manganese Ferrite," Am. Cer. SOC. B u l l . ,  V O ~ .  52, pp. 526-528, J ~ n e  1973. Ronald F. Soohoo, "Theory and Application of Fer- rites,"  Prentice-Hall , Inc. , Englewood Cliffs,  New Jersey, 1960. pp. 110-111. G. Blasse, "Properties of Magnetic Compomds in  Connection with Their Crystal Chemistry," Pro- gress in Ceramic Science, ed. by J. E. Burke, Pergamon Press, vol. 4, pp. 133-193, 1966. H. A. Jahn and E. Teller, "Stability of Polyato- mic Molecules in  Degenerate Electronic States I- Orbital Degeneracy," hoc .  Roy. SOC. A161,  pp. Philip K. Baltzer and Peter J. Wojtowicz, "On the  Origin of Low bments  in Chromim-Containing Spinels," J. Appl . Phys , Supplement t o  vol. 30 , pp. 27s-29s. April 1959. I. S. Jacobs, "Evidence for Triangular Moment Arrangements in M-Mn 0, J. Phys . Chem. Solids, Y. Yafet and C. Kittel, "Antiferromagnetic Ar- rangements in Ferrite." Phvs. rev. vol. 87, no. 220-235, 1937. Vol. 11, pp" 1-11, 1659. I I ,  2, pp:  290-294,  1952, C, Gulllaud and H. Vreveaux, "hopribti% Ferro- magn6tiques des Ferrites Mixtes de Cobalt et de Zinc et  de Mamanese e t  de Z i n c , "  C. R. Acad. Sci., vol. 230; pp. 1458, 1950, E. W. Gorter, "Sone Properties of Ferrites in Connection with Their Chemistry," Proceedings of the IRE, vol. 43, pp. 1945-1973, 1955, Wilhelm H. Von Aulock, Wandbook of Microwave Ferrite Materials," Academic Press, New York, pp* F. A. Cotton and G. Wilkinson, "Advanced Inor- ganic Chemistry," A Comprehensive Text, Inter- science Publishers, New York, pp. 45, 1962. A. P. B. Sinha, M. R. Sanjam and A, A. Biswas, "The Structuse of Some Manganites," Acta C r y s t .  J. D. mitz and L. E. Orgel, "Electronic Pro- perties of Transition-Metal Oxide-I," Distortion from Cubic Symmetry," J. Phys. Chem. %lids,  vol. 3, pp. 20-29, 1957. H. P. J. Wijn, E. W. Gorter, C. J, Esveldt and P. Geldermans, "Conditions for  Square Hysteresis Loops in Ferrites," Phillips Technical Review 341-343 and pp. 308, 1965. V O ~ .  10, pp.  439-440.  1957. V O ~ .  16, pp. 49-58, 1954. 622 

Magnetic Properties of Cadmium Manganese Ferrite

https://scholarsmine.mst.edu/cgi/viewcontent.cgi?article=2473&context=matsci_eng_facwork

Magnetic Properties of Cadmium Manganese Ferrite

Abstract

Similar works

Full text

Available Versions

Missouri University of Science and Technology (Missouri S&T): Scholars' Mine