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A study on FePB ultrafine amorphous alloy particles
Jomal
of MagMsm
anti Magnetic MateriaIs MCI-144
W95)413-414
ELSEirIER
A studyon Fe-P-B ultrafine amorphousalloy Z. Hu *, Y. Fan, Y. Wu, Q. Yan, Y. Chen Department of Chemistq Nanjing University, Naniing 210093, China
4bshTict Fe,,-,-,P,B, u!trafmc amorphous alloy particles with 3.6 5 x I 10.5 and 6.6 s y .S 32.0 were systemat by chemical reduction. Information about the preparation mechanism, the particle sixes, the crystaikatiou of t and the interaction between the elements was obtained by Miksbauer spectroscopy and several other means.
Ultrafine amorphous alloy particles WAAP~ containing mono-metalloid such as C and B have been widely studied in the past few years [l-3]. Recently, we have reported the chemical preparation of a new system of Fe-P-B through reaction of FeCl,, NaH,P02 and KBH, in aqueous solution [4]. Since P and Et have different electron afEn@, the coexistence of the bi-metalloid elements iu the amorphous alloy may extend the possibility to regulate the powder properties. Obviously, it is worthwhile to study the preparation process a sd thereby the preparation mechanism, and to regulate the compositions in a wider range. In the present work, Fe,,-,-,P,B, U&P with 3.6 1x5 10.5 and 6.6 ly I 32.0 were systemaktlly produced and investigated. 5.40 g FeCl, - 6H,O and 4.24 g NaH,PO, +H,O were first dissolved in water separately then mixed. The pH of the mixture was regulated by adding NaOH solution. Finally, the volume of the mixture with definite pH was kept in 100 ml. Each sample was prepared by adding 100 ml 1 mol. L-’ KBH, solution into the above mixture (series A) or vice versa (series B) within 10 minutes under ultrasonic agitation. The detailed procedure was similar to that reported elsewhere [4]. Thermal treatments were performed at given temperatures below 700°C for 2 h in flowing H, with the rate of 60 mI - mitt-‘. The compositions were analyzed by an inductively coupled plasma method (ICP), X-ray diffraction (XRD) measurements were performed by using FeKa radiation. All isomer shit% of the MBssbauer spectra are given relative to a-iron. Differential scanning calorimetric (DSC) experiments was carried out in pure argon with a heating rate of 20 K * mitt-‘. The morphology and particle sixes were observed by the transmission electron microscopy 0W+vf). During preparation, it is found that Fe’+ reacted with H,PO; and formed Fe(H,PO,), co!loid which reacted
* Corresponding author. Fax: +86-25-3317761.
with KBH4 in the solution. The mu ment in liquid phase resulted in
was increased by adding NaOH
increases with pH, which is carsed by the decreasing of reaction rate in higher pH [5]. It can be seen that H
Tabk I tntlueace of pH vatue on cotnposition, mean particle average hyperfine field (HI Composition Sample pH d blul) Al 1.5 200 Wcd’,o.s B,, A2 2.5 F%.oP,.ohs.o 3@J A3 3.5 haJW329.1. * A4 5 hs&aBzw 6Qfl 1.5 Bl %d’wBm 130 B2 2.5 Fen,kd%2 o 23 B3 35 360 %dW~.o 470 84 5 Fe64.3P3.7B32.0
0304-8853/95/$09.50 Q 1995 Elsevier Scieze B.V. All rights reserved SSDI 0304-8853(94)01517-l
size (d) Ii m 23.3 22.2 18.7 19.0 22.2 19.7 19.9 t9.9
hyperlirrefield
total metalloid content(P + B)
trk profiki of series B (b).
Fe-P-B
2b-B2). Accordmgly,it is suggestedthatthereis a stronger bonding tendencybetweenFe and P than betweenFe and B, i.e., the preferentialbonding of Fed-Pto Fe-B *bondin Fe-P-B samples.Basedon this suggestion,it is reasonable to argue that the crystallization products will be mainly composedof cr-Feand Fe-P compoundsfor highP-contentsamples,while there will still be some Fe-l3 compoundsformed during crystallizationfor low-P-contentsamples.In order to prove this opinion, thecrystallization of Fe,P,B, sample was investigated.From XRD patterns,it is seenthatwhen annealingtemperature(T,) is lower than 3OO“C,the intensity of the halo peak around 28 = 57” increasesgradually with TA’This indicated that structuralrelaxation occurred,which induced the ordering of the atomic arrangements.When 3@ls TA2 35OT, the samplebeganto crystallizeand a characteristicsharppeak correspondingto cy-Fe(ll0) diffraction and a tracepeakto Fe$‘(lll) appeared.The continuousrising of TA resulted in full crystallization.At TA= SWC, severalcharacteristic diflkxtion peaks for Fe,P compound appeared.The annealing at TA= 6OO’Ccausedthe sintering and growth of cr-Femicrocrystakas determinedby the obvious decrease of full width at half maximumfor (110) diffraction peak from 0.5” at TA= SOOT to 0.3” at T, = 6130°C.Further annealingat TA= 700°Cdid not bring aboutvisible change in XRD pattern.This processwasconfirmedby Kssbauer experimentalresults.Anyway, it can be concluded that neither Fe,B, Fe,B nor other F&I speciesappeared during the annealingtreatment.However,for sampleA3, which was chosento investigatethe crystallizationof the low-P-content sample, Fe,B species with H= 23.8 T, IS=0.09mm~s-‘andQS=0.07mm~s-‘inM6ssbauer spectrumappearedafter annealingat 64O’C. In summary,Fe,,-,-,P,B, amorphouspowderswith 3.6 LX 5 10.5and 6.6 I y 5 32.0were systematicallyproducedand the experimentalresultssuggesteda preferential bonding of Fe-P to Fe-B bond. Acknowkfgqments:This work has been supportedby NNSFCand CPSF.
[l] J. van Wonterghem, S. Morup, S.W. Charles, S. Wells andJ. Villadsen, Phys. Rev. L&t. 55 (1985) 410. [2] J. van Wonterghem, S. Morup, C.I.W. Koch, S.W. Charles and S. W&s, Nature 322 (1986) 622. [3] S. Linderolh, Hyperfine Interactions 68 (1991) 107. [4] J. Shen, Z. Hu, Y. Hsiaand Y. Chen, Appl. Phys. L&t. 59 (1991) 3545. IS] S. Linderoth and S. Morup,J. Appl. Phys. 69 (1991) 5256.
of MagMsm
anti Magnetic MateriaIs MCI-144
W95)413-414
ELSEirIER
A studyon Fe-P-B ultrafine amorphousalloy Z. Hu *, Y. Fan, Y. Wu, Q. Yan, Y. Chen Department of Chemistq Nanjing University, Naniing 210093, China
4bshTict Fe,,-,-,P,B, u!trafmc amorphous alloy particles with 3.6 5 x I 10.5 and 6.6 s y .S 32.0 were systemat by chemical reduction. Information about the preparation mechanism, the particle sixes, the crystaikatiou of t and the interaction between the elements was obtained by Miksbauer spectroscopy and several other means.
Ultrafine amorphous alloy particles WAAP~ containing mono-metalloid such as C and B have been widely studied in the past few years [l-3]. Recently, we have reported the chemical preparation of a new system of Fe-P-B through reaction of FeCl,, NaH,P02 and KBH, in aqueous solution [4]. Since P and Et have different electron afEn@, the coexistence of the bi-metalloid elements iu the amorphous alloy may extend the possibility to regulate the powder properties. Obviously, it is worthwhile to study the preparation process a sd thereby the preparation mechanism, and to regulate the compositions in a wider range. In the present work, Fe,,-,-,P,B, U&P with 3.6 1x5 10.5 and 6.6 ly I 32.0 were systemaktlly produced and investigated. 5.40 g FeCl, - 6H,O and 4.24 g NaH,PO, +H,O were first dissolved in water separately then mixed. The pH of the mixture was regulated by adding NaOH solution. Finally, the volume of the mixture with definite pH was kept in 100 ml. Each sample was prepared by adding 100 ml 1 mol. L-’ KBH, solution into the above mixture (series A) or vice versa (series B) within 10 minutes under ultrasonic agitation. The detailed procedure was similar to that reported elsewhere [4]. Thermal treatments were performed at given temperatures below 700°C for 2 h in flowing H, with the rate of 60 mI - mitt-‘. The compositions were analyzed by an inductively coupled plasma method (ICP), X-ray diffraction (XRD) measurements were performed by using FeKa radiation. All isomer shit% of the MBssbauer spectra are given relative to a-iron. Differential scanning calorimetric (DSC) experiments was carried out in pure argon with a heating rate of 20 K * mitt-‘. The morphology and particle sixes were observed by the transmission electron microscopy 0W+vf). During preparation, it is found that Fe’+ reacted with H,PO; and formed Fe(H,PO,), co!loid which reacted
* Corresponding author. Fax: +86-25-3317761.
with KBH4 in the solution. The mu ment in liquid phase resulted in
was increased by adding NaOH
increases with pH, which is carsed by the decreasing of reaction rate in higher pH [5]. It can be seen that H
Tabk I tntlueace of pH vatue on cotnposition, mean particle average hyperfine field (HI Composition Sample pH d blul) Al 1.5 200 Wcd’,o.s B,, A2 2.5 F%.oP,.ohs.o 3@J A3 3.5 haJW329.1. * A4 5 hs&aBzw 6Qfl 1.5 Bl %d’wBm 130 B2 2.5 Fen,kd%2 o 23 B3 35 360 %dW~.o 470 84 5 Fe64.3P3.7B32.0
0304-8853/95/$09.50 Q 1995 Elsevier Scieze B.V. All rights reserved SSDI 0304-8853(94)01517-l
size (d) Ii m 23.3 22.2 18.7 19.0 22.2 19.7 19.9 t9.9
hyperlirrefield
total metalloid content(P + B)
trk profiki of series B (b).
Fe-P-B
2b-B2). Accordmgly,it is suggestedthatthereis a stronger bonding tendencybetweenFe and P than betweenFe and B, i.e., the preferentialbonding of Fed-Pto Fe-B *bondin Fe-P-B samples.Basedon this suggestion,it is reasonable to argue that the crystallization products will be mainly composedof cr-Feand Fe-P compoundsfor highP-contentsamples,while there will still be some Fe-l3 compoundsformed during crystallizationfor low-P-contentsamples.In order to prove this opinion, thecrystallization of Fe,P,B, sample was investigated.From XRD patterns,it is seenthatwhen annealingtemperature(T,) is lower than 3OO“C,the intensity of the halo peak around 28 = 57” increasesgradually with TA’This indicated that structuralrelaxation occurred,which induced the ordering of the atomic arrangements.When 3@ls TA2 35OT, the samplebeganto crystallizeand a characteristicsharppeak correspondingto cy-Fe(ll0) diffraction and a tracepeakto Fe$‘(lll) appeared.The continuousrising of TA resulted in full crystallization.At TA= SWC, severalcharacteristic diflkxtion peaks for Fe,P compound appeared.The annealing at TA= 6OO’Ccausedthe sintering and growth of cr-Femicrocrystakas determinedby the obvious decrease of full width at half maximumfor (110) diffraction peak from 0.5” at TA= SOOT to 0.3” at T, = 6130°C.Further annealingat TA= 700°Cdid not bring aboutvisible change in XRD pattern.This processwasconfirmedby Kssbauer experimentalresults.Anyway, it can be concluded that neither Fe,B, Fe,B nor other F&I speciesappeared during the annealingtreatment.However,for sampleA3, which was chosento investigatethe crystallizationof the low-P-content sample, Fe,B species with H= 23.8 T, IS=0.09mm~s-‘andQS=0.07mm~s-‘inM6ssbauer spectrumappearedafter annealingat 64O’C. In summary,Fe,,-,-,P,B, amorphouspowderswith 3.6 LX 5 10.5and 6.6 I y 5 32.0were systematicallyproducedand the experimentalresultssuggesteda preferential bonding of Fe-P to Fe-B bond. Acknowkfgqments:This work has been supportedby NNSFCand CPSF.
[l] J. van Wonterghem, S. Morup, S.W. Charles, S. Wells andJ. Villadsen, Phys. Rev. L&t. 55 (1985) 410. [2] J. van Wonterghem, S. Morup, C.I.W. Koch, S.W. Charles and S. W&s, Nature 322 (1986) 622. [3] S. Linderolh, Hyperfine Interactions 68 (1991) 107. [4] J. Shen, Z. Hu, Y. Hsiaand Y. Chen, Appl. Phys. L&t. 59 (1991) 3545. IS] S. Linderoth and S. Morup,J. Appl. Phys. 69 (1991) 5256.