Influence of Co addition on the magnetocaloric effect of FeCoSiAlGaPCB amorphous alloys

In luence o Co addi ion on he magne ocalo ic e ec o FeCoSiAlGaPCB amo phous alloys V. F anco, J. M. Bo ego, and A. Conde Dp o. Física de la Ma e ia Condensada, ICMSE-CSIC, Uni e sidad de Se illa, P.O. Box 1065, 41080 Se illa, Spain S. Ro h Leibniz Ins i u ü Me allische We ks o e, IFW D esden, Pos ach 270016, D 01171 D esden, Ge many 共Recei ed 9 Janua y 2006; accep ed 22 Feb ua y 2006; published online 28 Ma ch 2006兲 The FeCoSiAlGaPCB alloys can be p epa ed as bulk amo phous ma e ials, wi h ou s anding mechanical p ope ies and inc eased elec ical esis i i y. These ea u es can be bene icial o hei applica ion as a magne ic e ige an . The in luence o Co addi ion on he magne ic en opy change o he alloy has been s udied. This composi ional modi ica ion displaces he empe a u e o he peak en opy change close o oom empe a u e, bu educes he e ige an capaci y o he ma e ial. Fo he Co- ee alloy, he peak en opy change is inc eased wi h espec o a Fineme alloy con aining Mo, bu i s e ige an capaci y is no enhanced. © 2006 Ame ican Ins i u e o Physics. 关DOI: 10.1063/1.2188385兴 Magne ic e ige a ion is a ield o esea ch ha has gained inc easing a en ion, as i is conside ed an al e na i e o he gas comp ession-expansion cycle. A empe a u es close o oom empe a u e, a e-ea h-based ma e ials a e among he mos ele an ones.1–4 To display a big magne o- calo ic esponse, wo equi emen s ha e o be ul illed: he ma e ial needs o exhibi a big magne ic momen and, also, a s ong empe a u e dependence o magne iza ion close o he wo king empe a u e. This second condi ion, ela ed o a magne ic phase ansi ion, can be achie ed in wo di e en ways. Ei he by a i s -o de phase ansi ion, which p oduces an ab up empe a u e change o he magne ic momen and, he e o e, a ema kable peak in he magne ic en opy change 共⌬SM兲a he ansi ion empe a u e, o by a second o de phase ansi ion, which causes a mo e smea ed peak in ⌬SM. Howe e , he ema kable hys e esis ha appea s in some ma- e ials, associa ed o i s o de phase ansi ions, may educe he ac ual e iciency o he cooling p ocess.5I has been poin ed ou , ne e heless, ha in o de o compa e he cha - ac e is ics o di e en ma e ials as candida es o magne ic e ige an s, hei e ige an capaci y 共RC兲in a e e sible cycle, connec ed o he en opy abso bed by he e ige an a he cold end o he cycle and i s empe a u e span, should be used.6 The sea ch o low-cos ma e ials o high- empe a u e magne ic e ige a ion is a ield o cu en in e es .7–12 Re- cen ly i has been shown ha some so -magne ic amo phous alloys a e good candida es o his applica ion,11 wi h a e- ige an capaci y ha is compa able o ha o low-hys e e ic Gd-based ma e ials.4I has also been shown ha he nanoc- ys alliza ion o he alloy, al hough b oadening he ⌬SM peak, does no imp o e he RC o he ma e ial. Besides he peak en opy change, RC and ma e ial cos , he e a e o he ac o s ha should be aken in o accoun o a ma e ial o be e icien ly applied,12 such as mechanical p ope ies, co o- sion esis ance, elec ical esis i i y, e c. Mul icomponen Fe-based bulk amo phous alloys, o- ge he wi h hei p omising magne ic p ope ies,13,14 p esen ou s anding mechanical p ope ies.13,15 Pieces o applica ion de ices, wi h he inal equi ed shape, could be p epa ed by mold cas ing. Fo he Fe–共Al, Ga兲–共P, C, B, Si兲alloy se ies, cylinde s wi h up o 3 mm in diame e ha e been ob ained.13 Mo eo e , he high elec ical esis i i y associa ed o he nonc ys alline cha ac e o he alloys is a bene icial ea u e o hei applica ion as e ige an ma e ials. Howe e , he e a e ew s udies conce ning he magne ocalo ic esponse o bulk amo phous alloys.16 I has been shown ha he Co ad- di ion o his amily o alloys p oduces a dec ease o i s Cu ie empe a u e, TC am.14 The e o e, his composi ional change could be a way o uning he ⌬SMpeak empe a u e. In his wo k he magne ic en opy change o he FeCoSiAl- GaPCB se ies is cha ac e ized, analyzing he in luence o Co addi ion on he e ige an capaci y o he ma e ial. Amo phous ibbons, ⬃25 ␮ m hick and ⬃10 mm wide, wi h nominal composi ion 共FexCoyBzCu兲Si3Al5Ga2P10 共Table I兲we e p epa ed by single- olle mel spinning. The amo - phous cha ac e o he as-quenched alloys was checked by x- ay di ac ion. P e iously o he measu emen s, samples we e s ess elaxed by he mal annealing in an A a mo- sphe e a 675 K o 30 min. The ield dependence o magne- iza ion was measu ed in a Lakesho e 7407 Vib a ing Sample Magne ome e using a maximum applied ield H=15 kOe wi h ield s eps o 50 Oe, o cons an empe a u es in he ange 300–720 K in inc emen s o 10 K. The magne ic en- opy change due o he applica ion o a magne ic ield Hhas been calcula ed om he nume ical app oxima ion o he equa ion TABLE I. Composi ion o he s udied 共FexCoyBzCu兲Si3Al5Ga2P10 alloys. Alloy A B C D E F x70 56 43 29 17 5 y01426405263 z5 6 8 9 10 12 u543210 APPLIED PHYSICS LETTERS 88, 132509 共2006兲 0003-6951/2006/88共13兲/132509/3/$23.00 © 2006 Ame ican Ins i u e o Physics88, 132509-1 This a icle is copy igh ed as indica ed in he a icle. Reuse o AIP con en is subjec o he e ms a : h p://sci a ion.aip.o g/ e mscondi ions. Downloaded o IP: 150.214.230.47 On: Mon, 30 No 2015 13:03:39 ⌬SM= 冕 0 H 冉 ⳵ M ⳵ T 冊 H dH,共1兲 whe e he pa ial de i a i e is eplaced by ini e di e ences and he in eg a ion is pe o med nume ically. Figu e 1 shows he empe a u e dependence o he mag- ne ic en opy change co esponding o an applied ield H =15 kOe o he di e en s udied samples. The e is a e- ma kable co ela ion be ween he ⌬SMpeak empe a u es 共Tpk兲o each sample and i s co esponding TC am calcula ed by he “kink poin ” me hod 共Fig. 2兲. Al hough Tpk is shi ed o empe a u es close o oom empe a u e as he Co con en in he alloy inc eases, he magni ude o he peak 共兩⌬SM pk兩兲 con- inuously dec eases wi h inc easing Co con en 共Fig. 2兲. This composi ional dependence o 兩⌬SM pk兩is in ag eemen wi h he con inuous dec ease o he magne ic momen pe ansi ion me al a om as Co con en inc eases in his se ies o alloys.14 The RC o he samples has been calcula ed by he Wood and Po e me hod6共⌬SM⌬Tin Fig. 3兲, ei he using he op- imal cycle empe a u es o imposing oom empe a u e as he empe a u e o he cold ese oi 共 he cold and ho ese - oi empe a u es, Tcand Th, a e plo ed in Fig. 4 in bo h cases兲. To allow he compa ison wi h published da a o o he ma e ials, he p oduc o he peak en opy change imes he ull wid h a hal maximum o he peak 共⌬SM pk ⌬TFWHM in Fig. 3兲, and he a ea unde he ⌬SM共T兲cu es using he empe a u es a hal -maximum o he peak as he in eg a ion limi s 共A ea in Fig. 3兲ha e also been calcula ed. Fo he sample wi h he lowes Fe con en , he RC o he op imal cycle could no be calcula ed, as he peak is oo close o oom empe a u e and Tc共op imal兲is below he a ailable expe imen al ange. As he Co con en inc eases, he RC o he samples dec eases. The mino di e ences in ⌬SM⌬T o he op imal cycle and o ha wi h Tca oom empe a u e e idence ha he bes pe o mance o hese ma e ials is achie ed o a cold ese oi close o oom empe a u e. Fig- u e 4 shows he empe a u es o he op imal cycles and hose o he cycles wi h Tca oom empe a u e. While Thdisplays no big di e ences be ween bo h cycles, Tc共op imal兲p esen s a mo e sca e ed cha ac e . This is ela ed o he ac ha he low- empe a u e pa o he ⌬SM共Fig. 1兲has a smalle em- pe a u e dependence and a mino change in he ⌬SM alue co esponding o he selec ed empe a u es o he cycles im- plies a ele an change in he associa ed empe a u e. As Co con en inc eases, he empe a u e span o he cycles is educed. Al hough he Co addi ion in he FeCoSiAlGaPCB alloy se ies can be used o ine une TC am and, consequen ly, Tpk,i dec eases bo h 兩⌬SM pk兩and he RC o he ma e ial. The Co- ee alloy p esen s a RC compa able o ha o a Mo-Fineme alloy wi h a simila Fe con en ,11 al hough 兩⌬SM pk兩and he empe a u e span a e bigge in he p esen case. FIG. 1. 共Colo online兲Tempe a u e dependence o he magne ic en opy change o he di e en s udied alloys. Lines a e a guide o he eye. FIG. 2. 共Colo online兲Composi ional dependence o he Cu ie empe a u e o he alloys, he peak en opy change empe a u e, and he maximum mag- ne ic en opy change. Lines a e a guide o he eye. FIG. 3. 共Colo online兲Composi ional dependence o he e ige an capaci y 共RC兲calcula ed by h ee di e en me hods 共 o he Wood and Po e me hod, RC has been calcula ed o he op imal e e sible e ige a ion cycle and o cycles depa ing om oom empe a u e兲. Lines a e a guide o he eye. FIG. 4. 共Colo online兲Composi ional dependence o he empe a u es o he cold and ho ese oi s o he op imal cycles 共solid symbols兲and o cycles depa ing om oom empe a u e 共open symbols兲. Lines a e a guide o he eye. 132509-2 F anco e al. Appl. Phys. Le . 88, 132509 共2006兲 This a icle is copy igh ed as indica ed in he a icle. Reuse o AIP con en is subjec o he e ms a : h p://sci a ion.aip.o g/ e mscondi ions. Downloaded o IP: 150.214.230.47 On: Mon, 30 No 2015 13:03:39 This wo k was suppo ed by he Spanish Go e nmen and EU-FEDER 共P ojec MAT 2004-04618兲and he PAI o Jun a de Andalucía. 1A. M. Tishin, in Handbook o Magne ic Ma e ials Vol. 12, edi ed by K. H. J. Buschow 共Else ie , Ams e dam, 1999兲, pp. 395–524. 2K. A. Gschneidne , J . and V. K. Pecha sky, Annu. Re . Ma e . Sci. 30, 387 共2000兲. 3V. K. Pecha sky and K. A. Gschneidne , J ., Phys. Re . Le . 78, 4494 共1997兲. 4V. P o enzano, A. J. Shapi o, and R. D. Shull, Na u e 429, 853 共2004兲. 5E. M. Le in, V. K. Pecha sky, and K. A. Gschneidne , J ., Phys. Re . B 62, R14625 共2000兲. 6M. E. Wood and W. H. Po e , C yogenics 25, 667 共1985兲. 7O. Tegus, E. B uck, K. H. J. Buschow, and F. R. de Boe , Na u e 415, 150 共2002兲. 8D. Wang, K. Peng, B. Gu, Z. Han, S. Tang, W. Qin, and Y. Du, J. Alloys Compd. 358, 312 共2003兲. 9I. Sko anek and J. Ko ac, Czech. J. Phys. 54, D189 共2004兲. 10S. A alay, H. Gence , and V. S. Kola , J. Non-C ys . Solids 351, 2373 共2005兲. 11V. F anco, J. S. Blázquez, C. F. Conde, and A. Conde, Appl. Phys. Le . 88, 042505 共2006兲. 12E. B ück, J. Phys. D 38, R381 共2005兲. 13A. Inoue, Ac a Ma e . 48, 279 共2000兲. 14J. M. Bo ego, A. Conde, S. Ro h, and J. Ecke , J. Appl. Phys. 92, 2073 共2002兲. 15W. L. Jonson, Ma e . Res. Bull. 24,42共1999兲. 16T. D. Shen, R. B. Schwa z, J. Y. Coul e , and J. D. Thompson, J. Appl. Phys. 91,5240共2002兲. 132509-3 F anco e al. Appl. Phys. Le . 88, 132509 共2006兲 This a icle is copy igh ed as indica ed in he a icle. Reuse o AIP con en is subjec o he e ms a : h p://sci a ion.aip.o g/ e mscondi ions. Downloaded o IP: 150.214.230.47 On: Mon, 30 No 2015 13:03:39