Cristallite size tuning on magnetocaloric effect of ball milled HoAl2
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2016
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BRAZILIAN MRS MEETING, 15th
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The magnetocaloric effect (MCE) is the basis for alternative, environment-friendly
new refrigeration technologies. It is an intrinsic property of all magnetic
materials, occurring as a consequence of the coupling among external applied
field and the magnetic sub-lattice. [1] In this study, we report on the synthesis,
microstructural and magnetic characterization of mechanically milled HoAl2
compound. The samples were investigated by using x-ray diffraction, scanning
electron microscopy (SEM) and magnetization measurements. HoAl2
polycrystalline sample were submitted to a milling process using high energy ball
mill in order to produce metallic nanoparticles. The bulk sample show single
phase with cubic MgCu2- type structure. The lattice parameter was not significant
changed by milling process up to 20 h of milling time. On the other hand, the
crystallite size is strongly reduced reaching 28 nm for 20 h sample. Magnetic
measurement show ferromagnetic phase transition around 32 K for bulk and all
milled samples. A contribution related with spin reorientation is also observed
below 20K, which becomes more pronounced as milling time increase. The
magnetization of saturation reduces from 8.4 (bulk sample) to 6.2 μB/u.f. (20 h
sample), due to the weakening of long-range magnetic ordering caused by size
effects. The mechanical milling reduces the maximum values of magnetic entropy
change (−DSM
max) from 30 J/kgK (bulk sample) to 15 J/kgK (20 h milled sample). A
significant broadening in the −DSM peak profile is observed as the milling time
increase, which enhance in the full width half maximum (δTFWHM) of entropy
change peak. High values of δTFWHM are associated with a large operation
temperature range of magnetic refrigerator prototypes making the milled HoAl2
interesting for magnetic refrigeration purposes.
Como referenciar
PAULA, VINICIUS G. de; REIS, DELCICLEIDE C. dos; SILVA, LUZELI M. da; SANTOS, ADENILSON O. dos; CARVALHO, ROSSANO L.; OTUBO, LARISSA; COELHO, ADELINO de A.; CARDOSO, LISANDRO. Cristallite size tuning on magnetocaloric effect of ball milled HoAl2. In: BRAZILIAN MRS MEETING, 15th, September 25-29, 2016, Campinas, SP. Abstract... São Carlos, SP: Aptor Software, 2016. p. 1543-1544. Disponível em: http://repositorio.ipen.br/handle/123456789/28069. Acesso em: 20 Mar 2026.
Esta referência é gerada automaticamente de acordo com as normas do estilo IPEN/SP (ABNT NBR 6023) e recomenda-se uma verificação final e ajustes caso necessário.