Giant Reversible Magnetocaloric Effect in Flower-like b-Co(OH)2 Hierarchical Superstructures Self-assembled by Nanosheets

A facile hydrothermal strategy is proposed to synthesize flower-like β-Co(OH)2 hierarchical microspherical superstructures with a diameter of 0.5-1.5 μm, which are self-assembled by β-Co(OH)2 nanosheets with the average thickness ranging between 20 and 40 nm. The magnetocaloric effect associated with magnetic phase transitions in Co(OH)2 superstructures has been investigated. A sign change in the magnetocaloric effect is induced by a magnetic field, which is related to a filed-induced transition from the antiferromagnetic to the ferromagnetic state below the Neel temperature. The large reversible magnetic-entropy change -ΔSm (13.4 J/kg K at 15 K for a field change of 5 T) indicates that flower-like Co(OH)2 superstructures is a potential candidate for application in magnetic refrigeration in the low-temperature range.

[1]  K. G. Sandeman.  Magnetocaloric materials: The search for new systems , 2012, 1201.3113.

[2]  B. Li,et al.  Magnetic properties of Dy nanoparticles and Al2O3-coated Dy nanocapsules , 2011 .

[3]  X. G. Liu,et al.  Magnetic properties and large cryogenic low-field magnetocaloric effect of HoCo2 nanoparticles without core/shell structure , 2010 .

[4]  S. Dou,et al.  A sign of field-induced first order magnetic state transition and giant reversible magnetocaloric effect in cobalt hydroxide nanosheets , 2010 .

[5]  X. G. Liu,et al.  Microstructure and magnetic properties of graphite-coated Gd nanocapsules , 2009 .

[6]  X. G. Liu,et al.  Formation and large cryogenic magnetocaloric effect of HoAl2/Al2O3 nanocapsules , 2009 .

[7]  Wei Liu,et al.  Giant reversible magnetocaloric effect in cobalt hydroxide nanoparticles , 2008 .

[8]  Zhidong Zhang,et al.  The large cryogenic magnetocaloric effect of TbAl2 nanocapsules , 2008 .

[9]  Zhidong Zhang,et al.  Giant magnetocaloric effect in the Ising antiferromagnet DySb , 2008 .

[10]  T. Samanta,et al.  Giant magnetocaloric effect in antiferromagnetic ErRu2Si2 compound , 2007 .

[11]  Zhidong Zhang,et al.  Giant magnetocaloric effect in ε-(Mn0.83Fe0.17)3.25Ge antiferromagnet , 2007 .

[12]  X. Moya,et al.  Inverse magnetocaloric effect in ferromagnetic Ni–Mn–Sn alloys , 2005, Nature materials.

[13]  Junqing Hu,et al.  Two-dimensional micrometer-sized single-crystalline ZnO thin nanosheets , 2003 .

[14]  Y. Bandō,et al.  The Magnetic Property of β-Co(OH)2 , 1966 .