Magnetocaloric effect of high-spin cluster with Ni9W6 core.

A study of magnetocaloric effect of a structurally unique molecular magnet built of spin clusters with the pentadecanuclear Ni(II) 9 W(V) 6 core forming a cube-like framework is reported. The compound crystallizes in the triclinic system. The clusters display anisotropy quantified with the axial D =0.07 K and rhombic E =0.023 K anisotropy constants. The temperature dependences of magnetic entropy change Δ S M as well as the adiabatic temperature change Δ T ad due to applied field change μ 0 Δ H ranging from 1 to 9 T have been determined by employing the relaxation calorimetry measurements in applied field. The maximum value of Δ S M for μ 0 Δ H =5 T is 18.38 J K −1 mol −1 (3.36 J K −1 kg −1 ) at 4.3 K. The corresponding maximum value of Δ T ad =4.6 K is attained at 2.2 K. The occurrence of the inverse MCE has been observed at high temperatures for small field change values. The temperature dependence of the exponent n characterizing the field dependence of Δ S M has been estimated and discussed. The study revealed that the compound may be treated as a possible candidate for cryogenic magnetic cooling. [ABSTRACT FROM AUTHOR]