首页|Magneto-thermal and magnetization relaxation dynamics of a family of di-nuclear lanthanide complexes
Magneto-thermal and magnetization relaxation dynamics of a family of di-nuclear lanthanide complexes
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NSTL
Elsevier
The reaction of Ln(NO3)3.nH2O (where Ln = Gd, Tb, Dy or Yb) in the presence of sodium acetate led us to isolate a family of structurally analogous dinuclear lanthanide complexes with the general molecular formula of [Ln2(CH3COO)4(NO3)2(H2O)4]. 2H2O (where Ln = Gd (1) or Tb (2) or Dy (3) or Yb (4)), which are characterized by single-crystal X-ray diffraction. The dc magnetic susceptibility measurements were performed on 1 reveal the presence of a weak ferromagnetic exchange between the Gd(III) center (J = +0.01 cm- 1; -2JS1.S2 Hamiltonian). This weak exchange interaction in 1 is presumably overcome by the external magnetic field, and therefore, the Xband EPR spectral features of 1 were simulated by considering the single-ion spin Hamiltonian parameter (g = 1.98, D = 0.03 cm- 1, and divide E/D divide = 0.004). In contrast to 1, complexes 2-4 exhibit a weak antiferromagnetic exchange between the Ln(III) centers. The magnetization relaxation dynamics studies performed on the anisotropic complexes (2-4) show slow relaxation of magnetization in the presence of an optimum external magnetic field. The spin-lattice relaxation predominantly follows the Direct and Raman mechanism exclusively, and the Orbach process was found to be non-existent. By employing ab initio calculations, the electronic structure and the mechanism of magnetization relaxation dynamics of 2-4 have been investigated. The magnetocaloric effect parameter for 1 shows a change in magnetic entropy (-dSm) value of 39 J Kg-1 K-1 at 2.0 K (dH = 70 kOe), which is one of the largest -dSm value registered among the various discrete molecular coolants reported in the literature..
NSTL
Elsevier
