Gd2Cu(SO4)2(OH)4: a 3d-4f hydroxysulfate with an enhanced cryogenic magnetocaloric effect

Reversible single-crystal-to-single-crystal transition in Gd(III) metal-organic frameworks induced by heat and solvents with a significant magnetocaloric effect

The design and synthesis of a Gd(III) metal-organic framework with the formula [Gd4(BTDI)3(DMF)4]n (JXUST-40, H4BTDI = 5,5'-(benzo[c][1,2,5]thiadiazole-4,7-diyl)diisophthalic acid) are reported hererin. Interestingly, a reversible single-crystal-to-single-crystal transition between JXUST-40 and {[Gd4(BTDI)3(H2O)4]·6H2O}n (JXUST-40a) was achieved under the stimulation of heat and solvents. Both JXUST-40 and JXUST-40a exhibited good stability when soaked in common solvents and aqueous solutions with pH values of 1-12. Magnetic studies showed that JXUST-40a has a larger magnetocaloric effect with -ΔSmaxm = 26.65 J kg-1 K-1 at 2 K and 7 T than JXUST-40 due to its larger magnetic density. Structural analyses indicated that the coordinated solvent molecules play a crucial role in the coordination environment around the Gd(III) ions and the change in the framework, ultimately leading to the changes in the pore size and magnetism between JXUST-40 and JXUST-40a. In addition, both isomorphic [Dy4(BTDI)3(DMF)4]n (JXUST-41) and {[Dy4(BTDI)3(H2O)4]·6H2O}n (JXUST-41a) displayed slow magnetic relaxation behaviour.

Structure, magnetism and magnetocaloric effect in a new triangular lattice compound Gd3Cu9(OH)19Br8

A new triangular lattice compound Gd₃Cu₉(OH)₁₉Br₈ has been synthesized by the hydrothermal method. The structure, magnetism and magnetocaloric effect of Gd₃Cu₉(OH)₁₉Br₈ have been studied by X-ray diffraction, magnetic susceptibility, isothermal magnetization and specific heat measurements. In Gd₃Cu₉(OH)₁₉Br₈, the Cu²⁺ ions form a Kagome lattice along the ab plane, and Gd³⁺ ions are located in the center of hexagonal holes of the Kagome layer. The Cu-sublattice and Gd-sublattice overlap and constitute a magnetic triangular lattice. The temperature dependence of susceptibility and specific heat curves indicate no magnetic transition down to 2 K, suggesting a paramagnetic-like behavior at low temperature. The magnetocaloric effect (MCE) at low temperature has been calculated according to Maxwell's equations. The maximum value of magnetic entropy change −ΔS_M is 26.04 J kg⁻¹ K⁻¹ and adiabatic temperature change ΔT_ad is 13.79 K, for a field change of 0–7 T, indicating a potential application of this compound in the field of magnetic refrigeration at low temperature. The influence of 4f–3d interaction on magnetism and MCE is also discussed.

The two-dimensional magnetic lattice of Gd₃Cu₉(OH)₁₉Br₈, where Gd³⁺ ions are located in the center of hexagonal holes of the Cu-Kagome lattice.

A new {Cu3-Gd2} cluster as two-in-one functional material with unique topology acting as a refrigerant as well as adsorbent for cationic dye

A new heterometallic cluster system, [Cu3Gd2(H3btp)2(OAc)6]3H2O {Cu3-Gd2} is designed by employing 1,3-Bis(tris(hydroxymethyl)methylamino)propane (H6btp) as a ligand. The cluster is characterized by FTIR, TGA, PXRD, SCXRD and topological analyses. The crystallography...

Gd(III)-based metal-organic frameworks and coordination polymers for magnetic refrigeration

As the alternatives of expensive and increasingly shortage 3He for ultralow-temperaturerefrigeration, molecule-based magnetorefrigerant materials have attracted much attention in the past decades. Among them, Gd(III)-based metal-organic frameworks and coordination polymers...

Large Magnetocaloric Effect in Li3K9Gd3(BO3)7 Crystal Featuring Sandwich-Like Three-Dimensional Framework

A new Gd-based borate crystal, Li₃K₉Gd₃(BO₃)₇, has been successfully obtained via the high-temperature solution method using Li₂O-K₂O-B₂O₃ self-flux. It crystallizes in monoclinic space group P2/n (no. 10) with lattice parameters a = 11.3454(6) Å, b = 9.9881(4) Å, c = 11.4467(7) Å, α = γ = 90 ^o, β = 114.782(7) ^o, and Z = 2. Li₃K₉Gd₃(BO₃)₇ exhibits an intriguing sandwich-like three-dimensional (3D) framework constructed from [Gd-B-O]_∞ layers, KO_n (n = 6 and 8) polyhedra, and LiO₄ tetrahedra, in which [Gd-B-O]_∞ layers are built from two types of GdO₈ polyhedra and triangular BO₃ units. Magnetic measurements showed that Li₃K₉Gd₃(BO₃)₇ exhibits a large magnetocaloric effect with -ΔS_m = 39.3 J kg^-1 K^-1 at 2.0 K for ΔH = 7 T, which is slightly higher than that of the commercial gadolinium gallium garnet under the same conditions. The powder X-ray diffraction, infrared spectrum, and UV-vis-NIR diffuse reflectance spectrum were also performed to characterize Li₃K₉Gd₃(BO₃)₇. The electronic band structures, partial density of states, and refractive indices of Li₃K₉Gd₃(BO₃)₇ were investigated via the first-principle calculations.

Structural Complexity and Magnetic Orderings in a Large Family of 3d-4f Heterobimetallic Sulfates

The synthesis of a large family of heterobimetallic lanthanide copper sulfates was realized via stoichiometric hydrothermal reactions among Ln₂O₃, CuO, and H₂SO₄, giving rise to four distinct phases, namely Ln₂Cu(SO₄)₂(OH)₄ (Ln = Sm-Ho) (LnCuSO₄-1), Ln₄Cu(SO₄)₂(OH)₁₀ (Ln = Tm-Lu) (LnCuSO₄-2), LnCu(SO₄)(OH)₃ (Ln = Nd-Gd, except Pm) (LnCuSO₄-3), and LnCu(SO₄)(OH)₃ (Ln = Dy-Lu) (LnCuSO₄-4), with completely different topologies. The passage from LnCuSO₄-1 and LnCuSO₄-3 to LnCuSO₄-2 and LnCuSO₄-4 across the 4f series, respectively, can be ascribed to the effect of lanthanide contraction, which progressively induces shrinking of the Ln-O distance, reduction in the Ln coordination number, and eventually structural transitions. The incorporation of identical 3d-4f metal ions into different spin-lattices, in conjunction with substitution of diverse Ln³⁺ cations within the same spin-lattice, gives rise to tunable magnetic properties varying from ferromagnetic ordering in GdCuSO₄-3 and HoCuSO₄-4 to antiferromagnetic ordering in YbCuSO₄-4, and to paramagnetic correlations found in GdCuSO₄-1 and YbCuSO₄-2.

A new approach to fabricate the Mn(ii)-based magnetic refrigerant through incorporation of a diamagnetic {LiO4} spacer

A new 3D MOF [MnLi₂(ip)₂(H₂O)₂] (1) with a 1D heterometallic inorganic Mn(ii)-Li(i) chain is reported. With the assistance of diamagnetic {LiO₄} connectors, which separate the paramagnetic Mn(ii) ions and act as magnetic spacers, very weak magnetic interactions were obtained. Remarkably, 1 showed a significant magnetocaloric effect (MCE) with a large entropy change value of 30.4 J kg^-1 K^-1 for ΔH = 8 T at 2 K.

A novel alb metalloring organic framework with a {Ni12Gd24} cage exhibiting a significant magnetocaloric effect

With the aid of a bifunctional 6-mercaptonicotinic acid ligand, a novel {Ni₁₂Gd₂₄} cage-based (6, 12)-c alb-MROF that is assembled from a {Gd₄(OH)₄(COO)₆} trigonal-prism building unit and a {Ni₆S₁₂} hexagonal-prism molecular building block has been synthesized for the first time. It exhibits a large MCE value of 29.86 J kg^-1 K^-1 for ΔH = 8 T at 2 K.

Coordination-Cluster-Based Molecular Magnetic Refrigerants

Coordination polymers serving as molecular magnetic refrigerants have been attracting great interest. In particular, coordination cluster compounds that demonstrate their apparent advantages on cryogenic magnetic refrigerants have attracted more attention in the last five years. Herein, we mainly focus on depicting aspects of syntheses, structures, and magnetothermal properties of coordination clusters that serve as magnetic refrigerants on account of the magnetocaloric effect. The documented molecular magnetic refrigerants are classified into two primary categories according to the types of metal centers, namely, homo- and heterometallic clusters. Every section is further divided into several subgroups based on the metal nuclearity and their dimensionalities, including discrete molecular clusters and those with extended structures constructed from molecular clusters. The objective is to present a rough overview of recent progress in coordination-cluster-based molecular magnetic refrigerants and provide a tutorial for researchers who are interested in the field.