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A simple one-step mechanically induced route was used for synthesis of Gd 2 MoO 6 (GMO). Single-phase with disordered structure was obtained after 12 ​h of milling. Elemental analysis revealed continuous decomposition of ammonium orthomolybdate. SEM-EDS (energy dispersive X-ray spectrometry) analysis confirmed a homogeneous distribution of Gd, Mo, and O with the atomic ratio 22.2:8.6:69.2% corresponding to Gd 1.998 Mo 0.774 O 6.228. Aside from conventional X-ray diffraction, we here paid an effort to obtain the information about the local structure of our GMO by 155Gd ​Mössbauer spectroscopy. The analysis of temperature dependence of magnetic susceptibility and field dependence of magnetization of GMO was confirmed to be similar to those of the mechano/thermally synthesized Gd 2 MoO 6 mentioned in our previous study (Tóthová et al., 2019) [1]. Small deviations suggest the presence of nonmagnetic unreacted materials in the starting mixture used in the present mechanosynthesis. We would like to emphasize that the present simplified synthesis without annealing steps leads to GMO with very good quality in the terms of magnetic properties. Mechanochemical reaction of milled mixture up to 12 ​h at 500 ​rpm. On the left: view on the grinding/milling chamber containing milled mixture together with grinding/milling balls. On the right: 155Gd ​Mössbauer spectrum of mechanosynthesized product, i.e. Gd 2 MoO 6. [Display omitted] • Preparation of nanocrystalline Gd 2 MoO 6 by one-step mechanosynthesis. • 155Gd ​Mössbauer spectra of mechanosynthesized product. • Analyzing the quality of mechanosynthesized material by magnetic measurements. [ABSTRACT FROM AUTHOR]

Two kinds of inorganic gadolinium(III)-hydroxy 'ladders', [2× n] and [3× n], were successfully trapped in succinate (suc) coordination polymers, [Gd2(OH)2(suc)2(H2O)] n ⋅ 2 n H2O ( 1) and [Gd6(OH)8(suc)5(H2O)2] n ⋅4 n H2O ( 2), respectively. Such coordination polymers could be regarded as alternating inorganic-organic hybrid materials with relatively high density. Magnetic and heat capacity studies reveal a large cryogenic magnetocaloric effect (MCE) in both compounds, namely (Δ H=70 kG) 42.8 J kg−1 K−1 for complex 1 and 48.0 J kg−1 K−1 for complex 2. The effect of the high density is evident, which gives very large volumetric MCEs up to 120 and 144 mJ cm−3 K−1 for complexes 1 and 2, respectively. [ABSTRACT FROM AUTHOR]

Magnetic properties of three variants of MOF-76(Gd), {[Gd(BTC)(H2O)]·G}n (BTC = benzene-1,3,5-tricarboxylate, G = guest molecules) were investigated by static susceptibility, isothermal magnetization and specific heat capacity measurements. In the study we used as synthesized MOF-76(Gd)-DMF (1) (G = DMF = dimethylformamide), containing DMF molecules in the cavity system, compound MOF-76(Gd) (2), activated complex without solvents in the cavities and water exchanged sample MOF-76(Gd)-H2O (3). A pronounced change in the magnetic entropy was found near the critical temperature for all three compounds. It was shown, that magnetic entropy change depends on the solvatation of the MOF. The highest value entropy change, ΔSMpk(T) was observed for compound 2 (ΔSMpk(T) = 42 J kg−1 K−1 at 1.8 K for ΔH = 5 T). The ΔSMpk(T) for the compounds 1, 2 and 3 reached 81.8, 88.4 and 100% of the theoretical values, respectively. This suggests that in compound 3 Gd3+···Gd3+ antiferromagnetic interactions are decoupled gradually, and higher fields promote a larger decoupling between the individual spin centers. The observed entropy changes of compounds were comparable with other magnetic refrigerants proposed for low-temperature applications. To study the magnetothermal effect of 2 (the sample with largest −ΔSMpk), the temperature-dependent heat capacities (C) at different fields were measured. The value of magnetic entropy S obtained from heat capacities (39.5 J kg−1 K−1 at 1.8 K for an applied magnetic field change of 5 T) was in good agreement with that derived from the magnetization data (42 J kg−1 K−1 at 1.8 K). [ABSTRACT FROM AUTHOR]