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The influence of 1.9 MeV proton irradiation on structural and magnetic properties has been explored in the two-dimensional (2D) NiSO4(1,3-phenylenediamine)2 coordination ferrimagnet. The X-ray powder diffraction and IR spectroscopy revealed that the octahedrons with Ni ion in the center remain unchanged regardless of the fluence a sample received. In contrast, proton irradiation greatly influences the hydrogen bonds in the flexible parts in which the 1,3-phenylenediamine is involved. Dc magnetic measurements revealed that several magnetic properties were modified with proton irradiation. The isothermal magnetization measured at T = 2.0 K varied with the proton dose, achieving a 50% increase in magnetization in the highest measured field µ0Hdc = 7 T or a 25% decrease in remanence. The most significant change was observed for the coercive field, which was reduced by 90% compared to the non-irradiated sample. The observed results are accounted for the increased freedom of magnetic moments rotation and the modification of intralayer exchange couplings. [ABSTRACT FROM AUTHOR]

A new family of hybrid organic–inorganic layered materials based on nickel sulfates was synthesized using a simple, solvent-free synthesis approach using 1,2-phenylenediamine (OPD), 1,3-phenylenediamine (MPD), and 1,4-phenylenediamine (PPD) as organic templates and ligands. Diamines act as structure-directing agents to obtain 1D [Ni(OPD)2SO4] (1), 2D [Ni(MPD)2SO4] (2) and 3D [Ni(PPD)SO4] (3) frameworks. The crystal structures of 1–3 were determined using data from X-ray powder diffraction (XRPD) measurements and represent I2/a, Cc, and Cmcm space groups, respectively. The compounds display different dimensionalities of the frameworks; however, the magnetic studies reveal transitions to 3D magnetic long-range ordered phases in all three cases below 23 K (1), 25 K (2) and 25 K (3). The observed ordering in all compounds is a consequence of significant interchain (1) and intralayer (2 and 3) interactions which lead to considerable spin–spin correlations, which are strong enough to couple the adjacent layers. In addition, in all three compounds, there is a competition between ferromagnetic and antiferromagnetic interactions in which the latter ones successively get stronger with the substitution of dipolar couplings by superexchange ones. [ABSTRACT FROM AUTHOR]

A novel one-dimensional CoII coordination polymer (OPD)2CoIISO4 was formed from alternating tetrahedral sulphate anions, Co centers and molecules of 1,2-phenylenediamine (OPD). The thermal stability of the structure was confirmed up to ∼230 °C using thermogravimetry and non-ambient powder X-ray diffraction in air. The distorted pseudo-octahedral coordination sphere of CoII ions promotes strong magnetic anisotropy. Therefore (OPD)2CoIISO4 was subjected to thorough characterization with ab initio and DFT calculations along with dc magnetic measurements both of which point to strong easy-axis anisotropy (D/kB≈−87 K, E/kB≈ 23 K). The analysis of ac susceptibility revealed field assisted magnetic relaxation in two field regimes: a low field one with one relaxation time and a high field one where three relaxation times were distinguished. The main role in relaxations of the fastest process (τ1) was attributed to the direct and Raman processes. [ABSTRACT FROM AUTHOR]