Mn2þ-induced room-temperature ferromagnetism and spin-glass behavior in hydrothermally grown Mn-doped ZnO nanorods

The magnetic properties of Mn-doped ZnO (ZnO:Mn) nanorods grown by hydrothermal process at a temperature of 200 8C and a growth time of 3 h have been studied. The samples were characterized by using powder X-ray diffraction with Rietveld refinement, scanning electron microscopy, energy-dispersive X-ray analysis and SQUID magnetometry. Mn (3 wt%) and (5 wt%)-doped ZnO samples exhibit paramagnetic and ferromagnetic behavior, respectively, at room temperature. The spin-glass behavior is observed from the samples with respect to the decrease of temperature. At 10 K, both samples exhibit a hysteresis loop with relatively low coercivity. The room-temperature ferromagnetism in 5 wt% Mn-doped ZnO nanorods is attributed to the increase in the specific area of grain boundaries, interaction between dopant Mn2þ ions substituted at Zn2þ site and the interaction between Mn2þ ions and Zn2þ ions from the ZnO host lattice

Mn(II) complexes of some acylhydrazones with NNO donor sites: Syntheses, a spectroscopic view on their coordination possibilities and crystal structures

Mn(II) complexes derived from a set of acylhydrazones were synthesised and characterized by elemental analyzes, IR, UV–vis and X-band EPR spectral studies as well as conductivity and magnetic susceptibility measurements. In the reported complexes, the hydrazones exist either in the keto or enolate form, as evidenced by IR spectral data. Crystal structures of two complexes are well established using single crystal X-ray diffraction studies. In both of these complexes two equivalent monoanionic ligands are coordinated in a meridional fashion using cis pyridyl, trans azomethine nitrogen and cis enolate oxygen atoms positioned very nearly perpendicular to each other. EPR spectra in DMF solutions at 77 K show hyperfine sextets and in some of the complexes the low intensity forbidden lines lying between each of the two hyperfine lines are also observed