Comparison of the Crystalline Structure and Magnetic Properties in Coprecipitated CoFe2O4 and CoLa0.1Fe1.9O4

Comparison of the crystalline structure and magnetic properties in CoFe2O4 and CoLa0.1Fe1.9O4 nanoparticles have been studied. The obtained samples are characterized by using X-Ray Diffractometer (XRD), Fourier Transform InfraRed (FTIR) and Vibrating Sample Magnetometer (VSM). The XRD results show that the crystallite size of the samples are 24.539 nm and 28.772 nm for the CoFe2O4 and CoLa0.1Fe1.9O4 nano particles, respectively. Furthermore, the crystalline strain is 0.00460 and lightly decreases to 0.00392 with the presence of lanthanum. The different of the atomic radius for both Fe3+ (1.26 Å) and La3+ (1.87 Å) should attribute to the change of the crystalline strain. FTIR results show that the absorption peak of the CoFe2O4 occur at k = 591.21/cm and the CoLa0.1Fe1.9O4 is 594.10/cm. This indicate that the lanthanum cation successfully substitutes to the original bonding-structure of the CoFe2O4. VSM results show that the HC are 1.02 kOe and 0.705 kOe for the samples without and with La3+ cations. Moreover, the MS is equal 69.625 emu/g and decrease of 55.70 emu/g with the present of the La3+ cations. Finally, the strains-induce-magnetism should contribute to the changes of the MS that associated with changes in crystalline strains at the previous discussion.

Hexahalometallate salts of trivalent scandium, yttrium and lanthanum: cation–anion association in the solid state and in solution

The hydrogen bonding of hexahalometallate anions with various organic cations is explored via crystallographic and solution NMR studies.

Structural Variety in Solvated Lanthanoid(III ) Halide Complexes

Treatment of lanthanum metal with CH2Br2 or CH2I2 in tetrahydrofuran (thf) under ultrasound conditions yields the corresponding [LaX3(thf)4] (X = Br, I) complexes in good yield. Recrystallization of [LaBr3(thf)4] from 1,2-dimethoxyethane (dme) or bis(2-methoxyethyl) ether (diglyme) generates [LaBr2(µ-Br)(dme)2]2 and [LaBr2(dig-lyme)2][LaBr4(diglyme)]. Treatment of lanthanoid metals with hexachloroethane in dme yields [LnCl3(dme)2] (Ln = La, Nd, Er or Yb) and in acetonitrile [YbCl2(MeCN)5]2[YbCl3(MeCN)(-Cl)2YbCl3(MeCN)]. The reaction of Yb metal pieces with 1,2-dibromoethane in thf and dme gave single crystals of [YbBr3(thf)3] and [YbBr3(dme)2], respectively. The X-ray determined structure of [LaBr3(thf)4] shows a seven-coordinate monomer with pentagonal-bipyramidal stereochemistry and apical bromide ligands. For [YbBr3(thf)3], a monomeric structure with mer-octa-hedral stereochemistry is observed. In [LaBr2(µ-Br)(dme)2]2, two eight-coordinate La centres are linked by two bridging bromides. The dme ligands have a trans relationship to each other, and cis terminal bromides are transoid to the bridging bromides with dodecahedral stereochemistry for La. By contrast, the 1: 1.5 diglyme adduct is found to be ionic [LaBr2(diglyme)2][LaBr4(diglyme)], with an eight-coordinate bicapped trigonal-prismatic lanthanum cation and a seven-coordinate pentagonal-bipyramidal lanthanum anion. In the cation, the bromide ligands are cis to each other, and in the anion, two bromides are equatorial and two are axial. In [YbBr3(dme)2], [YbCl3(dme)2] and [ErCl3(dme)2], a seven-coordinate pentagonal-bipyramidal arrangement exists with apical halogen ligands. Far-infrared data, and in particular the absence of absorptions attributable to Ì(La–Clter), suggest that [LaCl3(dme)] is polymeric with six bridging chlorides per lanthanum. For [YbCl2(MeCN)5]2[YbCl3(MeCN)(-Cl)2YbCl3-(MeCN)], a remarkable ionic structure, with pentagonal-bipyramidal [YbCl2(MeCN)5]+ cations and octahedral di-nuclear [YbCl3(MeCN)(-Cl)2YbCl3(MeCN)]2– counter ions, is observed. In the former, chloride ligands are apical, while the MeCN ligands of the latter are transoid.