magnetic properties

摘要： Using two new flexible and functional nitronyl nitroxide radicals as ligands, two copper (II) complexes {[Cu(hfac)2]3(NITmPhO3Py)2}n (1) and [Cu(hfac)2 (NIToPhO3Py)]2 (2) (NITmPhO3Py = 2-[(3-methoxy-pyridinyl)phen-3-yl]- 4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, NIToPhO3Py = 2-[(3-methoxy-pyridinyl)phen-2-ly]-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, hfac = hexafluoroacetylacetone), have been characterized structurally and magnetically. The X-ray crystal analyses showed that complex 1 displayed a chain polymer structure which formed with {[Cu(hfac)2]3(NITmPhO3Py)2}n due to the cross-linking of two cyclic binuclear fragments {[Cu(hfac)2]2(NITmPhO3- Py)2} via the bridging unit [Cu(hfac)2];complex 2 presented a binuclear cyclic structure [Cu(hfac)2]2(NIToPhO3Py)2. The magnetic behaviors of the two complexes 1 and 2 have been investigated. Magnetic studies showed that antiferromagnetic interactions dominated in complex 1, while there existed ferromagnetic interactions between Cu(II) and coordinated NO group in complex 2.

摘要： Ferrite ceramics,Ni_(0.88)Zn_(0.07)Co_(0.05)Fe_(1.98)O_(4),with the addition of 4 wt.%Bi_(2)O_(3) as sintering aid,were fabricated by using a simple one-step processing without involving the step of calcination.X-ray diffraction(XRD)results indicated that single phase ferrite ceramics can be achieved after sintering at 1000°C for 2 h.The samples demonstrated relative densities in the range of 97-99%.Desired magneto-dielectric properties have been approached by adjusting the sintering temperature and sintering time duration.This technique is believed to be applicable to other ceramic materials.

摘要： Nano-crystalline CrxCoFe2–xO4 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) ferrites were synthesized by sol-gel method. The X-ray diffraction patterns of all the samples provide information about the existence of single phase spinel structure. The SEM and TEM micrographs show the uniform particle distribution and SAED pattern represents the polycrystalline nature of the resultant ferrite nano-particles. High purity of the sample is confirmed by energy dispersive X-ray analysis. The FTIR spectra show two strong absorption bands in the range of 600 - 400 cm–1, which confirm the presence of M-O stretching band in ferrites. The magnetic properties of the synthesized samples were investigated by using vibrating sample magnetometer at room temperature. According to VSM reports the main magnetic parameters like saturation magnetization (Ms), coercivity (Hc) were found to decrease with the substitution of Cr3+ content. Possible mechanisms which are responsible for the results are scrutinized minutely in this paper.

摘要： The fact that there are Mn^(2+) at the A sites in the ABO_3 perovskite phase of manganites with the nominal composition La_(0.6-x)Nd_xSr_(0.1)MnO_3 showed by detailed experimental study and theoretical calculations.The magnetic moments of these Mn^(2+) are antiparallel to those of the Mn ions at the B sites.The content of the Mn^(2+) increases as the average ionic radius,,of the ions at A sites decreases,resulting in the experimentally observed phenomenon that the content of the Mn_3O_4 phase in the manganites decreases with decreasing .

摘要： The thickness of CoP thin films prepared by wet chemical deposition is of crucial importance on magnetic property and recording perform-ance. The coercivity of CoP films decreased with increasing film thickness. The coercivity was 45.37 kA m 1 at the thickness of 300 nm, and decreased to 21.65 kA m 1 at 5.7 μm. Recording performance tests indicate that, for drums with the same size, different recorded magnetic pole density have different thickness requirements. For 40 mm diameter magnetic drum, the optimal CoP thickness is 3～10 μm for 256 re-corded magnetic poles, 1～2 μm for 512 recorded magnetic poles, and 500～800 nm for 1024 recorded magnetic poles.

摘要： Pure titanate nanotubes and titanate nanotubes doped with Fe3+/Ni2+/Mn2+ ions were synthesized by the hydrothermal method. In this process, titanate nanotubes were first prepared synchronously with doping Fe3+/Ni2+/Mn2+ ions. The morphology,structure, thermal stability and magnetic property of titanate nanotubes were characterized by X-ray diffraction (XRD), transmission electron microscope (TEM), and magnetic measurement. The titanate nanotubes transformed into the anatase titania nanocrystals,and further the mixture of anatase and rutile titania along with increasing temperature. The results indicate that the titanate nanotubes doped with Fe3+/Ni2+/Mn2+ ions are paramagnetic behaviors.

摘要： The self-assembly reactions of MⅡCl2 (M = Ni, Co) with the flexible bix ligand [bix = 1,4-bis(imidazole-1-ylmethyl)benzene] yielded a 2D network [NⅢ(bix)2Cl2]n 1 and a 1D chain [CoⅡ(bix)Cl2]n 2. Their crystal structures have been determined by X-ray single-crystal diffraction analysis. Complex 1 characters a two-dimensional grid-type structure and crystallizes in monoclinic, space group P21/c with a = 7.7231(7), b = 12.7787(9), c = 13.9374(13)(A), β = 105.419(4)°, C28H28Cl2N8Ni, Mr = 606.19, Ζ = 2, V = 1326.0(2)(A)3, Dc = 1.518 g/cm3, μ = 0.969 mm-1, F(000) = 628, R = 0.0429 and wR = 0.0783 for 2503 observed reflections (Ⅰ＞ 2σ(Ⅰ)). Compound 2 is a one-dimensional chain and crystallizes in orthorhombic, space group Pbca with a = 11.3696(6), b = 10.2128(6), c = 14.4943(9) (A), C14H14Cl2CoN4, Mr = 368.12, Z = 4, V = 1683.01(17)(A)3, Dc = 1.453 g/cm3, μ = 1.334 mm-1, F(000) = 748, R = 0.0317 and wR = 0.0800 for 1778 observed reflections (Ⅰ＞ 2σ(Ⅰ)). Magnetic properties of the title complexes were also investigated.

摘要： A new two-dimensional polymeric manganese compound [Mn(PhCOO)2(4,4'-bipyridine)]n 1 has been prepared and structurally characterized by X-ray diffraction. The complex crystallizes in space group Pbcn with a = 18.7158(2), b = 11.6919(3), c = 9.4799(2)(A), V = 2074.42(7)(A)3, Z = 4, Mr = 453.34, Dc = 1.452 g/cm3, μ = 0.670 mm-1 and F(000) = 932. The final refinement gave R = 0.0458 and wR = 0.1439 for 1358 observed reflections with Ⅰ＞ 2σ(Ⅰ). The complex consists of repeating units of Mn(PhCOO)2(4,4'-bipyridine). Each Mn center is sixcoordinated by four carboxylate O atoms of four benzoate anions and two pyridyl N atoms from bipy ligands to furnish a slightly distorted octahedral geometry. The two adjacent Mn atoms are connected by a pair of μ1,3-carboxylate groups to form infinite chains, which are further interlinked by bipy to complete a 2D grid network. The magnetic property of the polymeric complex has also been investigated.

摘要： Boron carbide nanotubes (nano-fibers) was prepared by B powder and carbon nanotubes (CNTs) at high temperature in a vacuumed quartz tube.The morphology,microstructure,component and magnetic property of samples were characterized by transmission electron microscopy (TEM),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS)and magnetic property measurement system (MPMS) controller.The results showed that B-doping CNTs have great difference in the morphology and magnetic property from those of pristine CNTs.