Synthesis and measurement of structural and magnetic properties of K-doped LaCoO_3 perovskite materials

Polycrystalline La1-xKxCoO3 （0≤ x ≤ 0.2） rare earth cobaltates have been synthesized by a solution combustion method using glycine as a fuel. The synthesized ceramic materials were characterized by powder X-ray diffraction （XRD）, scanning electron microscopy （SEM）, Fourier transform infrared spectroscopy （FTIR）, and magnetic measurements and studied for physical properties, such as photoeatalytic activity. FTIR measurements in conjunction with XRD showed that phases beyond 10% K doping are accompanied by small amounts of impurities. Chemical titrations show the presence of Co^4＋ and account for the Co^3＋-Co^4＋ mixed-valency of the system. The parent LaCoO3 shows spin-glass transition at low temperatures, whereas doped samples show transition from spin-glass behavior to paramagnetic ordering on progressive doping of K. ＂Mixed-conductor＂ nature of these ceramics positions them as viable candidates for solid oxide fuel cell （SOFC） applications.

Hydrothermal Synthesis,Crystal Structure and Magnetic Properties of a Cobalt(II) Coordination Polymer Assembled by 4-Sulfophthalate and 4,4'-Bipyridine

A novel metal-organic coordination polymer {[Co2（4-sphth）2（4,4＇-bpyh（H2O）4]- [Co（4,4＇-bpy）2（H2O）4]}, （4-sphth = 4-sulfophthalic acid, 4,4＇-bpy = 4,4＇-bipyridine） 1 has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analyses, IR spectroscopy, and magnetic susceptibility measurements. The complex crystallizes in monoclinic, space group C2/c with a = 18.893（6）, b = 23.080（7）, c = 22.473（7） A, fl = 107.311 （4）°, V = 9356（5） A^3, C76H70Co3N12O22S2, Mr = 1744.35, De = 1.238 g/cm^3,μ（MoKα） = 0.640 mm^-1, F（000） = 3596, Z = 4, the final R = 0.0444 and wR = 0.0846 for 9178 observed reflections （I 〉 2σ（I））. It exhibits a novel three-dimensional supramolecular network formed by hydrogen-bonding and π-π interactions. Variable-temperature magnetic measure shows an overall anti-ferromagnetic behavior for compound 1.

Hydrothermal Synthesis, Crystal Structure and Magnetic Properties of a Novel Zero-dimensional Manganese(Ⅱ) Complex with 2,2′-Diphenic Acid and 1,10-Phenanthroline Ligands

A novel metal-organic coordination polymer [Mn3（2,2′-dipha）3（phen）6]n·3nH2O （2,2′-dipha = 2,2′-diphenic acid, phen = 1,10-phenanthroline） 1 has been hydrothermally synthesized and structurally characterized by single-crystal X-ray diffraction, elemental analyses, IR spectroscopy, and magnetic susceptibility measurements. The crystal crystallizes in triclinic, space group P1 with a = 16.921（5）, b = 18.307（5）, c = 18.450（5）A , α = 113.369（5）, β = 108.529（5）, γ = 102.984（5）°, V = 4553（2）A^ 3, C114H72Mn3N12O14.25, Mr = 2002.66, Dc = 1.461 g/cm^3, μ（MoKα） = 0.488 mm^-1, the final F（000） = 2058, Z = 2, R = 0.0491 and wR = 0.0980 for 9087 observed reflections （I 〉 2σ（I））. In the crystal structure, the manganese atom is six-coordinated with two carboxylate oxygen atoms from different carboxylate groups of the same dipha and four nitrogen atoms from two different phen ligands, showing a slightly distorted octahedral geometry. Fur- thermore, it exhibits a zero-dimensional structure with dipha-Mn-phen- as building units. Variable- temperature magnetic measure shows an overall anti-ferromagnetic behavior for compound 1.

Hydrothermal synthesis and magnetic property of NaV_2O_5 nanorods

One dimensional rod like NaV 2O 5 was synthesized by hydrothermal method, which draws much attention as an exotic spin Peierls compound. The samples have been characterized by X ray diffraction (XRD), transmission election microscopy (TEM), and magnetic susceptibility measurements. The pH value and the reducing agent are critical for synthesizing NaV 2O 5 nanorods. The reducing agent NH 2OH may play a key role in the assembly and growth of nanorods of products. [

Synthesis and biochemical properties of fluorescent/magnetic bifunctional starch particles

Magnetic starch particles(MSPs) were synthesized in water-in-oil microemulsion at room temperature.MSPs were characterized by transmission electron microscopy(TEM),Fourier transform infrared spectrometry(FTIR),zeta potential system,thermogravimetric analysis(TGA) and vibrating sample magnetometry(VSM).The average diameter of the MSPs was 220 nm,dispersed with well-proportioned size and magnetic resonance,the saturation magnetization was 3.64 A·m2/kg.MSP was coated with poly-L-lysine(PLL),and then the surface of PLL-MSP was combined with fluorescein isothiocynate(FITC).Results show that fluorescent/magnetic starch particles(FMSPs) are of stable photo-bleaching capability compared with free FITC,with low bio-toxicity and certain function of magnetic separation.It is expected that FMSPs are bifunctional nano-materials including fluorescence labelling and magnetic separation.

Chemical Synthesis and Magnetic Properties of Nanocrystalline (La_(0.67-X)Gd_X)Sr_(0.33)MnO_3 Using Amorphous Molecular Alloy as Precursors

A new route to synthesize nanosized crystalline of （La0.67-xGdx）Sr0.33MnO3 （X=0.05, 0.10, 0.15, 0.20） perovskite-type complex oxides at calcination temperature of 600-1000℃ using the amorphous molecular alloy as precursors was reported. The precursor could be completely decomposed into complex oxide at temperature below 500℃ according to the TGA and DTA results. XRD demonstrates that the decomposed species is composed of perovskite-type structure at calcination temperature of 600℃ for 2 h. The particle size that depends on the calcination temperature of the precursor is in a range of 30-120 nm as determined by transmission electron microscopy （TEM）. This method is effective and can be easily quantitatively controlled to synthesize nanosized perovskite-type complex oxides. The magnetic properties of （La0.67 xGdx）Sr0.33MnO3 nanocrystalline were preliminary studied.

Direct hydrothermal synthesis and magnetic property of titanate nanotubes doped magnetic metal ions

Pure titanate nanotubes and titanate nanotubes doped with Fe^3＋/Ni^2＋/Mn^2＋ ions were synthesized by the hydrothermal method. In this process,titanate nanotubes were first prepared synchronously with doping Fe^3＋/Ni^2＋/Mn^2＋ 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 Fe^3＋/Ni^2＋/Mn^2＋ ions are paramagnetic behaviors.

Hydrothermal Synthesis, Crystal Structure and Properties of a New Copper Coordination Polymer [Cu2I（C7H5N4）2]n with 3-（Pyridin-2-yl）-1,2,4-triazole) Ligand

A new copper coordination polymer[Cu2I(C7H5N4)2]n(1)with the 3-(pyridin-2-yl)-1,2,4-triazole(Hpt)and copper iodide was synthesized.It crystallizes in the triclinic space group P1 with a=8.6380(9),b=9.2434(9),c=11.8588(12)A,α=99.5890(10)o,β=109.0990(10)o,γ=105.2800(10)o,V=829.25(15)A^3,Dc=2.180 g/cm3,Z=2,F(000)=522,GOOF=1.046,the final R=0.0245 and wR=0.0598.The crystal structure shows that two copper ions are bridged by twoμ2-η1:η0-3-(pyridin-2-yl)-1,2,4-triazole anions and two iodide ions.The coordination environments of the Cu ion are Cu(1)N5 and Cu(2)N2I2,giving distorted square pyramidal geometry and trigon pyramid geometry.The magnetic and fluorescent properties of 1 were studied.

Syntheses,Crystal Structures,and Magnetic Properties of Cobalt(Ⅱ) Complexes with 1,1-Cyclohexanediacetic Acid

Two new Co（Ⅱ） coordination polymers,{[Co_3（Hchda）_2（chda）_2（bpp）_2（H_2O）_2]}_n 1 and {[Co（chda）（bpe）（H_2O）]·3H_2O}_n 2（H_2chda = 1,1-cyclohexanediacetic acid,bpp = 1,3-bis（4-pyridinyl）propane and bpe = 1,2-bis（4-pyridinyl）ethylene）,were hydrothermally synthesized and then characterized by elemental analysis,IR spectroscopy,thermogravimetric analysis（TGA）,and single-crystal X-ray diffraction.Complex 1 possesses an infinite metal-organic layer based on triply bridged linear trinuclear subunits and complex 2 exhibits a square（4,4） grid layer with dangling lateral arms resulting from eight-membered rings above and below the layer.In addition,magnetic properties of complexes 1 and 2 are also given.

Magnetic properties of nanostructural γ-Ni-28Fe alloy

Nanostructural γ-Ni-28Fe alloy(nano γ-Ni-28Fe)was successfully prepared by mechanochemical alloying(MCA).The relationship between the microstructure and the synthesis conditions was investigated by using XRD,TEM,SEM as well as BET analyzer.The results show that nano γ-Ni-28Fe alloy is composed of a gamma phase(FCC structure).Its grain size is about 20 nm at reduction temperature below 600 ℃.The magnetic measurements indicate that the saturation magnetization of nano γ-Ni-28Fe alloy is 102.4 A·m2/kg,and the coercivity is much higher than that of conventional coarse-grained counterpart.The result may be attributed to its decrease of the grain size and chemical composition in nano γ-Ni-28Fe alloy.

Mixed-ligands Self-assembly Strategy Affording a New 4-Fold Interpenetrated 3D Co(Ⅱ)-based Coordination Polymer: Synthesis, Crystal Structure and Magnetic Property

A new Co(Ⅱ)-based coordination polymer, namely [Co(L)0.5(4,4?-bipy)0.5(H2 O)2]n(1,H4 L = 1,3-di(3?,5?-dicarboxylphenyl)benzene, 4,4′-bipy = 4,4′-bipyridine), has been hydrothermally synthesized using the mixed-ligands self-assembly strategy and further fully characterized. The crystal structure is of monoclinic, space group C2/c with a = 18.9124(10), b = 11.6150(5), c =15.4380(6)A,β= 110.989(5)°, V = 3166.2(2)A^3, C16 H13 CoNO6, Mr = 374.20, Z = 8, Dc = 1.570 g·cm^–3, F(000)= 1496,μ= 1.116 mm^–1, R = 0.0461 and wR = 0.1312 for 2328 observed reflections(I > 2s(I)). The crystal structure analysis revealed that 1 is a 4-fold interpenetrated three-dimensional(3D) framework with(3,4)-connected dmd-type topology. Moreover, the thermal stability and magnetic property of 1 were also investigated.

Tailoring the optical and magnetic properties of La-BaM hexaferrites by Ni substitution

We investigate the impact of Ni insertion on the structural,optical,and magnetic properties of Ba_(0.8)La_(0.2)Fe_(12-x)Ni_(x)O_(19)hexaferrites(Ni substituted La-BaM hexaferrites).Samples were prepared using the conventional co-precipitation method and sintered at 1000℃for 4 hours to assist the crystallization process.An analysis of the structure of the samples was carried out using an x-ray diffraction(XRD)spectrometer.The M-type hexagonal structure of all the samples was confirmed using XRD spectra.The lattice parameters a and c were found to be in the ranges of 5.8925±0.001 nm–5.8952±0.001 nm and 23.2123±0.001 nm–23.2219±0.001 nm,respectively.The M-type hexagonal nature of the prepared samples was also indicated by the presence of corresponding FT-IR bands and Raman modes in the FT-IR and Raman spectra,respectively.EDX results confirmed the successful synthesis of the samples according to the required stoichiometric ratio.A UV-vis spectrometer was used to record the absorption spectra of the prepared samples in the wavelength range of 200 nm–1100 nm.The optical energy bandgap of the samples was found to be in the range of 1.21 eV–3.39 eV.The M–H loops of the samples were measured at room temperature at an applied magnetic field range of 0 kOe–60 kOe.A high saturation magnetization of 99.92 emu/g was recorded in the sample with x=0 at a microwave operating frequency of 22.2 GHz.This high value of saturation magnetization is due to the substitution of La3+ions at the spin-up(12k,2a,and 2b)sites.The Ni substitution is proven to be a potential candidate for the tuning of the optical and magnetic parameters of M-type hexaferrites.Therefore,we suggest that the prepared samples are suitable for use in magneto-optic applications.

Morphology, Size-controlled Synthesis of CoO Nanostructure and Its Magnetic Property

CoO nanostructures with tunable morphology and size have been prepared via a simple one-pot solvothermal synthesis. The as-prepared nanoparticles were fully characterized using X-ray diffraction（XRD）, transmission electron microscopy（TEM）, field-emission scanning electron microscope（FESEM）, etc. The morphology and size of the product can be easily controlled by adjusting the raw materials added. Reaction time and the solvent ratio also play important roles in the synthesis of octahedral nanostructures. The magnetic property of the as-prepared samples was also investigated.

AgCu(IO3)3：Synthesis,Crystal Structure and Magnetic Property

A new mixed metal iodate, namely Ag Cu（IO3）3, has been prepared using hydrothermal method. Ag Cu（IO3）3 crystallizes in the triclinic group P1 with a = 7.3063（6）, b = 7.8050（6）, c = 8.2447（6） A, α = 67.212（7）, β = 74.978（7）, γ = 80.972（7）°, V = 417.80（6） A^3 and Z = 2. The structure features one-dimensional [Cu（IO3）3]n^n- anionic chains that are separated by Ag~＋ cations. Such [Cu（IO3）3]n^n- chain is composed of [Cu2O（11）]n chain decorated by unidentate hanging and bidentate bridging iodate groups. Thermal study implies that Ag Cu（IO3）3 is thermally stable up to 460 oC and the optical measurement determined the optical band gap of 3.11 eV with a broad absorption band centered at 765 nm. Magnetic investigations show that Ag Cu（IO3）3 is a soft ferromagnet.

Solution combustion synthesis of Fe-Ni-Y_2O_3 nanocomposites for magnetic application

Fe-Ni-Y2O3 nanocomposites with uniform distribution of fine oxide particles in the gamma Fe Ni matrix were successfully fabricated via solution combustion followed by hydrogen reduction. The morphological characteristics and phase transformation of the combusted powder and the Fe-Ni-Y2O3 nanocomposites were characterized by XRD, FESEM and TEM.Porous Fe-Ni-Y2O3 nanocomposites with crystallite size below 100 nm were obtained after reduction. The morphology, phases and magnetic property of Fe-Ni-Y2O3 nanocomposites reduced at different temperatures were investigated. The Fe-Ni-Y2O3 nanocomposite reduced at 900 °C has the maximum saturation magnetization and the minimum coercivity values of 167.41 A/(m2·kg)and 3.11 k A/m, respectively.

Preparation and magnetic properties of nanosized (La_(0.47)Gd_(0.2))Sr_(0.33)MnO_3

Nanosized (La0.47 Gd0.2)Sr0.33MnO3 perovskite oxides were prepared at relatively low calcinating temperature of 600℃ and 800℃ for 10h using amorphous complex precursor. Curie temperatureTc and magnetocaloric effects（MCE） were investigated. X-ray diffraction（XRD） and electron diffraction（ED） reveal that the resulting products are of pure single-phase rhombohedral perovskite structure. Transmission electron microscopy（TEM） observation finds that the particle sizes are about 40-50nm and 80-100nm, and the Tc are 285.1K and 285.9K, MCE are about 2.02J/（kg·K-1 ） and 3.90J/（kg·K-1 ） at 5T magnetic field. A relatively large MCE with a broad peak around Curie temperature is observed in sample sintered at 800℃ for 10h. This suggests that nanosized (La0.47 Gd0.2)Sr0.33MnO3 is a suitable material as working substance in magnetic refrigeration in room temperature.

Hydrothermal Synthesis and Characterization of PEG-Mn_3O_4 Nanocomposite

Here, we report on the synthesis of PEG-Mn_3O_4 nanocomposite(NP's) via a hydrothermal route by using Mn(acac)2, ethanol, NH3 and PEG-400. The crystalline phase was identified as Mn_3O_4. The crystallite size of the PEG-Mn_3O_4 nanocomposite was calculated as 12±5 nm from X-ray line profile fitting and the average particle size from TEM was obtained as 200 nm. This reveals polycrystalline character of Mn_3O_4 NP's. The interaction between PEG-400 and the Mn_3O_4 NP's was investigated by FTIR. Temperature independent AC conductivity of PEG-Mn_3O_4 nanocomposite beyond 20 k Hz provides a strong evidence of ionic conduction through the structure. The conductivity and permittivity measurements strongly depend on the secondary thermal transition of nanocomposite beyond 100. Above that temperature, Mn_3O_4 particles may interact with each other yielding a percolated path that will facilitate the conduction. On the other hand, the relatively lower activation energy(Ea=0.172 e V) for relaxation process suggests that polymer segmental motions of PEG and electrons hopping between Mn2+and Mn3+may be coupled in the sample below 100. Room temperature magnetization curve of the sample does not reach to a saturation, which indicates the superparamagnetic character of the particles. As the temperature increases, the frequency at which(ε′′) reaches a maximum shifted towards higher frequencies. The maximum peak was observed at 1.4 k Hz for 20 while the maximum was detected at 23.2 k Hz for 90.

Large-scale synthesis of nickel sulfide micro/nanorods via a hydrothermal process

Rhombohedral-phase NiS micro/nanorods were synthesized on a large scale through a hydrothermal method using NiCl2·6H2O and thiourea crystals as starting precursors. Recrystallized thiourea was observed to play an important role in the formation of mi- cro/nanosized rods and flower-like structures. The molar ratio and reaction temperature of the precursors influenced the morphology and phase of NiS products. Pure rhombohedral NiS micro/nanorods were obtained on a large scale when the molar ratio between NiCl2·6H2O and thiourea crystals was fixed at 2：1, and the mixture was heated at 250℃ for 5 h. Flower-like NiS nanostructures were formed when the molar ratio between NiCl2·6H2O and thiourea crystals was maintained at 1：1. The Raman and Fourier-transform infrared （FTIR） spectra of the as-prepared rhombohedral NiS micro/nanorods were collected, and their magnetic properties were investigated. The results showed that the FTIR absorption peaks of the as-prepared product are located at 634 cm^-1 and their Raman peaks are located at 216 and 289 cm^-1; the as-prepared NiS micro/nanorods exhibited weak ferromagnetic behavior due to the size effect.

Hydrothermal synthesis, crystal structure and magnetic properties of a Dy~Ⅲ-Fe~Ⅲ heteronuclear complex

A new 3d-4f heteronuclear complex [Fe（phen）3]2[FeDy（H2O）（tiron）3]·6H2O （1,Na2H2tiron=disodium 4,5-dihydro-xybenzene-1,3disulfonate） was synthesized by the hydrothermal reaction. The complex crystallized in the cubic system, space group P213 with the cell parameters：a=2.18786（14）nm, V=10.4727（12）nm3 , Z=4, F（000）=4720, R1=0.0493, wR2 =0.1165, S=1.05. In each [FeDy（H2O）（tiron）3]6-unit, it was revealed that the Fe3＋ ion was in a FeO6 distorted trigonal anti-prism coordination polyhedron completed by six phenolate O atoms from three tiron 4- ligands, while Dy3＋ in a DyO7 distorted monocapped trigonal anti-prism coordination polyhedron completed by three phenolate μ2-O atoms and three O atoms from sulfonate groups of three ligands and one O atom from water. The magnetic properties of the complex was determined in the range of 2-300K, indicating the antiferromagnetic interaction between the central DyIII-FeIII ions.

Hydrothermal Synthesis and Magnetic Properties of SmCr0.5M0.5O3（M=Fe and Mn） Micro-plates

Nanostructured B-site Fe and Mn doped SmCrO3 was prepared by mild hydrothermal growth. The as-prepared crystals are mainly micrometer-scale plates, ranging from rhombus（SmCr0.5Fe0.5O3） to elongated hexagonal（SmCr0.5Mn0.5O3）, and finally to well-edged rectangular（SmCr0.17Mn0.5Fe0.33O3） plates. Fe and Mn doped SmCrO3 crystals are indexed into Pbnm space group. The cell parameters of SmCr0.5Fe0.5O3 are slightly smaller than that of pristine SmCrO3. Binding energy analysis of Cr, Mn and Fe in SmCr0.17TMn0.5Fe0.33O3 sample indicates that they all possess ＋3 oxidation states. Temperature dependent magnetization of the as-prepared samples presents obviously stronger ferromagnetic interactions than the undoped counterparts. This work represents a remarkable development for hydrothelmal synthesis into fabricating perovskite oxide crystals with uniform distribution of doping ions.