Molar Magnetic Susceptibility Research Articles

Oxygen Involvement in the Charge Compensation of LiMO2 Compounds and the Consequences for Battery Safety and Unprecedented Electrical Magnetic Properties

An intimate view of the operando electronic and atomic structure local to oxygen and transition metals in LiMO2 cathodes has been developed. We present here a combination of in-situ and operando measurements of structure, resistivity and magnetic susceptibility to expose the direct role of oxygen in charge compensation reactions. The formation of electron holes at oxygen sites, as detected by X-ray absorption spectroscopy (XAS), is a prerequisite for oxygen evolution reactions that can lead to battery fires. However, the same reaction, if managed well can lead to beneficial switching behavior of their magnetic and electrical properties. The magnetic susceptibility of LixCoO2 has been studied in composition range of 0.94 ≤ x ≤ 0.75. A consistent and linear increase in susceptibility with respect to decreasing lithium content has been observed with the notable exception of a sharp decrease in susceptibility at x = 0.94. This sharp change in molar magnetic susceptibility as well as the associated change in resistivity has potential use in neuromorphic memory applications.

Mixed-ligand metal complexes containing an ONS Schiff base and imidazole/benzimidazole ligands: synthesis, characterization, crystallography and biological activity

Salicylaldehyde-4-methylthiosemicarbazone (H2MTSali) has been prepared via the condensation reaction of 4-methyl-3-thiosemicarbazide and salicylaldehyde. Four new mixed-ligand copper(II) and nickel(II) complexes with a general formula [M(MTSali)L] (M = Cu2+ or Ni2+; L = co-ligand) were synthesized, where L is either imidazole (im) or benzimidazole (bzim). The Schiff base and its mixed-ligand complexes were characterized by IR and UV/Vis spectroscopy, and the complexes by molar conductivity and magnetic susceptibility measurements. The spectroscopic data indicated that the Schiff base behaves as a tridentate ONS donor ligand coordinating via the phenoxide-oxygen, azomethine-nitrogen, and thiolate-sulphur atoms. Magnetic data indicate a square planar environment for the nickel(II) complexes while molar conductance values indicate that the metal complexes are essentially non-electrolytes in DMSO solution. X-ray crystallography shows Cu(MTSali)bzim (1) and Ni(MTSali)bzim (3) to be isostructural, with the metal(II) ions being coordinated by a N2OS donor set that defines an approximate square planar geometry; in both cases, the benzimidazole is splayed with respect to the coordination plane. The copper(II) complexes were active against MDA-MB-231 and MCF-7 breast cancer cell lines, more so than H2MTSali, whereas the nickel(II) complexes were inactive.

Synthesis, characterization, biological and catalytic applications of transition metal complexes derived from Schiff base

A novel series of Cu(II), Ni(II), Zn(II), Co(II), and Cd(II) complexes have been synthesized from the Schiff base. Structural features were determined by analytical and spectral techniques like IR, 1H NMR, UV–vis, elemental analysis, molar electric conductibility, magnetic susceptibility and thermal studies. The complexes are found to be soluble in dimethylformamide and dimethylsulfoxide. Molar conductance values in dimethylformamide indicate the non-electrolytic nature of the complexes. Binding of synthesized complexes with calf thymus DNA (CT DNA) was studied. There is significant binding of DNA in lanes 2, 3, and 5. Lanes 4 and 6 are showing more florescence when compared to the control indicating that these molecules are strongly bound to the DNA by inserting themselves between the two stacked base pairs and exhibiting their original property of fluorescence. Angiogenesis study has revealed that the compounds B-2, B-4 and B-5 have potent antitumor efficacy and activation of antiangiogenesis could be one of the possible underlying mechanisms of tumor inhibition.

Redox-active porous coordination polymers prepared by trinuclear heterometallic pivalate linking with the redox-active nickel(II) complex: synthesis, structure, magnetic and redox properties, and electrocatalytic activity in organic compound dehalogenation in heterogeneous medium.

Linking of the trinuclear pivalate fragment Fe2CoO(Piv)6 by the redox-active bridge Ni(L)2 (compound 1; LH is Schiff base from hydrazide of 4-pyridinecarboxylic acid and 2-pyridinecarbaldehyde, Piv(-) = pivalate) led to formation of a new porous coordination polymer (PCP) {Fe2CoO(Piv)6}{Ni(L)2}1.5 (2). X-ray structures of 1 and 2 were determined. A crystal lattice of compound 2 is built from stacked 2D layers; the Ni(L)2 units can be considered as bridges, which bind two Fe2CoO(Piv)6 units. In desolvated form, 2 possesses a porous crystal lattice (SBET = 50 m(2) g(-1), VDR = 0.017 cm(3) g(-1) estimated from N2 sorption at 78 K). At 298 K, 2 absorbed a significant quantity of methanol (up to 0.3 cm(3) g(-1)) and chloroform. Temperature dependence of molar magnetic susceptibility of 2 could be fitted as superposition of χMT of Fe2CoO(Piv)6 and Ni(L)2 units, possible interactions between them were taken into account using molecular field model. In turn, magnetic properties of the Fe2CoO(Piv)6 unit were fitted using two models, one of which directly took into account a spin-orbit coupling of Co(II), and in the second model the spin-orbit coupling of Co(II) was approximated as zero-field splitting. Electrochemical and electrocatalytic properties of 2 were studied by cyclic voltammetry in suspension and compared with electrochemical and electrocatalytic properties of a soluble analogue 1. A catalytic effect was determined by analysis of the catalytic current dependency on concentrations of the substrate. Compound 1 possessed electrocatalytic activity in organic halide dehalogenation, and such activity was preserved for the Ni(L)2 units, incorporated into the framework of 2. In addition, a new property occurred in the case of 2: the catalytic activity of PCP depended on its sorption capacity with respect to the substrate. In contrast to homogeneous catalysts, usage of solid PCPs may allow selectivity due to porous structure and simplify separation of product.

Synthesis and Structural Characterization of a Dimeric Cobalt(I) Homoleptic Alkyl and an Iron(II) Alkyl Halide Complex

The homoleptic cobalt(I) alkyl [Co{C(SiMe2Ph)3}]2 (1) was prepared by reacting CoCl2 with [Li{C(SiMe2Ph)3}(THF)] in a 1:2 ratio. Attempts to synthesize the corresponding iron(I) species led to the iron(II) salt [Li(THF)4][Fe2(μ-Cl)3{C(SiMe2Ph)3}2] (2). Both 1 and 2 were characterized by X-ray crystallography, UV–vis spectroscopy, and magnetic measurements. The structure of 1 consists of dimeric units in which each cobalt(I) ion is σ-bonded to the central carbon of the alkyl group −C(SiMe2Ph)3 and π-bonded to one of the phenyl rings of the −C(SiMe2Ph)3 ligand attached to the other cobalt(I) ion in the dimer. The structure of 2 features three chlorides bridging two iron(II) ions. Each iron(II) ion is also σ-bonded to the central carbon of a terminal −C(SiMe2Ph)3 anionic ligand. The magnetic properties of 1 reveal the presence of two independent cobalt(I) ions with S = 1 and a significant zero-field splitting of D = 38.0(2) cm–1. The magnetic properties of 2 reveal extensive antiferromagnetic exchange coupling with J = −149(4) cm–1 and a large second-order Zeeman contribution to its molar magnetic susceptibility. Formation of the alkyl 1 and the halide complex 2 under similar conditions is probably due in part to the fact that Co(II) is more readily reduced than Fe(II).

Controlling the magnetic characters co-existing at the novel nanometric multiferroic PrAlxFe1−xO3; 0.0 ⩽ x ⩽ 0.6 via an exchange bias interaction to open a new era of applications

For the first time, the nanometric multiferroic perovskites PrAlxFe1−xO3; 0.0⩽x⩽0.6, were synthesized and extensively studied. XRD results and tolerance factor calculations revealed the distorted orthorhombic single-phase structure for all synthesized samples. HRTEM micrographs for PrFeO3 (x=0.0) indicated homogeneous orthorhombic nanoparticles with high local crystallinity and highly ordered lattice planes. Interplanar d-spacing calculated from HRTEM accorded well with the d-values estimated from XRD. Introducing the undersized Al3+ cations to the B-site on the expenses of Fe3+ cations affected the crystallites’ size negatively and resulted in weak lattice inflation due to the BO6 octahedral tilting. As a result, PrAl0.1Fe0.9O3 (x=0.1) showed polycrystalline nature with deteriorated lattice arrangements, lower ordering and fair homogeneity. Magnetic hysteresis and DC molar magnetic susceptibility verified that this novel and unique series of nanometric multiferroics carries the antiferromagnetic (AFM) character as a secondary magnetic component inside all of its compositions. The existence of superparamagnetism (SPM) and ferromagnetism (FM) among selected x-values were also verified. PrFeO3 showed the superparamagnetic character, after which SPM to FM phase transition was established at x=0.1 with soft magnetic features and improved Ms, Mr and Hc values. Interesting magnetic hardening appeared at x=0.2 up to x=0.4 with further improvement of the magnetic constants. FM to AFM phase transition was reached at x=0.6 with the coexistence of the former two phases with different extents at 0.1⩽x-values⩽0.6. Competition between ferromagnetic and antiferromagnetic sub-lattices lead to a ferrimagnetic-like state and induced a phenomenon of exchange bias interaction which resulted in hysteresis necking at x=0.2 and 0.5. Our results are signatures of a complex magnetic structure considered as a magnetic core–shell-like system or a magnetic multilayer-like system with an exchange interaction between the FM/AFM heterosystems at their interfaces. Recorded Ms and Mr values exceed those reported in literature for RFeO3 multiferroics with weak ferromagnetic moment. Each sample in this series showed its own magnetic behavior and can be applied to a specific tailored application. New era of applications are expected for this new multiferroic series of perovskites as exchange bias materials.

Molar conductance, magnetic susceptibility, mass spectra, and thermal decomposition studies on Cu(II) compounds with substituted terpyridines and clioquinol drug

Octahedral copper(II) complexes with substituted terpyridines and clioquinol drug have been synthesized and characterized by elemental analysis, molar conductance, magnetic susceptibility, thermal decomposition, infrared spectra, 1H-NMR spectra, and FAB mass spectroscopy. The antibacterial activities of the newly synthesized compounds were evaluated and correlated with their physicochemical properties. Results revealed that the tested compounds exhibited better inhibitory activities than the reference antibacterial quinolone drugs against Gram(+ve) and Gram(−ve) bacteria.

A novel sulfur–nitrogen π-heterocyclic radical anion, (6H-1,2,3-benzodithiazol-6-ylidene)malononitrilidyl, and its homo- and heterospin salts

(6H-1,2,3-Benzodithiazol-6-ylidene)malononitrile (4) was electrochemically and chemically reduced with tetrakis(dimethylamino)ethylene (TDAE) and CrTol2 into the title radical anion (5). The electrochemically generated 5 and its salts [TDAE]2+[5]2 (7) and [CrTol2]+ [5] (8) were characterized by solution EPR in combination with UV–Vis spectroscopy. Salts 7 and 8 were isolated and characterized by elemental analysis and solid-state EPR, and 8 by magnetic measurements in the temperature range 2–300K. The value of the effective magnetic moment of the salt 8 at 300K, μeff=1.64μB, indicates π-dimerization of 5 in the solid state. For the molar magnetic susceptibility χ of 8, the temperature dependences of χT and 1/χ in the range 2–300K can be approximated by the Curie–Weiss law with the Curie–Weiss constant C and temperature Tc equal to 0.33±0.01cm3Kmol−1 and −1.0±0.1K, respectively. In the mean-field approximation, the effective value of the exchange interaction of [CrTol2]+ with its neighboring cations can be estimated as zJ=−1.4сm−1. All the experimental results were supported by DFT calculations.

A New Index for the Estimation of the Aromatic Character - II

A new aromaticity index has been proposed based on the energy of π orbital {-[π1+Σ2n(π1-πn)]×103} where n is the number of occupied orbitals. Calculations have been performed on aromatic and heteroaromatic compounds using DFT method at B3LYP/6-311G+(d,p) level. This index has been tested on 6π electron compounds, on bicyclic and polycyclic aromatic compounds and compared with HOMA, the molar magnetic susceptibility (XM), and the aromatic stabilization energy (ASE). In all the cases, a good correlation has been found. Keywords: Aromaticity, DFT, quantification of the aromatic character.

Tetranuclear copper(II) complex with the heterocyclic azomethine ligand: Crystal structure and magnetic properties

A tetranuclear copper(II) complex based on azomethine, which is the condensation product of 1-phenyl-3-methyl-4-formylpyrazol-5-one with 1,3-diaminopropan-2-ol, is synthesized. The complex includes two different tetranuclear clusters: symmetrical and unsymmetrical. They have a pseudo-cubane structure and are in a ratio of 1 : 2. The quantum-chemical calculation shows that the “unsymmetrical” conformer does not correspond to the local minimum on the molecular potential energy surface. Its existence is thus determined by the crystalline packing effects. According to the results of measurements of the temperature dependence of the magnetic susceptibility, the ground spin state is a singlet caused by the overall antiferromagnetic interaction between the copper ions. Accepting the molar magnetic susceptibility of the complex to be equal to the sum of susceptibilities of the “symmetrical” and “unsymmetrical” clusters and assuming that the spin-Hamiltonian for both clusters includes three exchange parameters, the temperature dependence of the magnetic susceptibility of the complex is satisfactorily described with the following parameters of the model: J1A = −178, J2A = 80, J3A = 18, J1B = −26, J2B = −74, J3B = 46 cm−1, gA = gB = 2.05.

Synthesis, structural characterization and biological studies of copper complexes with 2-aminobenzothiazole derivatives

Novel copper complexes of 2-aminobenzothiazole derivatives were synthesized by the condensation of Knoevenagel condensate acetoacetanilide (obtained from substituted benzaldehydes and acetoacetanilide) and 2-aminobenzothiazole. They were thoroughly characterized by elemental analysis, IR, 1H NMR, UV–Vis., MS Spectra, molar conductance, magnetic moment and electrochemical studies. These spectral studies suggested that distorted square planar geometry for all the complexes. Molar conductance data and magnetic susceptibility measurements provide evidence for monomeric and neutral nature of the complexes. The electrochemical behaviour of the ligand and complexes in DMSO at 298K was studied. The present ligand systems stabilize the unusual oxidation states of copper ion during electrolysis. Antibacterial screening of the ligands and their complexes reveal that all the complexes show higher activities than the free ligands.

Synthesis and Characterization of Template Cr(III),Fe(III), Mn(II), Cd(II) and V(IV), Complexes Derived from 2,6- Diaminopyridine and 1,4-Dihydro-Quinoxalin-2,3-dione.

A new series of tetradentate N2O2 acyclic complexes of type (M(L)X2)Xn where M = Mn(II), Cd, Cr(III) and Fe(III); L is tetradentate acyclic Schiff base formed via condensation reaction, and X = Cl-, n=1 for M(III), have been prepared on the basis of condensation of 2,6-diaminopyridine and 1,4-dihydro-quinoxalin-2, 3-dione by template method. The complexes are formulated as: (M(L)Cl)Cl where M=Cr, Fe(III),(MLCl2),MII=Mn, Cd(II) and (VOL)SO4 on the basis of elemental analyses,molar conductance and other spectral data. The organic moiety formed up on template condensation behaves as tetradentate N2O2 system through the two azomethine nitrogen atoms of -C=N- and the participation of O atoms of -C=O in 2- position of pyrazine ring. However, the pyridine nitrogen atom does not take part in coordination as confirmed by FTIR,UV-Visible and H NMR spectroscopy data. The newly template metal complexes have characterized with the help of various spectral techniques H NMR,13C NMR, F.T.I.R, elemental analyses, electronic spectra, molar conductivity measurements and magnetic susceptibilities. The octahedral geometry has been proposed for Cr(III),Fe(III), Mn (II) and Cd(II) while vanadyl complex was square pyramid configuration respectively. Keywords: Template complex, Quinoxaline-3, 2-dione, Schiff bases.

Synthesis, structures, sorption and magnetic properties of coordination polymers based on 3d metal pivalates and polydentate pyridine-type ligands

The reactions of 3d metal pivalates with pyridine-containing ligands of different structures afforded the 1D coordination polymers [Co2(Piv)4(dpe)2]n, [Ni(Piv)2(dpe)(EtOH)2]n, [Cu2(Piv)4(dpe)]n, [Cu(Piv)2(dpe)]n, [Ni(Piv)2(4-ptz)(EtOH)2]n, and [Cu2(Piv)4(4-ptz)· ·mSolv]n (Solv is EtOH, m = 2; Solv is C6H6, m = 1; Piv− is pivalate, dpe is trans-1,2-bis(4-pyridyl)ethylene, 4-ptz is 2,4,6-tris(4-pyridyl)-1,3,5-triazine), as well as the 3D coordination polymer [{Cu2(Piv)4}3(3-ptz)2]n (3-ptz is 2,4,6-tris(3-pyridyl)-1,3,5-triazine). The sorption and magnetic properties of a series of the synthesized compounds and magnetic properties of the earlier characterized coordination polymer [Mn2(O2CC6H5)4(dpe)2·dpe]n were studied. It was shown that the desolvation of the complexes [Ni(Piv)2(4-ptz)(EtOH)2]n and [Cu2(Piv)4-(4-ptz)·2EtOH]n resulted in the formation of the crystal structures, in which the pores are accessible to nitrogen and hydrogen at 78 K (SBET are up to 92 m2 g−1). The temperature dependences of the molar magnetic susceptibility for [Co2(Piv)4(dpe)2]n, [Mn2(O2CC6H5)4-(dpe)2·dpe]n, [Ni(Piv)2(dpe)(EtOH)2]n, [Ni(Piv)2(4-ptz)(EtOH)2]n, and [Cu2(Piv)4-(4-ptz)·2EtOH]n are described in terms of models taking into account the zero-field splitting and exchange interactions or isotropic exchange Hamiltonians.

Spin Crossover Iron(II) Coordination Polymer Chains: Syntheses, Structures, and Magnetic Characterizations of [Fe(aqin)2(μ2-M(CN)4)] (M = Ni(II), Pt(II), aqin = Quinolin-8-amine)

New Fe(II) coordination polymeric neutral chains of formula [Fe(aqin)2(μ2-M(CN)4)] (M = Ni(II) (1) and Pt(II) (2)) (aqin = Quinolin-8-amine) have been synthesized and characterized by infrared spectroscopy, X-ray diffraction, and magnetic measurements. The crystal structure determinations of 1-2 reveal in both cases a one-dimensional structure in which the planar [M(CN)4](2-) (M = Ni(II) (1) and Pt(II) (2)) anion acts as a μ2-bridging ligand, and the two aqin molecules as chelating coligands. Examination of the intermolecular contacts in the two compounds reveals that the main contacts are ascribed to hydrogen bonding interactions involving the amine groups of the aqin chelating ligands and the nitrogen atoms of the two non bridging CN groups of the [M(CN)4](2-) (M = Ni(II) (1) and Pt(II) (2)) anion. The average values of the six Fe-N distances observed respectively at room temperature (293 K) and low temperature (120 K), that is, 2.142(3) and 2.035(2) Å for 1, and 2.178(3) and 1.990(2) Å for 2, and the thermal variation of the cell parameters (performed on 2) are indicative of the presence of an abrupt HS-LS spin crossover (SCO) transition in both compounds. The thermal dependence of the product of the molar magnetic susceptibility times the temperature (χmT), in cooling and warming modes, confirms the SCO behavior at about 145 and 133 K in 1 and 2, respectively, and reveals the presence of a small thermal hysteresis of about 2 K for each compound.

Magnetic properties of ferrites-cobaltites Bi1 − x La x Fe1 − x Co x O3 (1.0 ≥ x ≥ 0.7) with a perovskite structure

The molar magnetic susceptibility (χmol) of Bi1 − xLaxFe1 − xCoxO3 solid solutions (x = 1.0, 0.9, 0.8, or 0.7) with a crystal structure of rhombohedrally distorted perovskite (R\(\bar 3\)c) has been investigated in the temperature range of 5–300 K in a 0.86 T magnetic field. In the temperature range where χmol depends on temperature T according to the Curie-Weiss law, the resulting effective magnetic moments of Fe3+ and Co3+ ions (\(\mu _{eff,Fe^{3 + } ,Co^{3 + } ,} \mu _{eff,Fe^{3 + } } \) and \(\mu _{eff,Co^{3 + } } \)) have been determined for the solid solutions under study. Fe3+ ions in the solid solutions have been found to be in the mixed intermediate spin (IS) and high spin (HS) states (\(\mu _{eff,Fe^{3 + } } \) is 4.26μB and 4.68μB for the temperature range of 5–100 and 150–300 K, respectively). It is shown that 8% Co3+ ions in LaCoO3 at 5–19 K are in the paramagnetic IS state and they determine to a great extent the magnetic susceptibility. It is established that only 9% and 18% Co3+ ions in Bi1 − xLaxFe1 − xCoxO3 solid solutions (x = 0.9 or 0.8) are in the paramagnetic IS state in the temperature ranges of 5–30 and 5–110 K, respectively, while the other ions are diamagnetic.

Sw uobaghdad edu iqSynthesis and Characterization of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Hg(II) Complexes with Symmetrical Schiff base

New binuclear Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Hg(II) Complexes of N2S2 tetradentate or N4S2 hexadentate symmetric Schiff base were prepared by the condensation of butane-1,4-diylbis(2-amino ethylcarbamodithioate) with 3-acetyl pyridine. The complexes having the general formula [M2LCl4] (where L=butane-1,4-diyl bis (2-(z)-1-(pyridine-3-ylethylidene amino))ethyl carbamodithioate, M= Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Hg(II)), were prepared by the reaction of the mentioned metal salts and the ligand. The resulting binuclear complexes were characterized by molar conductance, magnetic susceptibility ,infrared and electronic spectral measurements. This study indicated that Mn(II), Ni(II) and Cu(II) complexes have octahedral geometry, while Co(II) Zn(II) and Hg(II) complexes are proposed to be tetrahedral structure .K

Sw uobaghdad edu iqSynthesis and Characterization of Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Hg(II) Complexes with Symmetrical Schiff base

New binuclear Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Hg(II) Complexes of N2S2 tetradentate or N4S2 hexadentate symmetric Schiff base were prepared by the condensation of butane-1,4-diylbis(2-amino ethylcarbamodithioate) with 3-acetyl pyridine. The complexes having the general formula [M2LCl4] (where L=butane-1,4-diyl bis (2-(z)-1-(pyridine-3-ylethylidene amino))ethyl carbamodithioate, M= Mn(II), Co(II), Ni(II), Cu(II), Zn(II), and Hg(II)), were prepared by the reaction of the mentioned metal salts and the ligand. The resulting binuclear complexes were characterized by molar conductance, magnetic susceptibility ,infrared and electronic spectral measurements. This study indicated that Mn(II), Ni(II) and Cu(II) complexes have octahedral geometry, while Co(II) Zn(II) and Hg(II) complexes are proposed to be tetrahedral structure .K

Some new transition metal complexes of bis (2-methyl furfuraldene)-4,4`-methylene bis (cyclohexylamine) ligand

New Fe(II),Co(II),Ni(II),Cu(II) and Zn(II) Schiff base complexes which have the molar ratio 2:1 metal to ligand of the general formula [M2( L) X4] (where L=bis(2-methyl furfuraldene)-4-4`-methylene bis(cyclo-hexylamine) ) were prepared by the reaction of the metal salts with the ligand of Schiff base derived from the condensation of 2:1 molar ratio of 2-acetyl furan and 4-4`-methylene bis (cyclohexylamine). The complexes were characterized by elemental analysis using atomic absorption spectrophotometer ,molar conductance measurements, infrared, electronic spectra,and magnetic susceptibility measurement. These studies revealed binuclear omplexes. The metal(II) ion in these complexes have four coordination sites giving the most expected tetrahedral structure and square planar for Cu(II)ion.

Some new transition metal complexes of bis (2-methyl furfuraldene)-4,4`-methylene bis (cyclohexylamine) ligand

New Fe(II),Co(II),Ni(II),Cu(II) and Zn(II) Schiff base complexes which have the molar ratio 2:1 metal to ligand of the general formula [M2( L) X4] (where L=bis(2-methyl furfuraldene)-4-4`-methylene bis(cyclo-hexylamine) ) were prepared by the reaction of the metal salts with the ligand of Schiff base derived from the condensation of 2:1 molar ratio of 2-acetyl furan and 4-4`-methylene bis (cyclohexylamine). The complexes were characterized by elemental analysis using atomic absorption spectrophotometer ,molar conductance measurements, infrared, electronic spectra,and magnetic susceptibility measurement. These studies revealed binuclear omplexes. The metal(II) ion in these complexes have four coordination sites giving the most expected tetrahedral structure and square planar for Cu(II)ion.

Structural analysis and magnetic properties of nanocrystalline NiCuZn ferrites synthesized via a novel gelatin method

In this study, nano-crystalline Ni0.6−xCuxZn0.4Fe2O4 ferrite (0.0⩽x⩽0.5) with grain sizes of 16–38nm have been prepared through a novel method using gelatin. The proper calcination temperature for the precursors which corresponding to the ferrites formation is estimated through thermal analysis measurement. X-ray diffraction patterns confirmed the formation of single phase cubic spinel structure. The grain size was estimated using transmission electron microscopy (TEM) technique. The lattice constant hardly changed with increasing copper concentration while the crystallite size increases. Fourier transform infrared spectra (FT-IR) indicate that the portion of Fe3+ ions at the tetrahedral sites move to the octahedral sites as some of the substituted Cu2+ ions get into the tetrahedral sites. The effect of Cu-substitution on the magnetic properties was studied through the temperature dependence of the molar magnetic susceptibility. The Curie temperatures (TC) were found to decrease with increasing the Cu concentration while molar magnetic susceptibilities remain constant.