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Cation Distribution in Co0.7Me0.3Fe2O4 (Me = Zn, Ni and Mn)  [PDF]
A. Mahesh Kumar, P. Appa Rao, M. Chaitanya Varma, Gsvrk Choudary, K. H. Rao
Journal of Modern Physics (JMP) , 2011, DOI: 10.4236/jmp.2011.29132
Abstract: Co0.7Me0.3Fe2O4 (Me = Zn, Ni and Mn) were synthesized through co-precipitation method. Cationic distribution for these ferrites was proposed on the basis of magnetization measurements and available occupancy of the substituent ions into the spinel lattice. Theoretical lattice constant calculations confirm the proposed cationic distributions were the correct ones.
Crystalline structure of the manganites solid solution RE(Me,Mn)O3, (RE=Gd,Er; Me=Ni,Co)  [cached]
Moure, C.,Tartaj, J.,Moure, A.,Pe?a, O.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2009,
Abstract: The structural properties of the manganites solid solution RE(Me,Mn)O3, RE=Er,Gd, have been studied by X-ray diffraction and electric measurements. Powders were prepared by solid state reaction between the component oxides. Incorporation of Ni2+ or Co2+ on the lattice in the Mn sites leads to changes in the parameters and symmetry of the perovskite or hexagonal compounds GdMnO3 and ErMnO3 respectively. The phase transitions depend on the amount of substituted Jahn-Teller Mn3+ cations, and, therefore, of the cooperative Jahn-Teller interaction weakness. Solid solutions based on GdMnO3 perovskite compound change from O’-type to O-type orthorhombic perovskite symmetry when the Mn3+ cation amount decreases, because of the progressive substitution for Ni, Co. This transition occurs for lower amount of Ni2+ than for Co2+ cation. The Er-based solid solutions showed a different behaviour. For Ni2+ and Co2+ incorporation there are changes from hexagonal ErMnO3-type lattice to perovskite-type symmetry, for 20 at% and 30 at% respectively of substituting cations. The resultant perovskites crystallised directly in the O-type orthorhombic perovskite structure. The steric influence seems to play a secondary role, such as it can be deduced of the small variation of the Goldschmidt tolerance factor, t, for perovskite structure. Las propiedades estructurales de las soluciones sólidas RE(Me,Mn)O3, RE=Gd,Er, Me=Ni,Co, han sido estudiadas por difracción de rayos X, (DRX) y medidas eléctricas. Las fases se sintetizaron por reacción en estado sólido entre los óxidos componentes. La incorporación de los cationes Ni2+ y Co2+,3+ en la red en lugar de Mn lleva a cambios en los parámetros de red y en la simetría de la perovskita, GdMnO3 o del compuesto hexagonal ErMnO3 respectivamente. Las transiciones de fase dependen de la cantidad de Mn3+ sustituido, y por tanto de la debilitación del efecto co-operativo Jahn-Teller. Las soluciones sólidas basadas en GdMnO3 cambian de perovskita tipo O’ a perovskita tipo O. Esta transición ocurre para una menor cantidad de Ni que para Co como sustituyentes. Las soluciones basadas en ErMnO3 muestran un comportamiento algo diferente: la incorporación induce cambios desde la estructura hexagonal a una estructura tipo perovskita en la forma O, para cantidades de ~20 at% Ni y para ~30 at% Co. La influencia del factor estérico en las transiciones observadas parece jugar un papel secundario frente a la desaparición progresiva de los cationes Jahn-Teller Mn3+.
Spin reversal in Gd(Me,Mn)O3 (Me = Co, Ni)  [cached]
Pe?a, O.,Ghanimi, K.,Moure, C.,Gutiérrez, D.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2004,
Abstract: Partial substitution of the rare-earth by calcium at the cationic site of the ABO3 perovskites may show extraordinary effects of spin reversal due to a negative polarization between the rare-earth and the manganese networks, as it occurs in the solid solution Gd1 xCaxMnO3. We present herein similar effects in gadolinium perovskites of the Gd(Me,Mn)O3 type, in which the manganese sublattice has been partially substituted by transition metal elements Me, leaving the gadolinium network intact. The spin reversal phenomena is observed at a critical concentration of x(Me) = 1/3, which implies an optimum number of pairs Mn3+-Mn4+. Néel temperatures of 48 and 67 K are obtained for Me = Co and Ni, respectively, at the optimum concentration of substituent. A comparison between these different solid solutions allows us to generalize the interpretation of two interacting magnetic sublattices : a Mn-based ferromagnetic one and a negatively-aligned gadolinium network. La sustitución parcial del lantánido por el elemento calcio en el sitio catiónico (sitio A) de la perovskita ABO3 puede dar lugar a efectos importantes ligados a una inversión del espín. Dicha inversión se debe a una interacción negativa entre la tierra rara y la subred de manganeso, tal como ocurre en la solución solida Gd1-xCaxMnO3. Se presentan en este trabajo efectos similares que ocurren en las perovskitas de gadolinio de fórmula Gd(Me,Mn)O3, en las cuales la subred de manganeso (sitio B) ha sido reemplazada parcialmente por otros metales de transición Me, dejando intacta la subred de gadolinio. Se observa el fenómeno de inversión de espín para una concentración crítica x(Me) = 1/3, para la cual se logra una cantidad óptima de pares Mn3+ Mn4+. Para esta concentración crítica se observan temperaturas de Néel antiferromagnéticas del orden de 48 y 67 K, respectivamente para Me = Co y Ni. Un análisis comparativo entre estos diferentes sistemas permite generalizar la interpretación de la existencia de dos subredes magnéticas que interactúan : una subred ferromagnética relacionada con el Mn, y una subred de gadolinio cuyos espines se orientan en sentido contrario a la primera.
Cation distribution of Ni0.5Zn0.5Fe2O4 nanoparticles
Rakesh K Singh, Chandan Upadhyay, Samar Layek, A Yadav
International Journal of Engineering, Science and Technology , 2010,
Abstract: A set of Ni0.5Zn0.5Fe2O4 samples were prepared by citrate precursor route to investigate the growth mechanism and its effect on cationic distribution. Following the information from DTA–TGA analysis, samples were annealed at 550 °C, 700 °C and 750 °C. Magnetization and M ssbauer studies suggest that initially the cationic distribution deviates from its normal preferences but it gets back to the normal preference at a temperature around 675 °C. It has been found that size onset for having the bulk cation configuration exclusively depends on the composition.
Influence of Ni/Mn cation order on the spin-phonon coupling in multifunctional La2NiMnO6 epitaxial films by polarized Raman spectroscopy  [PDF]
K. D. Truong,M. P. Singh,S. Jandl,P. Fournier
Physics , 2009, DOI: 10.1103/PhysRevB.80.134424
Abstract: We report the influence of Ni/Mn ordering on the spin-phonon coupling in multifunctional La2NiMnO6. Three types of films with different levels of structural order, including long-range Ni/Mn cation order, cation disorder, and an admixture of the ordered and disordered phases, are compared by polarized micro-Raman spectroscopy and magnetometry. Each film displays a strong dependence on the polarization configuration and a unique set of Raman active phonon excitations. Long-range cation ordering results in the splitting of Raman active phonon peaks because of Brillouin zone folding and lowering symmetry. Phonon mode softening begins clearly at a distinct temperature for each sample revealing a strong spin-lattice interaction. It follows closely the magnetization curve in ordered films. Unlike the admixture and the ordered films, softening behavior is strongly suppressed in the cation-disordered films. These differences may be understood based on the variation in amplitude of the spin-spin correlation functions due to the local Ni/Mn cation ordering.


物理学报 , 1958,
Abstract: Faraday rotation and loss characteristics at 9200 me and at room temperature of Ni-Mg, Mg-Mn and Ni-Zn ferrite rods and disks placed in a circular waveguide are measured as a function of applied longitudinal DC magnetic field.Of particular interest are the results obtained with a new type of Ni-Mg ferrites, since very little data on Ni-Mg ferrites have been published in the literature. In this paper sufficient data are given on Faraday rotation and loss characteristics of a complete range of nickel-magnesium ferrites with composition varying from pure nickel to pure magnesium. Experimental results at 9200 me indicate that for the sintering temperature of 1300℃, the best composition range for nickel-magnesium ferrites would be Ni0.7Mg0.3Fe2O4-Ni0.8Mg0.2Fe2O4. In future, nickel-magnesium ferrites, due to their very low loss, may find practical applications in the microwave field.Comparison information as to the relative merits of these three useful microwave ferrites are given in the form of curves and tables, and their results are discussed in some detail.This paper also gives a summary of the linear theory on Faraday rotation of a linearly polarized wave propagating in ferrite-loaded waveguide which is longitudinally magnetized.
Effect of Sewage Sludge, Compost and Cow Manure on Growth and Yield and Fe, Zn, Mn and Ni Uptake in Tagetes Flower  [cached]
M. Sharifi,M. Afyuni,A. H. Khoshgoftarmanesh
Journal of Science and Technology of Greenhouse Culture , 2010,
Abstract: A pot experiment was conducted in Isfahan University of Technology research greenhouse to investigate the effects of sewage sludge, compost and cow manure on growth and uptake of Fe, Zn, Mn and Ni in tagetes flower. A completely randomized research with three treatments (sewage sludge, compost and cow manure at 25 Mg ha-1) and three replicates was performed. Application of organic wastes significantly increased organic matter and CEC of the soil. Application of compost significantly increased DTPA-extractable Fe, Zn, Mn and Ni of the soil. The use of organic wastes increased tagetes flower growth. The growth of plant was highest in the compost treatment. Results indicated that Fe, Zn, Mn and Ni uptake by plant shoot, and the percentage of metals translocated to the shoot was greater in the compost treatment compared to other treatments. In general, the application of compost for tagetes flower had a positive impact on plant growth parameters and micronutrients uptake.
Electronic Structure of Transition-Metal Dicyanamides Me[N(CN)$_2$]$_2$ (Me = Mn, Fe, Co, Ni, Cu)  [PDF]
D. O. Demchenko,Amy Y. Liu,E. Z. Kurmaev,L. D. Finkelstein,V. R. Galakhov,A. Moewes,S. G. Chiuzbaian,M. Neumann,Carmen R. Kmety,Kenneth L. Stevenson
Physics , 2003, DOI: 10.1103/PhysRevB.69.205105
Abstract: The electronic structure of Me[N(CN)$_2$]$_2$ (Me=Mn, Fe, Co, Ni, Cu) molecular magnets has been investigated using x-ray emission spectroscopy (XES) and x-ray photoelectron spectroscopy (XPS) as well as theoretical density-functional-based methods. Both theory and experiments show that the top of the valence band is dominated by Me 3d bands, while a strong hybridization between C 2p and N 2p states determines the valence band electronic structure away from the top. The 2p contributions from non-equivalent nitrogen sites have been identified using resonant inelastic x-ray scattering spectroscopy with the excitation energy tuned near the N 1s threshold. The binding energy of the Me 3d bands and the hybridization between N 2p and Me 3d states both increase in going across the row from Me = Mn to Me = Cu. Localization of the Cu 3d states also leads to weak screening of Cu 2p and 3s states, which accounts for shifts in the core 2p and 3s spectra of the transition metal atoms. Calculations indicate that the ground-state magnetic ordering, which varies across the series is largely dependent on the occupation of the metal 3d shell and that structural differences in the superexchange pathways for different compounds play a secondary role.
Teores de Fe, Mn, Zn, Cu, Ni E Co em solos de referência de Pernambuco
Biondi, Caroline Miranda;Nascimento, Clístenes Williams Araújo do;Fabricio Neta, Adelazil de Brito;Ribeiro, Mateus Rosas;
Revista Brasileira de Ciência do Solo , 2011, DOI: 10.1590/S0100-06832011000300039
Abstract: heavy metals are a group of elements with specific features and natural occurrence in the environment, representing an accessory in the formation of rocks. these elements, although associated with toxicity, must be treated different from xenobiotics, since many metals are evidentially essentials (fe, mn, cu, zn, and ni) and beneficial (co) for plants. in this context, the objective was to determine the natural contents of the metals iron (fe), manganese (mn), zinc (zn), nickel (ni), copper (cu) and cobalt (co) in benchmark soils of pernambuco. soil samples were collected in the three physiographic regions of the state (zona da mata, agreste and sert?o), in the first two horizons of the 35 benchmark soils of the state of pernambuco. sample digestion was based on the method 3051a (usepa, 1998) and determined by icp-oes. significant correlations were found between these metals and those with the clay soil fraction in both horizons, indicating the general association of most metals to the most clayey soils. the fe, mn, zn, cu, ni, and co contents of most soils were lower than in soils from other regions of the country and more mafic lithology, which confirms that the contents of these elements are more directly related to iron-magnesium minerals. the results indicate a low capacity of the soils of pernambuco to release cu, co and ni to plants, while deficiencies of zn, fe and mn are less likely. the natural contents of fe, mn, zn, cu, ni, and co determined here can be used as a basis for defining the quality reference values for soils of pernambuco, as stipulated by the brazilian legislation.
Operational speciation of Cd, Cr, Cu, Mn, Ni, Pb, V and Zn in dust samples from schools in Caracas, Venezuela
Atmósfera , 2008,
Abstract: a sequential extraction approach has been applied to analyze cd, cr, cu, mn, ni, pb, v and zn in dust samples from different schools chosen according with their location in areas with different concentrations of total suspended particles (tsp). the aim of this work is to provide information about the chemical fractionation of metal content. hence, information about the origin, mode of occurrence, mobilization and transport of metals could be obtained. total and partial metal concentrations were further determined by analyzing the samples after acid digestion procedure. the results compare very well for both methods. the metals are associated with various chemical forms as distinguished by sequential chemical extraction. the carbonate and fe-mn oxide phases dominate for pb, zn and cu, whereas for ni the organic phase is most important. v, mn, cr, cd are mainly present in the oxide phases, however they are too in a residual phase but in minor proportion. the different sources for the elements studied are supported by the results from multivariate (pca) analysis.
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