Metal-spinel-corundum three phase equilibria in the system Ni-Cr-Al-O at 1373 K

The tie-lines representing the inter-crystalline ion exchange equilibria between the NiCr2O4-NiAl2O4 spinet solid solution and Cr2O3-Al2O3 corundum solid solution are determined by electron microprobe andEDAX pointcountanalysis of the oxide phases equilibrated with metallic Ni at 1373 K. The component activities in the spinet solid solution are derived from the tie-lines and thermodynamic data for Cr2O3-Al2O3 solid solution available in the literature. The Gibbs energy of mixing of the spinet solid solution calculated from the experimental data is discussed in relation to the values derived from the cation distribution models which assume random mixing of cations on both tetrahedral and octahedral sites. Positive deviation from the models is observed indicating significant positive enthalpy contribution arising form the size mismatch between Al+3 and Ni+2 ions on the tetrahedral site and Al+3, Ni+2 and Cr+3 on the octahedral site. Variation of the oxygen potential for threephase equilibrium involving metallic nickel, spinet solid solution and corundum solid solution is computed as a function of composition of the solid solutions at 1373 K. The oxygen potential exhibits a minimum at aluminum cationic fraction eta(Al)/(eta(Al) + eta(Cr)) = 0.524 in the oxide solid solutions.

Formation ranges of icosahedral, amorphous and crystalline phases in rapidly solidified Ti-Zr-Hf-Ni alloys

From the quaternary Ti-Zr-Hf-Ni phase diagram. the cross-section at 20 at % Ni was selected for investigation. The icosahedral quasicrystalline, crystalline and amorphous phases were observed to form in nine kinds of rapidly solidified (TixZryHfz)(80)Ni-20 (x + y + z = 1) alloys at different compositions. The quasilattice constants of 0.519 and 0.531 nm were obtained for the icosahedral phase formed in the melt-spun Ti40Zr20Hf20Ni20 and Ti20Zr40Hf20Ni20 alloys. respectively. The icosahedral phase formed in the melt-spun Ti40Zr20Hf20Ni20 alloy especially is thermodynamically stable. The supercooled liquid region of the Ti20Zr20Hf40Ni20 glassy alloy reached 64 K. From these results a comparison of quasicrystal-forming and glass-forming abilities, was carried out. The quasicrystal-forming ability was reduced and glass-forming ability was improved with an increase in Hf and Zr contents in the (TixZryHfz)(80)Ni-20 alloys. On the other hand. an increase in Ti content caused an improvement in quasicrystal-forming ability.

"Ni sit mä tajusin, et on muitakin kuin minä" : Suomenuskoisten sosiaalinen identiteetti

Työ on uskontososiologian tutkimusalaan lukeutuva laadullinen tapaustutkimus, joka perustuu argumentatiiviseen haastatteluaineistoon ja sosiaalisen identiteetin teoriaan. Tutkimuskysymys liittyy sosiaalisen identiteettiin. Miten suomenuskoinen hahmottaa oman yhteisönsä ja sen jäsenyyden? Mitä merkitystä yhteisöllä on suomenuskoiselle? Tutkimuksen aihepiiri on suomalainen uuspakanuus ja sen eräs suuntaus, suomenusko. Työn eräänä tarkoituksena on määritellä suomenuskon käsitettä ja sijoittaa suomenuskoinen suuntaus nykyajan suomalaisen uuspakanuuden kentälle. Hypoteesin mukaan suomenusko on uusiin uskontoihin lukeutuva uuspakanallinen liike. Se kuuluu ásatrún tavoin etnopakanuuden luokkaan, eli kansallisista muinaisperinteistä inspiraationsa ammentaviin suuntauksiin. Suomenuskolle on omalaatuista esikristillisten suomalaisten uskontoperinteiden sekä suomalaisen kansanuskon korostaminen lähteinä. Suomenuskon muut ominaispiirteet vastaavat tyypillistä uuspakanuutta: Luonnon ja perinteiden kunnioitus sekä epädogmaattisuus ja tasavertaisuus ovat keskeisiä arvoja. Työ tehtiin puolistrukturoituna haastattelututkimuksena. Seitsemää suomenuskoista haastateltiin laadullisen asennetutkimuksen menetelmän mukaisesti. Menetelmä on uudehko ja kiinnostava. Se perustuu argumentatiivisen haastatteluaineiston tuottamiseen väittämäkorttien avulla. Analyysissä haastatteluaineistosta paikannetaan asenteita, eli subjektin ilmaisemaa jonkin kohteen arvottamista. Asenteista pyrittiin löytämään ulkoryhmiin kohdistuvia vertailuja ja retorisia erottautumisia. Työn teoreettisena tukirankana on Henri Tajfelin ja John C. Turnerin kehittämä sosiaalisen identiteetin teoria. Teorian mukaan sosiaalista identiteettiä on mahdollista tutkia ainoastaan sosiaalisten ryhmien keskinäisen vertailun asetelmassa. Omia sisäryhmiä vertaillaan aina ulkoryhmiin siten, että oma ryhmä näyttäytyy voittajana. Tämä takaa yksilölle myönteisen omanarvontunnon. Karmela Liebkindin mukaan vähemmistöryhmät vertailevat itseään valtakulttuurin enemmistöryhmiin. Heikki Pesosen ja Elina Huhdan mukaan vähemmistöuskonnot pyrkivät oikeuttamaan omaa uskontoaan tekemällä omalle ryhmälle suotuisia vertailuja. Tutkimuksessa havaittiin haastateltavien tekemiä retorisia erottautumisia ulkoryhmistä sekä heidän ilmaisemiaan asenteita, jotka liittyvät suomenuskoisten sisäryhmän dynamiikkaan. Tulosten perusteella haastatellut suomenuskoiset erottautuvat ryhmänä muusta uuspakanuudesta ja vielä selvemmin New Agesta ja satanismista, jotka eivät ole uuspakanuutta. Lisäksi haastateltavat korostavat eroa dogmaattisiin valtauskontoihin, varsinkin evankelis-luterilaisen valtionkirkon enemmistöryhmään. Suomenuskoisten yhteisöön liittymisen prosessin havaittiin muistuttavan sosiaalista itsekategorisointia yhteisön jäsenyydessä ratkaiseva tekijä on oman jäsenyyden tajuaminen itse. Teorian mukaan tämä johtaa sosiaalisen identiteetin muodostumiseen ja siten ryhmäkäyttäytymiseen. Haastateltavilla oli havaittavissa vahva sosiaalinen identiteetti. Uuspakanuuden kenttään suhteutettuna se oli poikkeuksellisen yhtenäinen. Lisäksi selvisi, että suomenuskoiset suunnittelevat uskonnolliseksi yhdyskunnaksi rekisteröitymistä.

Competing magnetic interactions in a dinuclear Ni(II) complex: Antiferromagnetic O-H center dot center dot center dot O moiety and ferromagnetic N-3(-) ligand

Synthesis, structural characteristics, magnetic studies and DFT calculations in Ni(II) dinuclear complexes containing two bridging N-3(-) and an O-(HO)-O-... linkage reveal the existence of ferromagnetic interactions between Ni(II) centers via N-3(-) ligands and antiferromagnetic interactions through the H-bonded moiety. The overall magnetic behavior of the system depends on the delicate balance between these two competing interactions.

Characterization of Alloy-Spinel-Corundum Equilibrium in the System Fe-Ni-Al-O

The three phase equilibrium between alloy, spinel solid solution and α-alumina in the Fe-Ni-Al-O system has been fully characterized at 1823K as a function of alloy composition using both experimental and computational methods. The oxygen potential was measured using a solid state cell incorporating yttria-doped thoria as the electrolyte and Cr+ Cr2O3 as the reference electrode. Oxygen concentration of the alloy was determined by an inert gas fusion technique. The composition of the spinel solid solution, formed at the interface between the alloy and an alumina crucible, was determined by EPMA. The variation of the oxygen concentration and potential and composition of the spinel solid solution with mole fraction of nickel in the alloy have been computed using activities in binary Fe-Ni system, free energies of formation of end member spinels FeO•(1+x)Al2O3 and NiO•(1+x)Al2O3 and free energies of solution of oxygen in liquid iron and nickel, available in the literature. Activities in the spinel solid solution were computed using a cation distribution model. The variation of the activity coefficient of oxygen with alloy composition in Fe-Ni-O system was calculated using both the quasichemical model of Jacob and Alcock and the Wagner's model, with the correlation of Chiang and Chang. The computed results for the oxygen potential and the composition of the spinel solid solution are in good agreement with the measurements. The measured oxygen concentration lies between the values computed using models of Wagner and Jacob and Alcock. The results of the study indicate that the deoxidation hyper-surface in multicomponent systems can be computed with useful accuracy using data for end member systems and thermodynamic models.

An in situ EXAFS investigation of bimetallic Cu---Ni/γ-Al2O3 catalysts

In situ EXAFS investigations have been carried out on Ni/γ-Al2O3 and Cu---Ni/γ-Al2O3 catalysts with different metal loadings, and prepared by different procedures. As-prepared Ni/γ-Al2O3 on calcination gives NiO and NiAl2O4-like phases on the surface, the proportion of the latter increasing with the increase in calcination temperature; the proportion of the NiO-like phase, on the other hand, increases with the metal loading. The reducibility of Ni/γ-Al2O3 to give metallic Ni on the surface directly depends on the proportion of the NiO-like phase present before reduction. Co-impregnating with Cu suppresses the formation of the surface aluminate and thereby favours the reduction to metallic Ni. This conclusion is clearly substantiated by our studies of bimetallic catalysts containing varying Cu/Ni ratios and also those prepared by the two-stage impregnation procedure.

Preparation, characterization, spectral and thermal analyses of (N2H5)2MCl4·2H2O (M = Fe, Co, Ni and Cu); crystal structure of the iron complex

Hydrazinium metal chlorides, (N2H5)2MCl4·2H2O (where M = Fe, Co, Ni and Cu), have been prepared from the aqueous solutions of the respective metal chlorides and hydrazine hydrochloride (N2H4·HCl or N2H4·2HCl) and investigated by spectral and thermal analyses. The crystal structure of the iron complex has been determined by direct methods and refined by full-matrix least-squares to an R of 0.023 and Rw of 0.031 for 1495 independent reflections. The structure shows ferrous ion in an octahedral environment bonded by two hydrazinium cations, two chloride anions and two water molecules. In the complex cation [Fe(N2H5)2(H2O)2Cl2]2+, the coordinated groups are in trans positions.

Reactivity with hydrogen of pure iron oxide and of iron oxides doped with oxides of Mn, Co, Ni and Cu

Using dynamic TG in H2, X-ray powder diffraction and Mössbauer Spectroscopy the reactivities fot hydrogen reduction of Fe2O3 prepared at different temperatures, Fe2O3 doped with oxides of Mn, Co, Ni and Cu prepared at 300DaggerC from nitrate precursors and intermediate spinels derived from above samples during reduction have been explored. The reactivity is higher for finely divided Fe2O3 prepared at 250DaggerC. The reduction is retarded by Mn, marginally affected by Co and accelerated by Ni and Cu, especially at higher (5 at.%) dopant concentration. These reactivities confirmed also by isothermal experiments, are ascribed to the nature of disorder in the metastable intermediate spinels and to hydrogen rsquospill overrsquo effects.

A formate bridged Ni(II) sheet and its 3D analogue in presence of a linear organic linker: Synthesis, crystal structure and magnetic properties

Reaction of formamide with Ni(NO3)(2)center dot 6H(2)O under hydrothermal condition in a mixture of MeOH/H2O forms a two-dimensional formate bridged sheet Ni(HCOO)(2)(MeOH)(2) (1). X-ray structure analysis reveals the conversion of formamide to formate which acts as a bridging ligand in complex 1 where the axial sites of Ni(II) are occupied by methanol used as a solvent. An analogous reaction in presence of 4,4'-bipyridyl (4,4'-bipy) yielded a three-dimensional structure Ni(HCOO)(2)(4,4'-bpy) (2). DC magnetic measurements as a function of temperature and field established the presence of spontaneous magnetization with T-c (Curie temperature) = 17 and 20.8 K in 1 and 2, respectively, which can be attributed due to spin-canting. DFT calculations were performed to corroborate the magnetic results of 1 and 2. (C) 2010 Elsevier Ltd. All rights reserved.