Partition of Microamounts of Some M2+ Ions During MgSO4.7H2O Crystallization

1999 ◽  
Vol 52 (6) ◽  
pp. 425 ◽  
Author(s):  
Marek Smolik
Keyword(s):  
Solid Solutions ◽  
Partition Coefficients ◽  
Ionic Radii ◽  
D Values

Partition coefficients (D) of trace amounts of Ni2+, Co2+, Zn2+, Cd2+, Cu2+, Mn2+, Ca2+, and Fe2+ have been determined during crystallization of MgSO4.7H2O. Their dependences on the ionic radii of the M2+ ions, solubilities and structures of the corresponding sulfates, as well as the abilities of the microcomponents to form solid solutions with MgSO4.7H2O have been analysed. The D values are in the range from <0·005 (DCa) to 1·13 (DNi) and depend mainly on the ionic radii of the M2+ ions, as well as the structures of the corresponding sulfates and the ability to form solid solutions with the macrocomponent.

Distribution of microamounts of some M2+ ions during ZnSO4·7H2O crystallization

2000 ◽  
Vol 78 (7) ◽  
pp. 993-1002 ◽  
Author(s):  
Marek Smolik
Keyword(s):  
Solid Solutions ◽  
Ionic Radius ◽  
Electronic Configuration ◽  
Distribution Coefficients ◽  
Octahedral Coordination ◽  
Crystal Chemical ◽  
Trace Impurities ◽  
Ionic Radii ◽  
Sulfate Heptahydrate ◽  
D Values

Distribution coefficients (D) of trace amounts of Ni2+, Co2+, Mg2+, Cd2+, Cu2+, Mn2+, Ca2+, and Fe2+ have been determined during crystallization of ZnSO4·7H2O. Their dependencies on the ionic radii of M2+ ions, solubilities and structures of the corresponding sulfates as well as their abilities to form solid solutions with ZnSO4·7H2O have been analyzed. The D values are in the range <0.006 (DCa) - 1.61 (DNi) and depend mainly on similarity of the structures of the corresponding sulfates and the ability of MSO4·nH2O to form solid solutions with ZnSO4·7H2O. The order of lowering some of the determined distribution coefficients (DNi > DMg > DCo > DFe > Dcu) exactly agrees with increase of the deformation trend of octahedral coordination of corresponding ions resulting from their electronic configuration. The D coefficients do not depend on similarity of size of ionic radii of microcomponent (rM2+) to macrocomponent (rZn2+), however for ions forming monoclinic sulfate hydrates at 20°C (Co2+, Fe2+, Cd2+, Ca2+) this dependence of distribution coefficients on rM2+ is linear in a plot of log D against ionic radius. The effect of solubilities of corresponding sulfates in water on the D coefficients is complex and clouded by crystal-chemical factors.Key words: crystallization, zinc(II) sulfate heptahydrate, cocrystallization, distribution coefficients D (Henderson-Kracek, Khlopin), distribution of trace impurities.

Microstructure and Properties of Lead-Free Perovskite Ceramics on the Base of KNN Perovskite

2020 ◽  
Vol 27 ◽  
pp. 90-98
Author(s):  
E.D. Politova ◽  
G.M. Kaleva ◽  
Alexander V. Mosunov ◽  
N.V. Sadovskaya ◽  
Dmitry A. Kiselev ◽  
...  
Keyword(s):  
Solid Solutions ◽  
Piezoelectric Coefficient ◽  
Piezoelectric Properties ◽  
Unit Cell ◽  
Lead Free ◽  
Unit Cell Parameters ◽  
Ionic Radii ◽  
Cell Parameters ◽  
Microstructure And Properties ◽  
Perovskite Ceramics

The influence of LiSbO3 on the structure, microstructure, dielectric, ferroelectric and local piezoelectric properties of (K0.5Na0.5)NbO3 ceramics has been studied. Changes in unit cell parameters correlated with ionic radii changes and high effective local d33 piezoelectric coefficient values were observed depending on solid solutions compositions.

scholarly journals The lattice spacings of solid solutions of different elements in aluminium

1948 ◽  
Vol 193 (1032) ◽  
pp. 1-24 ◽  
Keyword(s):  
Solid Solution ◽  
Solid Solutions ◽  
Lattice Spacing ◽  
Relative Volume ◽  
Valency Electron ◽  
Vegard’S Law ◽  
Copper Zinc ◽  
Composition Curve ◽  
The Difference ◽  
D Values

Measurements have been made of the lattice spacings of solid solutions of lithium, magnesium, silicon, copper, zinc, germanium and silver in aluminium. The lattice of aluminium is expanded by the solution of magnesium or germanium, and contracted by the solution of lithium, silicon, copper or zinc. No change in lattice spacing can be detected when silver is dissolved in aluminium, although microscopic examination shows that a solid solution is formed, and this is confirmed by the absence of any diffraction lines other than those of the solid solution in aluminium. If the lattice spacing/composition curve for dilute solutions is extrapolated to 100% of solute, the resulting lattice spacing refers to a hypothetical face-centred cubic modification of the solute, and the corresponding closest distance of approach of the atoms is called the apparent atomic diameter (A. A. D.) of the solute when in solution in aluminium. Previous work enables the corresponding A. A. D. values to be deduced for the above solute elements when dissolved in univalent copper, silver or gold, and in divalent magnesium. The differences between the A. A. D. values of a given element when dissolved in various solvents are discussed, and it is suggested that they are controlled by the interplay of four factors: (1) the relative volume per valency electron in crystals of the solvent and solute, (2) the relative radii of the ions of solvent and solute, (3) Brillouin zone effects, and (4) the difference between solvent and solute in the electrochemical series. If this line of approach adopted be correct, it follows that it is only in exceptional circumstances that the so-called Vegard’s law will apply to metallic solid solutions.

Crystal chemical incorporation of high level waste species in aluminotitanate-based ceramics: Valence, location, radiation damage, and hydrothermal durability

1987 ◽  
Vol 2 (3) ◽  
pp. 387-414 ◽  
Author(s):  
P. E. Fielding ◽  
T. J. White
Keyword(s):  
Solid Solutions ◽  
High Level Waste ◽  
Crystal Chemical ◽  
Extended Defects ◽  
Ionic Radii ◽  
Space Groups ◽  
Atomic Displacements ◽  
Compositional Variations ◽  
High Level ◽  
Induced Changes

A compilation is made of the crystallographic mechanisms whereby (simulated) radwaste species are incorporated in the “synroc” phases zirconolite, perovskite, hibonite, and “hollandite.” From these data and consideration of the crystal chemical criteria of valence and effective ionic radii, the most probable host phases for transuranic isotopes are identified. The distinction is drawn between incorporation of radwaste species as dilute homogeneous, continuous solid solutions and as heterogeneous, noncontinuous solid solutions. It is shown that compositional variations at the nanometer level are frequently accompanied by the generation of new interstices within extended defects, which are suitable for the location of radwaste. Nuclides that are unstable towards beta and gamma decay lead to transmutation-induced changes in stoichiometry. Crystallochemical mechanisms that minimize structural disruption during the formation of radiogenic species are discussed. Thermally promoted recovery of metamict phases, which were rendered aperiodic by direct atomic displacements of alpha-recoil nuclei, are examined in terms of recrystallization via the hierarchial arrangement of space groups. An evaluation is made of the hydrothermal durability of synroc phases under conditions likely to be experienced by the wasteform should the repository be breached by groundwaters shortly after disposal.

scholarly journals Absence of solid solution between Fe(II) and Mg(II) hydroxides and consequences on formation of fougerite and smectites

2019 ◽  
Vol 98 ◽  
pp. 04003
Author(s):  
Guilhem Bourrié ◽  
Jihaine Ben Nacib ◽  
Georges Ona-Nguema ◽  
Fabienne Trolard
Keyword(s):  
Solid Solution ◽  
Aqueous Solution ◽  
Solid Solutions ◽  
Electric Charge ◽  
Ionic Radii

As there exists extended solid solutions between ferrous and magnesian silicates, experiments were conducted to check if ferrous and magnesian hydroxides can co-precipitate in a solid solution. Results show that no solid solution forms and instead Fe(II) and Mg(II) hydroxides precipitate separately with the same solubilities as pure components. However, in fougerite, F(III), Fe(II) and Mg(II) coexist in a brucitic type hydroxide, with an extended solid solution. This implies that fougerite formation results from Fe(III) precipitation, Fe(III) being surrounded by divalent Fe(II) and Mg(II) to comply with the exclusion rule: Fe(III) ions cannot be direct neighbours. Consequently, Fe(III) - Fe(II) - Mg(II) smectites cannot form by oxidation of a ferrous magnesian brucitic layer, but by silication of fougerite. The impossibility of formation of a solid solution between Fe(II) hydroxide and Mg(II) hydroxide, while their electric charge and ionic radii are identical can be explained by the differences of electronegativities of the elements. Fe(II) and Mg(II) can dimerize separately in aqueous solution, but an heterodimer cannot form.

Modeling differentiation in igneous systems: On the importance of considering temperature & composition dependent partition coefficients

2021 ◽  
Author(s):  
Aurore Toussaint ◽  
Lydéric France
Keyword(s):  
Partition Coefficients ◽  
Thermal Evolution ◽  
Experimental Studies ◽  
Thermodynamic Models ◽  
New Approach ◽  
First Order ◽  
Chem Geol ◽  
Mineral Phases ◽  
Order Of Magnitude ◽  
D Values

&lt;p&gt;&amp;#160; &amp;#160; &amp;#160; &amp;#160;Studying magma reservoir processes is one of the keys to understand the evolution of igneous systems. One of the main processes, magma differentiation, governs the thermal evolution and chemical composition of the melt-crystal assemblage (magma or mush depending on the relative proportions), and therefore exerts a first order control over its physical properties (density, viscosity), and thus on reservoir dynamics. Various approaches have been implemented to model differentiation in an attempt to benchmark all the involved variables like initial and phase compositions, temperature, pressure, and oxygen fugacity (C&lt;sub&gt;0&lt;/sub&gt;, X, T, P, &lt;em&gt;f&lt;/em&gt;O&lt;sub&gt;2&lt;/sub&gt;). Those approaches are among others mass balance calculations considering partition coefficients (D) values, experimental studies, thermodynamic models or a combination of those. In any of those cases, the evolution of trace elements is governed by the value of the D that is known to be dependent on (P, T, X, &lt;em&gt;f&lt;/em&gt;O&lt;sub&gt;2&lt;/sub&gt;). However, most of the present-day studies still use fixed values of D to provide first order estimates.&lt;/p&gt;&lt;p&gt;&amp;#160; &amp;#160; &amp;#160; Here, we present an approach combining thermodynamic modeling (relying on Rhyolite-MELTS, Gualda et al., 2012), that integrates X-T-P-&lt;em&gt;f&lt;/em&gt;O&lt;sub&gt;2&lt;/sub&gt;-dependent D for Rare Earth Elements (REE). We applied this new approach to a MORB system, with olivine, clinopyroxene and plagioclase as main mineral phases, and compared results to more classical approaches. D are derived from the models of Sun &amp; Liang (2012, 2013, 2014) and Sun et al. (2017). The resulting model highlights that T &amp; X effects on the D values can add or counterbalance each other depending on the mineral considered. In any cases our results emphasize the gain of using thermodynamic models along with both T- &amp; X-dependent D values to properly model the evolution of igneous systems. Relying on our results, and on the corresponding thermodynamics constraints, we were also able to provide D for any mineral composition crystallized from this MORB system. Results bring to light that an error of ~1 order of magnitude of the D&lt;sup&gt;mineral-melt&lt;/sup&gt; value could be introduced when considering a fixed value of D.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Gualda et al. (2012) &lt;em&gt;Journal of Petrology&lt;/em&gt;, 53-5, 875-890; Sun &amp; Liang (2012) &lt;em&gt;Contrib Mineral Petrol&lt;/em&gt; 163-5: 807-823; (2013) &lt;em&gt;Chem Geol&lt;/em&gt; 358: 23-36; (2014) &lt;em&gt;Chem Geol&lt;/em&gt; 372: 80-91; Sun et al. (2017) &lt;em&gt;Geochim Cosmochim Acta&lt;/em&gt; 206: 273-295.&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;

Improvement of Fluorite Structures in M203-CeO2 (M=Sm, La) System Based on a Novel Effective Index

1998 ◽  
Vol 548 ◽  
Author(s):  
Toshiyuki Mori ◽  
Takayasu Ikegami ◽  
Hiroshi Yamamura
Keyword(s):  
Ionic Conductivity ◽  
Solid Solutions ◽  
Ionic Conduction ◽  
Fluorite Structure ◽  
Effective Index ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Ionic Radii ◽  
Order Of Magnitude ◽  
Oxide Ionic Conductivity

ABSTRACTM2O3-CeO2(M=Sm, La) system is one of the most interesting of fluorite oxides since the oxide ionic conductivity of it is higher than that of yttria-stabilized zirconia. In this study, the effective index for the improvement of ionic conductivity in CeO2 systems was defined using information regarding ionic radii and the level of oxygen vacancies from the perspective of crystallography. It is assumed that the M2O3 CeO2 based oxides approach the ideal fluorite structure for fast ionic conduction when the effective index increases toward 1. A small amount of alkali- or alkali-earth doped M2O3-CeO2 (M=Sm, La) solid solutions were prepared based on this effective index. The oxide ionic conductivity increased with an increase of this effective index. (La0.75Sr0.2Ba0.05)0.175 Ce0.825 O1.89 that had high effective index, showed high oxide ionic conductivity over the order of magnitude in comparison with 8mol% yttria-stabilized zirconia. Moreover, the oxygen partial pressure dependence of oxide ionic conductivity of M2O3-CeO2(M=Sm, La) solid solutions was improved by the increasing effective index. The utility of this effective index, for improvement of the electrical properties in fluorite CeO2 based materials, was investigated.

Mineral/melt partition coefficients of oceanic alkali basalts determined on natural samples using laser ablation-inductively coupled plasma-mass spectrometry (LAM-ICP-MS)

2000 ◽  
Vol 64 (1) ◽  
pp. 85-94 ◽  
Author(s):  
G. M. Thompson ◽  
J. Malpas
Keyword(s):  
Trace Elements ◽  
Trace Element ◽  
Inductively Coupled Plasma ◽  
Partition Coefficients ◽  
Dominant Factor ◽  
Alkali Basalts ◽  
Compositional Evolution ◽  
Icp Ms ◽  
D Values ◽  
The Impact

AbstractIn order to limit the range of possible differentiation mechanisms and the impact of these processes on the trace element signatures of igneous suites, it is important to be able to predict or model the compositional evolution of the primary and/or parental magmas. Part of the problem in understanding these relationships in basalts from ocean islands is the paucity of reliable trace element mineral/melt partition coefficients, particularly for undersaturated magmas. Consequently, we have measured mineral/groundmass partition coefficients for Rb, Sr, Y, Zr, Nb, Hf, Ta, Th and REE, in situ, in clinopyroxene, Fe-Ti oxides and olivine in primitive basalts from Rarotonga, Cook Islands using LAM-ICP-MS.Analyses of these mafic rocks show high concentrations of most incompatible trace elements (e.g. Sr, Th, Y, REE, etc.) in pyroxenes relative to the other phases, suggesting that fractionation of pyroxenes was the dominant factor in the distribution of these trace elements during crystal fractionation. In such cases, the highly incompatible elements (D <0.01) are Ba, Cs and Nb. Elements that could also be classified as strongly incompatible (D <0.1) are Rb, Ta and Th. The remaining trace elements have bulk partition coefficient values that range from ∼.0.1 up to ∼.0.8 (Sr, Hf, Zr, Y and REE). Magnetites incorporate greater amounts of Nb and Ta than the titanaugites, and any significant fractionation of magnetite would have affected the bulk distribution of Nb and Ta. The LREE have lower Kd values than other REE, with the HREE having Kd values close to unity. Consequently, with the separation of titanaugite an overall enrichment of REE in the residual liquid with an increase in the La/Yb ratio is produced.

Trace element partitioning between wollastonite and silicate-carbonate melt

2000 ◽  
Vol 64 (4) ◽  
pp. 651-661 ◽  
Author(s):  
K. M. Law ◽  
J. D. Blundy ◽  
B. J. Wood ◽  
K. V. Ragnarsdottir
Keyword(s):  
Young’S Modulus ◽  
Partition Coefficients ◽  
Young's Modulus ◽  
Divalent Cations ◽  
Experimental Conditions ◽  
Ionic Radii ◽  
Element Partitioning ◽  
Carbonate Complexation ◽  
Silicate Carbonate ◽  
Carbonate Melt

AbstractWe have performed an experimental study of the influence of varying size and charge on cation partitioning between wollastonite and silicate-carbonate melt in the system CaCO3-SiO2. The experimental conditions (3 GPa, 1420°C) lie close to the wollastonite II tc/I tc phase boundary. Results for 1+, 2+, 3+ and 4+ partitioning show parabolic dependence of partition coefficients on ionic radius, which can be fitted to the elastic strain model of Blundy and Wood (1994), wherein partitioning is described using three parameters: site radius (r0), site elasticity (apparent Young's Modulus) and the ‘strain-free’ partition coefficient (D0) for an element with radius r0. The apparent Young's Modulus of the Ca site in wollastonite, obtained from modelling the 2+ partitioning data, is 99±3 GPa, similar to the bulk-crystal value for the polymorph wollastonite I tc. r0 decreases with increasing charge on the substituent cation, while D0 also shows an approximately parabolic dependence on charge, with a maximum for 2+ cations. Partition coefficients for divalent cations Zn, Co, Fe, Cd, Mn and Pb are lower than would be predicted from their ionic radii alone, indicating a preference for the melt. This may be a consequence either of cation-carbonate complexation in the melt, or of the more distorted nature of cation co-ordination environments in melts.

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