Extent Of Solid Solution Research Articles

Mineralogy of Pt-Pd sulfides: The Redefinition of Braggite and Vysotskite (with Comments on the Extent of Solid Solution in the PtS–PdS Binary)

AbstractA re-evaluation of data relating to the crystal structures, phase equilibria, and ideal chemical formulae of the key minerals belonging to the PtS–PdS binary, namely vysotskite, braggite, and cooperite, has led to redefinitions of the ideal chemical formulae for vysotskite and braggite. Results show that vysotskite and braggite are isostructural and crystallize in the space group P42/m. Their crystal structures contain three Me sites and a single S site, giving rise to the general crystal-chemical formula Me(1)2Me(2)2Me(3)4S8. Ordering of Pt and Pd leads to the revised ideal formula of Pd2Pd2Pd4S8 (Z = 1) for vysotskite, which can be simplified to PdS (Z = 8), and a revised ideal formula of Pd2Pt2Pt4S8 (Z = 1) for braggite, which can be simplified to PdPt3S4 (Z = 2). Cooperite, ideally PtS (Z = 8), crystallizes in a related, but different, space group, P42/mmc. Its crystal structure contains a single Me and S site. Both Pt and Pd are disordered over the Me site but with Pt > Pd . Oversimplification of the ideal chemical formulae for all these minerals and failure to consider crystal-structure implications has led to confusion in the literature.Consideration of experimental data combined with that for minerals from world-wide occurrences suggests complete solid solution between vysotskite and braggite, but of a more limited degree between cooperite and braggite, consistent with what would be expected when their respective crystal structures are considered. The maximum Pt possible in braggite should correspond to (Pd0.51Pt0.49)Σ1Pt3S4 (or Pd0.51Pt3.49S4); Pt:Pd = 0.87, which requires Pd 6.29, Pt 78.86, S 14.85, total 100.00 wt.%) and the maximum Pd content, to Pd(Pt0.505Pd0.495)Σ1(Pt1.505Pd0.495)Σ2S4 (or Pd1.99Pt2.01S4); Pt:Pd = 0.50, which requires Pd 28.93, Pt 53.56, S 17.52, total 100.00 wt.%). In light of the complete solid solution between vysotskite and braggite, the 50% rule should be applied to compositions between them. Thus, within the PtS–PdS binary, it is recommended that (1) vysotskite be used for those minerals having compositions ranging from 100 to 56.5 mol.% PdS; (2) braggite, for those having compositions that range from 56.5 to 13 mol.% PdS; and (3) cooperite, for those having <13 mol.%.

Preparation of fine-grained Mo W solid solution alloys with excellent performances

Molybdenum‑tungsten (MoW) alloy composed of molybdenum (Mo) and tungsten (W), is a popular high-temperature material. In this paper, a new method for preparing MoW solid solution alloy has been proposed. To resolve the problem of low extent of solid solution and large grain size, ultrafine MoW composite powder and Mo-W-Al2O3 composite powder were synthesized by spray drying combined with carbothermic pre-reduction and deep reduction by hydrogen. The results show that the method can effectively promote the formation of MoW solid solution, and the particle sizes of the four composite powders (Mo-30 W, Mo-50 W, Mo-30 W-0.5Al2O3, Mo-50 W-0.5Al2O3) were 50–200 nm. After sintering at 1600 °C, all alloys can achieve a high relative density (97%-98%) while retaining a small grain size and good comprehensive properties. Meanwhile, the effect of Al2O3 doping on the sintering performance of MoW alloys was also investigated in detail. The results showed that doping of 0.5 wt%Al2O3 reduced the grain size of MoW alloy from 5 μm to 3 μm. In addition, the hardness of Mo-30 W alloy and Mo-50 W alloy were increased to 471 HV and 534 HV, while the bending strength was increased to 612 MPa and 647 MPa, respectively.

Unnamed Pt(Cu0.67Sn0.33) from the Bolshoy Khailyk River, Western Sayans, Russia, and a Review of Related Compounds and Solid Solutions

We describe a potentially new species of a platinum cupride–stannide mineral (PCSM) of composition Pt(Cu0.67Sn0.33). It occurs in a placer deposit in the River Bolshoy Khailyk, southern Krasnoyarskiy kray, Russia. A synthetic equivalent of PCSM was obtained and characterized. The PCSM occurs as anhedral or subhedral grains up to 15 μm × 30 μm in association with various platinum-group minerals, Rh–Co-rich pentlandite and magnetite, all hosted by a placer grain of Cu–Au–Pt alloy. Synchrotron micro-Laue diffraction studies indicate that the PCSM mineral is tetragonal and belongs to the inferred space-group P4/mmm (#123). Its unit-cell parameters are a = 2.838 (3) Å, c = 3.650 (4) Å, and V = 29.40 (10) Å3, and Z = 1. The c:a ratio calculated from the unit-cell parameters is 1.286. These characteristics are in good agreement with those obtained for specimens of synthetic Pt(Cu0.67Sn0.33). A review on related minerals and unnamed phases is provided to outline compositional variations and extents of solid solutions in the relevant systems PtNi–PtFe–PtCu, PdCu–PdHg–PdAu, PdHg–PtHg, and AuCu–PtCu. The PCSM-bearing mineralization appears to be related genetically with an ophiolitic source-rock of the Aktovrakskiy complex of the western Sayans. The unnamed phase likely crystallized from microvolumes of a highly fractionated melt rich in Cu and Sn.

High Throughput Discovery and Design of Strong Multicomponent Metallic Solid Solutions

High Entropy Alloys (HEAs) are new classes of structural metallic materials that show remarkable property combinations. Yet, often times interesting compositions are still found by trial and error. Here we show an “Effective Atomic Radii for Strength” (EARS) methodology, together with different semi-empirical and first-principle models, can be used to predict the extent of solid solution strengthening to discover and design new HEAs with unprecedented properties. We have designed a Cr45Ni27.5Co27.5 alloy with a yield strength over 50% greater with equivalent ductility than the strongest HEA (Cr33.3Ni33.3Co33.3) from the CrMnFeNiCo family reported to date. We show that values determined by the EARS methodology are more physically representative of multicomponent concentrated solid solutions. Our methodology permits high throughput, property-driven discovery and design of HEAs, enabling the development of future high-performance advanced materials for extreme environments.

Hardness characteristic and shear band formation in metastable β-titanium alloys

Present work describes the formation of shear bands during Vickers indentation with indentation loads in the range of 0.1 to 20kg in four metastable β titanium alloys in β water quench condition. Extent of solid solution has marked influence on the evolution of shear bands. All the four alloys exhibit both the primary and secondary shear bands. The spacing between shear bands increases with increase in distance from the indenter edge. Crystal orientation mapping has been used to measure misorientations at different locations within the matrix, shear bands and at the interface between matrix and shear band.

Paragenesis and chemical characteristics of the celsian−hyalophane−K-feldspar series and associated Ba-Cr micas in barite-bearing strata of the Mesoarchaean Ghattihosahalli Belt, Western Dharwar Craton, South India

The upper greenschist - lower amphibolite facies, argillaceous to chemical-exhalative metasedimentary sequence of the Mesoarchaean Ghattihosahalli Schist Belt (GHSB), southern India, has been examined with a special focus on the paragenesis and solid solution characteristics of barian feldspars and associated dioctahedral Ba-Cr-bearing micas. Barian feldspars occur as untwinned porphyroblasts in a recrystallized finely banded matrix of barite, quartz and minor white mica. Idioblastic celsian (Cls98-76Or2-20Ab1-8) and hyalophane (Cls55-39Or35-51Ab10) predate the greenschist-facies foliation, whereas xenoblastic hyalophane (Cls44-35Or45-59Ab8–17) and mantles on celsian (Cls45-35Or42-60Ab13-5) as well as xenoblastic barian K-feldspar (Cls6Or90Ab2) postdate the last fabric-defining event. The preservation of extremely complex zoning patterns down to the micron-scale shows that diffusional homogenization did not operate at fluid-present low to medium-grade conditions (350–550 °C, 3–5 kb). Microstructures indicate that at these conditions barian feldspars deform exclusively by brittle fracturing and do not undergo recrystallization. Barian feldspar compositions confirm the positive correlation of Na-content with temperature and the existence of a narrow asymmetric compositional gap (Cls90-85↔Cls55, ~350 °C) which probably closes at lower amphibolite facies conditions (Xc ~Cls75; Tc ~550 °C). White micas are solid solutions of the end-members muscovite, ganterite (Ba0.5 K0.5)Al2(Al1.5Si2.5)O10(OH)2, paragonite, celadonite with a significant substitution of [VI]Al by Cr. Zoning is a common feature with cores being enriched in Ba. The data document extensive Ba substitution for K from muscovite to ganterite, exclusively controlled by the coupled substitution [XII]K + [IV]Si ↔ [XII]Ba + [IV]Al and strongly dependent on bulk composition. The extent of solid solution from (Ms+Gnt) towards paragonite and celadonite end-members is controlled by the miscibility gap in the (Ms+Gnt)–Pg–Cel pseudoternary, with the Pg-substitution depending on temperature and the Cel-substitution on pressure. [IV]Si values between 3.1 and 3.3 in Ba-poor micas indicate minimum pressures of chemical equilibration in the order of 3–5 kbar, while the most sodian compositions of low-celadonite micas provide an upper temperature estimate of ~550 °C, consistent with P-T estimates for assemblages of metapelites (500–550 °C, 4–5 kb).

Electrochemical Performance of Ni1-xCox-GDC Cermet Anodes for SOFCs

Electrochemical performance of Ni1-xCox-GDC (Gd0.1Ce0.9O1.95) cermet was studied for the use as a novel anode for solid oxide fuel cells (SOFCs). Ni1-xCoxO (x=0.25, 0.5, 0.75) was prepared from NiO and Co3O4 compounds via a solid state calcination at 1000°C for 10h in air. A progressive increase in lattice parameters of the Ni1-xCoxO as x was increased suggested the extent of solid solution between NiO and Co3O4. The trace of free Co3O4 was found only in the Ni0.25Co0.75O calcined powder indicating incomplete dissolution between NiO and Co3O4 at this condition. After reduction at 800°C for 2h in H2, the interfacial polarization resistance and current-voltage (I-V) of the Ni1-xCox- GDC//YSZ//LSM-YSZ cells were measured at the temperatures between 650 and 800°C. Grain growth and coarsening of the Ni1-xCox-GDC cermet was generally observed when the amount of Co atomic fraction was increased especially at x = 0.75. The Ni0.75Co0.25-GDC anode exhibited the better uniform microstructure, as compared to other composite anodes, resulting in enhanced electrochemical performance of the cells. When the grain coarsening occurred, suppression of the overall electrochemical performance of the cells was obtained.

Compositional limits and analogs of monoclinic triple-chain silicates

Growing recognition of triple-chain silicates in nature has prompted experimental research into the conditions under which they can form and the extent of solid solution that is feasible for some key chemical substitutions. Experiments were done primarily in the range of 0.1–0.5 GPa and 200–850 °C for durations of 18–1,034 h. A wide range of bulk compositions were explored in this study that can be classified broadly into two groups: those that are Na free and involve various possible chemical substitutions into jimthompsonite (Mg10Si12O32(OH)4), and those that are Na bearing and involve chemical substitutions into the ideal end-member Na4Mg8Si12O32(OH)4. Numerous attempts to synthesize jimthompsonite or clinojimthompsonite were unsuccessful despite the type of starting material used (reagent oxides, magnesite + SiO2, talc + enstatite, or anthophyllite). Similarly, the chemical substitutions of F− for OH−, Mn2+, Ca2+, or Fe2+ for Mg2+, and 2Li+ for Mg2+ and a vacancy were unsuccessful at nucleating triple-chain silicates. Conversely, nearly pure yields of monoclinic triple-chain silicate could be made at temperatures of 440–630 °C and 0.2 GPa from the composition Na4Mg8Si12O32(OH)4, as found in previous studies, though its composition is most likely depleted in Na as evidenced by electron microprobe and FTIR analysis. Pure yields of triple-chain silicate were also obtained for the F-analog composition Na4Mg8Si12O32F4 at 550–750 °C and 0.2–0.5 GPa if a flux consisting of Na-halide salt and water in a 2:1 ratio by weight was used. In addition, limited chemical substitution could be documented for the substitutions of 2 Na+ for Na+ + H+ and of Mg2+ + vacancy for 2Na+. For the former, the Na content appears to be limited to 2.5 cations giving the ideal composition of Na2.5Mg8Si12O30.5(OH)5.5, while for the latter substitution the Na content may go as low as 1.1 cations giving the composition Na1.1Mg9.4Si12O31.9(OH)4.1 based on a fixed number of Si cations. Further investigation involving Mg for Na cation exchange may provide a pathway for the synthesis of Na-free clinojimthompsonite. Fairly extensive solid solution was also observed for triple-chain silicates made along the compositional join Na4Mg8Si12O32(OH)4–Ca2Mg8Si12O32(OH)4 where the limit of Ca substitution at 450 °C and 0.2 GPa corresponds to Na0.7Ca1.8Mg7.8Si12O31.9(OH)4.1 (with the OH content adjusted to achieve charge balance). Aside from the Na content, this composition is similar to that observed as wide-chain lamellae in host actinolite. The relative ease with which Na-rich triple chains can be made experimentally suggests that these phases might exist in nature; this study provides additional insights into the range of compositions and formation conditions at which they might occur.

Solid solution behaviour of CaSiO3 and MgSiO3 perovskites

Using density functional simulations within the generalized gradient approximation and projector-augmented wave method together with thermodynamic modelling, the reciprocal solubilities of MgSiO3 and CaSiO3 perovskites were calculated for pressures and temperatures of the Earth’s lower mantle from 25 to 100 GPa and 0 to 6,000 K, respectively. The solubility of Ca in MgSiO3 at conditions along a mantle adiabat is found to be less than 0.02 atoms per formula unit. The solubility of Mg in CaSiO3 is even lower, and most important, the extent of solid solution decreases with pressure. To dissolve CaSiO3 perovskite completely in MgSiO3 perovskite, a solubility of 7.8 or 2.3 mol% would be necessary for a fertile pyrolytic or depleted harzburgitic mantle, respectively. Thus, for any reasonable geotherm, two separate perovskites will be present in fertile mantle, suggesting that Ca-perovskite will be residual to low degree melting throughout the entire mantle. At the solidus, CaSiO3 perovskite might completely dissolve in MgSiO3 perovskite only in a depleted mantle with <1.25 wt% CaO. These implications may be modified if Ca solubility in MgSiO3 is increased by other major mantle constituents such as Fe and Al.

Grain growth kinetics of dolomite, magnesite and calcite: a comparative study

The rates of grain growth of stoichiometric dolomite [CaMg(CO3)2] and magnesite (MgCO3) have been measured at temperatures T of 700–800°C at a confining pressure Pc of 300 MPa, and compared with growth rates of calcite (CaCO3). Dry, fine-grained aggregates of the three carbonates were synthesized from high purity powders by hot isostatic pressing (HIP); initial mean grain sizes of HIP-synthesized carbonates were 1.4, 1.1, and 17 μm, respectively, for CaMg(CO3)2, MgCO3, and CaCO3, with porosities of 2, 28, and 0.04% by volume. Grain sizes of all carbonates coarsened during subsequent isostatic annealing, with mean values reaching 3.9, 5.1, and 27 μm for CaMg(CO3)2, MgCO3, and CaCO3, respectively, in 1 week. Grain growth of dolomite is much slower than the growth rates of magnesite or calcite; assuming normal grain growth and n = 3 for all three carbonates, the rate constant K for dolomite (≃5 × 10−5 μm3/s) at T = 800°C is less than that for magnesite by a factor of ~30 and less than that for calcite by three orders of magnitude. Variations in carbonate grain growth may be affected by differences in cation composition and densities of pores at grain boundaries that decrease grain boundary mobility. However, rates of coarsening correlate best with the extent of solid solution; K is the largest for calcite with extensive Mg substitution for Ca, while K is the smallest for dolomite with negligible solid solution. Secondary phases may nucleate at advancing dolomite grain boundaries, with implications for deformation processes, rheology, and reaction kinetics of carbonates.

Phase equilibrium in the Pb2SnSb2S6-SnS system

The Pb2SnSb2S6-SnS system was studied over a wide range of concentrations using a set of physicochemical methods (powder X-ray diffraction, DTA, microstructure examination, and microhardness measurement). A phase diagram for the title quasi-binary join was constructed for the first time. The phase diagram is of the eutectic type; the eutectic coordinates are 25 mol % SnS and 775 K. The extents of solid solutions based on the terminal components were determined to be 10 mol % SnS and 5 mol % Pb2SnSb2S6. Alloys having compositions in the SnS-based solid solution region are semiconductors.

Simulation of thermodynamic mixing properties of actinide-containing zircon solid solutions

Solid solutions among zircon (ZrSiO4, I41/amd) and zircon-structured orthosilicates ASiO4 (A = Hf, Th, U, Pu, or Ce) are important to a wide variety of applications: nuclear materials, geochronology, and even electronic materials. The thermodynamic mixing properties of the following seven binary solid solutions were simulated using density functional theory followed by Monte Carlo modeling and thermodynamic integration: (Zr,Hf)SiO4, (Zr,Th)SiO4, (Zr,U)SiO4, (Zr,Pu)SiO4, (Zr,Ce)SiO4, (Hf,Pu) SiO4, and (Th,U)SiO4. ZrSiO4 and HfSiO4 were found to form a nearly ideal solid solution, but the miscibility of the other solid solutions was limited to no more than 12 mol% of the substituting cation. The binaries were ranked by extent of miscibility: (Zr,Hf)SiO4 > (Th,U)SiO4 > (Zr,Pu)SiO4 > (Zr,Ce) SiO4 > (Hf,Pu)SiO4 > (Zr,U)SiO4 > (Zr,Th)SiO4. The extent of solid solution has been estimated for each binary. The end-members PuSiO4, CeSiO4, and USiO4 were determined to be unstable relative to a mixture of SiO2(quartz) and crystalline PuO2, CeO2(cerianite), or UO2(uraninite). Isostructural thorite (ThSiO4) is calculated to be marginally stable, but its monoclinic polymorph, huttonite, which has the structure of monazite, is marginally unstable relative to SiO2(quartz) and ThO2(thorianite) at 0 K. If thermodynamic equilibrium could be reached at low temperatures, exsolution textures would appear in most zircon solid solutions perpendicular to [001], but perpendicular to a linear combination of [100] and [010] in (Hf,Pu)SiO4.

A measure of the solid-solution extent useful for crystallisation resolution studies

The ratio of partition coefficients of molecular components between crystal and liquor phases gives a measure of the solid-solution extent, termed D. This measure is considered useful to compare the results of resolution experiments and to make predictions of the crystal composition obtained under different starting compositions and crystal yields. The calculations show that a small extent of solid solution (e.g., 0.1%) can have a noticeable effect, and that the maximum efficiency of a resolution in certain cases is determined by the solid-solution extent rather than by the eutectic composition with the opposite isomer.

Study on Microstructure of Alumina Based Rare Earth Ceramic Composite

Analysis techniques such as SEM, TEM and EDAX were used to investigate the microstructure of rare earth reinforced Al 2O 3/(W, Ti)C ceramic composite. Chemical and physical compatibility of the composite was analyzed and interfacial microstructure was studied in detail. It is found that both Al 2O 3 and (W, Ti)C phases are interlaced with each other to form the skeleton structure in the composite. A small amount of pores and glass phases are observed inside the material which will inevitably influence the physical and mechanical property of the composite. Thermal residual stresses resulted from thermal expansion mismatch can then lead to the emergence of dislocations and microcracks. Interfaces and boundaries of different types are found to exist inside the Al 2O 3/(W, Ti)C rare earth ceramic composite, which is concerned with the addition of rare earth element and the extent of solid solution of ceramic phases.

Interaction of argyrodite family compounds with the chalcogenides of II-b elements

Using the results of DTA, X-ray phase analysis and metallography, we constructed phase diagrams of a series of sections of quasi-ternary systems Ag 2X–A IIX–B IVX 2 formed by the compounds of the argyrodite family, Ag 8B IVX 6, and by A IIX compounds (A II = Zn, Cd; B IV = Si, Ge, Sn; X = S, Se). The formation of solid solution ranges of ternary argyrodites is established; the maximum extent of solid solutions is observed at the temperatures of non-variant processes and decreases substantially with temperature decrease. The eutectic interaction is typical of zinc-containing sections. Both peritectic (Ag 8Si(Ge)S 6–CdS, Ag 8SiSe 6–CdSe) and eutectic (Ag 8SnS 6–CdS, Ag 8Ge(Sn)Se 6–CdSe) type of interaction is found among cadmium-containing systems. The possibility of obtaining eutectic crystals by directed crystallization of the melt of eutectic point composition is shown.

Phase Equilibria in the System “MnO”–CaO–MgO–SiO2–Al2O3 with Al2O3/SiO2 Weight Ratio of 0.17 and MgO/CaO Weight Ratio of 0.25 at Mn–Si Alloy Saturation

Liquidus isotherms and phase equilibria have been determined experimentally for a pseudo-ternary section of the form “MnO”-(CaO + MgO)-(SiO +Al O) with a fixed Al O /SiO weight ratio of 0.17 and MgO/CaO weight ratio of 0.25 for temperatures in the range 1 393-1 673 K. The primary phase fields found in the investigated section include manganosite (Mn, Mg, Ca)O; dicalcium silicate α-2(Ca, Mg, Mn)O·SiO; merwinite 3CaO (Mg, Mn)O 2SiO; melilite [2CaO·(MgO, MnO, AlO)·2(SiO· , Al O )]; wollastonite [(Ca, Mg, Mn)O·SiO ]; diopside [(CaO, MgO, MnO, Al O )·SiO ]; tridymite (SiO ); rhodonite [(Mn, Mg, Ca)O·SiO ]; anorthite (CaO·Al O 2SiO ) and tephroite [2(Mn, Mg, Ca)O·SiO ]. The liquidus temperatures and primary phase fields are significantly different to those in the ternary system “MnO”-CaO-SiO , but are close to those previously reported pseudo-ternary section “MnO”-(CaO + MgO)-(SiO +Al O ) for Al O /SiO weight ratio of 0.17 and MgO/CaO weight ratio of 0.17. The partitioning of CaO, MgO and MnO between liquid and solid phases was measured using EPMA, and the extents of solid solutions for a range of bulk compositions and temperatures were characterised.

Experimental study of phase equilibria in the Al-Fe-Zn-O system in air

The phase equilibria in the Al-Fe-Zn-O system in the range 1250 °C to 1695 °C in air have been experimentally studied using equilibration and quenching techniques followed by electron probe X-ray microanalysis. The phase diagram of the binary Al2O3-ZnO system and isothermal sections of the Al2O3-“Fe2O3”-ZnO system at 1250 °C, 1400 °C, and 1550 °C have been constructed and reported for the first time. The extents of solid solutions in the corundum (Al,Fe)2O3, hematite (Fe,Al)2O3, Al2O3*Fe2O3 phase (Al,Fe)2O3, spinel (Al,Fe,Zn)O4, and zincite (Al,Zn,Fe)O primary phase fields have been measured. Corundum, hematite, and Al2O3*Fe2O3 phases dissolve less than 1 mol pct zinc oxide. The limiting compositions of Al2O3*Fe2O3 phase measured in this study at 1400 °C are slightly nonstoichiometric, containing more Al2O3 then previously reported. Spinel forms an extensive solid solution in the Al2O3-“Fe2O3”-ZnO system in air with increasing temperature. Zincite was found to dissolve up to 7 mole pct of aluminum in the presence of iron at 1550 °C in air. A meta-stable Al2O3-rich phase of the approximate composition Al8FeZnO14+x was observed at all of the conditions investigated. Aluminum dissolved in the zincite in the presence of iron appears to suppress the transformation from a round to platelike morphology.

MONOVALENT CATIONS IN STRUCTURES OF THE META-AUTUNITE GROUP

Compounds of the meta-autunite group containing monovalent cations (Li, Na, K, Rb, Cs, Ag, Tl) have been synthesized by diffusion in gels or by hydrothermal methods, and their crystal structures determined. Single-crystal X-ray-diffraction intensity data were collected at room temperature using MoKradiation and a CCD-based area detector. These compounds contain the autunite-type sheet with composition ((UO2)(XO4)) - , X = P or As, which involves the sharing of equatorial vertices of uranyl square bipyramids with tetrahedra. The interlayer region contains cations and H2O groups, and the sheets are linked by hydrogen bonding and through bonds from the interlayer cations to oxygen atoms of the sheets. The structural roles of the interlayer cations in determining the symmetries and hydration states observed are discussed. The smallest monovalent cation, Li, occurs in tetra- hedral coordination between fourfold squares of hydrogen-bonded H2O groups. Despite a wide range in ionic radius, Na, K, Rb, Ag and Tl randomly substitute for H2O groups in the interlayer, in the same fashion as their ammonium and oxonium analogues. The large Cs cation adopts independent crystallographic sites in the interlayer. The size difference between Cs and the other monovalent cations probably prevents their direct substitution, and may limit the extent of solid solution. With the exception of

EXPERIMENTAL STUDY OF PHASE EQUILIBRIA IN THE Fe-Sn-Zn-O SYSTEM IN AIR

The four-component Fe-Sn-Zn-O system was studied experimentally in the range of temperatures from 1100 to 1400 °C in air using high temperature equilibration and quenching techniques followed by electron probe X-ray microanalysis (EPMA). Phase equilibrium relations and the extent of solid solutions among the phases cassiterite (Sn,Zn)O2, hematite (Fe,Sn,Zn)2 O3, spinel (Fe,Sn,Zn)3 O4 and zincite (Zn,Fe,Sn)O are reported. Phase equilibria in the pseudo-binary systems Fe2 O3 -SnO2 and SnO2 -ZnO are reported in air in the temperature ranges from 1100 to 1400 °C and 1200 to 1400 °C, respectively.On a étudié expérimentalement le système Fe-Sn-Zn-O à quatre constituants dans la gamme de températures de 1100 à 1400 °C, dans l’air, en utilisant des techniques d’équilibration à haute température et de trempe suivies par une analyse par microsonde électronique (EPMA). On décrit les relations d’équilibre de phases et le degré de solutions solides entre les phases cassitérite (Sn,Zn)O2, hématite (Fe,Sn,Zn)2 O3, spinelle (Fe,Sn,Zn)3 O4 et zincite (Zn,Fe,Sn)O. On décrit les équilibres de phases des systèmes pseudo-binaires Fe2 O3 -SnO2 et SnO2 -ZnO, dans l’air, dans les gammes de température de 1100 à 1400 °C et de 1200 à 1400 °C, respectivement.

Investigation of Pu Incorporation into Zircon Single Crystal

AbstractIn order to obtain Pu-doped zircon, (Zr,Pu)SiO4, with a maximum Pu content in the form of solid solution, zircon single crystals have been grown using the flux method from starting materials overloaded with Pu. The crystals obtained ranged from 0.2-0.5 to 3.5-4.5 mm in size, are transparent, and characterized by deep pink-brown color. No inclusions of separate Pu phases were observed in the crystals. The distribution of Pu in crystals is zoned and the Pu content varying from approximately 5 to 14 wt.% el. The zircon unit cell parameters calculated from XRD data of bulk powdered sample were: a=6.620(1); c=5.989(2). The results obtained allow us to conclude that the capacity of the zircon structure to incorporate Pu exceeds 10 wt.% el.; however, additional research is required to study the extent of solid solution, (Zr,Pu)SiO4, at higher Pu contents.