Wide Range Of Solid Solutions Research Articles

The Magnetism of Nonstoichiometric Sr2Cr1+xRe1-xO6 (0 < x < 0.5) Double Perovskites.

The effect of nonstoichiometry on the cation distribution, crystal structure, and magnetic properties of a series of Cr-rich Sr2Cr1+xRe1-xO6 samples has been investigated. The double perovskite structure is maintained over a wide solid solution range that extends from x = 0 to approximately x = 0.5. For most of the solid solution range, the Cr-rich octahedral site maintains a nearly constant occupancy, 87% Cr and 13% Re, that is comparable to prior studies of Sr2CrReO6, while Cr steadily replaces Re on the other octahedral site. As x approaches 0.5, long-range Cr/Re ordering drops precipitously. Analysis of X-ray powder diffraction peak shapes reveals antiphase boundaries, associated with Cr/Re ordering, the concentration of which increases steadily with increasing x. Neutron powder diffraction studies confirm antiferromagnetic coupling between antisite Cr3+ ions and Cr3+ ions that occupy the normal sites, leading to site-dependent ferrimagnetic ordering. Density functional theory calculations indicate that chromium maintains a +3 oxidation state across the series, while the oxidation state of rhenium increases with increasing x. Calculations are also used to explore the energies of competing magnetic ground states. Except for the most chromium-rich compositions (x ≈ 0.5), site-dependent ferrimagnetism is retained with only a modest reduction in TC. The saturation magnetization steadily decreases as the chromium content increases due to a combination of Cr/Re antisite disorder and antiphase boundaries.

Nitrogen under Super-Reducing Conditions: Ti Oxynitride Melts in Xenolithic Corundum Aggregates from Mt Carmel (N. Israel)

Titanium oxynitrides (Ti(N,O,C)) are abundant in xenolithic corundum aggregates in pyroclastic ejecta of Cretaceous volcanoes on Mount Carmel, northern Israel. Petrographic observations indicate that most of these nitrides existed as melts, immiscible with coexisting silicate and Fe-Ti-C silicide melts; some nitrides may also have crystallized directly from the silicide melts. The TiN phase shows a wide range of solid solution, taking up 0–10 wt% carbon and 1.7–17 wt% oxygen; these have crystallized in the halite (fcc) structure common to synthetic and natural TiN. Nitrides coexisting with silicide melts have higher C/O than those coexisting with silicate melts. Analyses with no carbon fall along the TiN–TiO join in the Ti–N–O phase space, implying that their Ti is a mixture of Ti3+ and Ti2+, while those with 1–3 at.% C appear to be solid solutions between TiN and Ti0.75O. Analyses with &gt;10 at% C have higher Ti2+/Ti3+, reflecting a decrease in fO2. Oxygen fugacity was 6 to 8 log units below the iron–wüstite buffer, at or below the Ti2O3–TiO buffer. These relationships and coexisting silicide phases indicate temperatures of 1400–1100 °C. Ti oxynitrides are probably locally abundant in the upper mantle, especially in the presence of CH4–H2 fluids derived from the deeper metal-saturated mantle.

Phase equilibria of Al2O3–TiOx system under various oxygen partial pressure: Emphasis on stability of Al2TiO5–Ti3O5 pseudobrookite solid solution

Phase equilibria of Al2O3–TiOx system were experimentally determined in a wide range of T and PO2: 1300 °C ≤T≤ 1600 °C and −16.6≤logPO2≤−8.0 (in atm). X-Ray diffraction and electron probe micro-analysis were employed to obtain equilibrium phases and compositions. Corundum (Al2O3 with limited Ti2O3), rutile (TiO2 with limited Al2O3), and pseudobrookite (Al2TiO5–Ti3O5) solid solutions were found. The liquid oxide phase was not found up to 1650 °C. At each temperature, the cationic ratio of the pseudobrookite solid solution (RTi = nTi/(nAl + Ti)) increased as PO2, thereby forming a wide range of solid solution from Al2TiO5 (RTi = 1/3) to Ti3O5 (RTi = 1.0). The pseudobrookite solid solution was a complete miscible solution at 1600 °C, while it exhibited a small miscibility gap at 1500 °C. Based on the results obtained in the present study, the behavior of Al2TiO5 was discussed in two aspects: (1) changes in physical properties and (2) evolution of Al–Ti complex oxide inclusions in liquid steel.

Experimental investigation and thermodynamic calculation of Ti-Hf-Mn system

The phase relationship of Ti-Hf-Mn system was studied by diffusion triple and equilibrated alloy methods. The isothermal sections at 1373, 1273 and 1173 K for this system were constructed by means of electron probe microanalysis (EPMA) and X-ray diffraction (XRD) for the first time. No ternary phase was found in the system at all these temperatures. Six, seven and seven three-phase equilibria regions have been determined at 1373, 1273 and 1174 K, respectively. In this ternary system, the intermetallic compounds TiMn2, HfMn2 and HfMn exhibit wide solid solution range at those three temperatures. In particular, the solution range of Ti in HfMn phase decreases with the increase of temperature, from 30.5 at% at 1173 K to 26.5 at% at 1373 K. Based on all available experimental data, the Ti-Hf-Mn system was evaluated using the CALPHAD method. The calculation results are in excellent agreement with the experimental data.

Dry Adhesive Friction Process Regularities during Frictional Contact of Heterogeneous “Copper-Aluminum” System Materials

By means of optical and scanning electron microscopy the surface layer structure of aluminum alloy AMg5 samples with introduced copper part after adhesive frictional contact with AISI 420 steel counterbody was studied. It is revealed that under plastic deformation and material fragmentation in the frictional contact zone a complex mixture of different phase layers is formed due to the formation of different flows of aluminum alloy and copper during friction. Mechanical mixing of a material occurs on all length of a friction path with different intensity depending on distance to copper fragment. Both laminar and turbulent flows of material are formed in the surface layer, as well as a wide range of solid solutions, intermetallic phases and mechanical mixtures.

Effects of Filler Metals on Heat-Affected Zone Cracking in IN-939 Superalloy Gas-Tungsten-Arc Welds

Filler metals play an important role in reducing the weld cracking in nickel-based superalloys. In order to improve the welding conditions of IN939 superalloy, a wide range of solid solutions and age-hardenable filler metals were investigated in this study. Five solid solutions (HAYNES 230, IN625, IN617, HASTELLOY X, HAYNES 25) and two precipitation-strengthened alloys (IN718, HAYNES C-263) were used as filler metal to weld IN939 superalloy via gas-tungsten-arc welding. Microstructural studies were performed using optical microscopy and field-emission scanning electron microscopy. The results revealed that IN939 alloy is susceptible to liquation cracking in the heat-affected zone. In addition, the primary γ′ particles had grown into “ogdoadically diced cubes” of about of 2 μm in side length. The microstructure of the weld pool made with various filler metals was observed to be made up of fine spherical γ′ particles with a diameter of about 0.2 μm. The study of mechanical properties and thermodynamic behavior of the weld showed that the filler metals with lower concentrations of (Al + Ti + Nb + Ta + Mo + W) than the base metal can effectively attenuate the PWHT cracking. We found that optimal IN939 alloy weld performance can be achieved using HAYNES C-263 as filler metal, followed by IN617 and then IN625.

Group 14 element based sodium chalcogenide Na4Sn0.67Si0.33S4 as structure template for exploring sodium superionic conductors

Sodium superionic conductors are keys to realize room-temperature and high safety all-solid-state sodium batteries. Sulfide based sodium superionic conductors are promising but most reported examples are based on group 15 elements. To extend the horizon, we demonstrate a development route from group 14 elements based sodium chalcogenide. Na4Sn0.67Si0.33S4 shows a distinctly new structure with space group I41/acd and 3D diffusion pathway by silicon doping in Na4SnS4, which exhibits 2 orders of magnitude conductivity improvement than that of the mother compound Na4SnS4. And the Na4Sn0.67Si0.33S4 can be taken as a high tolerance structural template for chemical manipulation. Based on the structural template, aliovalent substitution of P5+ for M4+ leads to a wide range of solid solutions of Na4-x[Sn0.67Si0.33]1-xPxS4 (0 ≤ x ≤ 0.4) with enhanced sodium conductivity. The highest ionic conductivity reaches 1.6 × 10−3 S cm−1 with x = 0.25. Change of vacancy population and weak Na-S interaction induced from P doping are main reasons for the improvement of ionic conductivity. In addition, excellent air stability is demonstrated. This work expands the exploration opportunities and provides further understanding of structure-property relationship for sodium superionic conductors.

Synthesis and characterisation of the hollandite solid solution Ba1.2-xCsxFe2.4-xTi5.6+xO16 for partitioning and conditioning of radiocaesium

The geological disposal of high level radioactive waste requires careful budgeting of the heat load produced by radiogenic decay. Removal of high-heat generating radionuclides, such as 137Cs, reduces the heat load in the repository allowing the remaining high level waste to be packed closer together therefore reducing demand for repository space and the cost of the disposal of the remaining wastes. Hollandites have been proposed as a possible host matrix for the long-term disposal of Cs separated from HLW raffinate. The incorporation of Cs into the hollandite phase is aided by substitution of cations on the B-site of the hollandite structure, including iron. A range of Cs containing iron hollandites were synthesised via an alkoxide-nitrate route and the structural environment of Fe in the resultant material characterised by Mössbauer and X-ray Absorption Near Edge Spectroscopy. The results of spectroscopic analysis found that Fe was present as octahedrally co-ordinated Fe (III) in all cases and acts as an effective charge compensator over a wide solid solution range.

Structural aspects of the formation of solid solutions in the NaF-KF-AlF3 system

The formation of solid solutions in the ternary system NaF-KF-AlF3 has been studied by X-ray diffraction and thermal analysis. Chiolite has been shown to form solid solutions with the composition (Na(5−x)Kx)Al3F14, in the limited range of 0<x<0.4. The lattice parameters change in the intervals for (a) 7.010 (3) −7.050 (3) Å, for (c) 10.365 (10) −10.400 (10)Å. According to the investigation of the crystal structure, potassium cations substitute sodium only in the 2-fold position in the amount of ~40%. The solid solutions are stable in the range from room to melting point temperature. A wide range of solid solutions based on β-cryolite (Na3AlF6) and elpasolite (K2NaAlF6) above 540°C has been studied in detail. It is only the 8-fold cationic position in the β-cryolite structure which appears to have contributed into the substitution in the full range of solid solutions. The solid solution decays into a mixture of α-Na3AlF6 and K2NaAlF6 upon calcination below 540°C., followed by further cooling without changing the α-Na3AlF6 composition. Elpasolitе initially containing an excess of sodium ions, has yielded cryolite and stoichiometric K2NaAlF6 below 340°C. The phase K2NaAl3F12 present in two polymorphic forms, has not formed a wide range of solid solutions; however, a slight excess of potassium ions has improved the stability of the high-temperature form.

Potassium-conducting solid electrolytes in the K3 − 2x Cd x PO4 system

New potassium-conducting solid electrolytes of the K3 − 2xCdxPO4 system are synthesized and studied. A wide range of solid solutions reaching x ≈ 0.35 with the structure of high-temperature modification of potassium orthophosphate forms in the system. An addition of cadmium ions leads to an abrupt increase in the K3PO4 conductivity due to the formation of potassium vacancies. The highest conductivity is approximately 10−2 S cm−1 at 300°C and above 10−1 S cm−1 at 700°C.

SpinelViz: An interactive 3D application for visualizing spinel group minerals

SpinelViz is an application for the visualization of the spinel group minerals in three dimensions. SpinelViz uses the spinel prism to display mineral composition datasets from different tectonic settings. The application projects data onto 2D and 3D plots. Such projections are used to classify spinels based on geochemical data. The spinel mineral group exhibits a wide range of solid solutions and has been the subject of many thermodynamic studies. Spinels, particularly chromites from mafic–ultramafic igneous rocks are used to discriminate among various tectonic settings. Their existence in ultramafic rocks and their resistance to alteration make them excellent tectonic tracers and a very important tool in search for economic deposits of the platinum group elements (PGE) and Ni-Cu-PGE. SpinelViz provides a set of functionalities that helps users to manipulate their datasets for both 2D and 3D visualization and 2D projections.

인도네시아 까시한지역 스카른광체의 광상학적 특성

인도네시아 까시한 지역 함 동-아연 스카른광체는 올리고신 후기 퇴적암류 중 석회암층을 따라 발달한다. 스카른광체의 괴상스카른대는 초기에서 후기로 단사휘석-석류석대, 석류석대, 석류석-녹염석대, 녹염석대 스카른으로 구분된다. 초기 괴상 스카른대에서 산출하는 단사휘석은 투휘석-헤덴버가이트 고용체로서, 초기 투휘석 단성분에 가까운 조성으로부터 후기 salitic 단사휘석으로의 조성변화가 확인된다. 이러한 단사휘석의 조성변화는 일반적인 스카른 광체에서의 수반 금속성분 (Cu 및 Zn광화작용)과 단사휘석 조성 상관관계와 잘 일치한다. 석류석의 경우 그로슐라-안드라다이트 고용체로서 매우 넓은 조성변화를 보여주며, 후기 석류석의 경우 Fe함량의 증가 경향성이 인지된다. 녹염석의 경우 클리노조이사이트-피스타사이트 고용체(65.8-76.2 mol. % 클리노조이사이트)로 확인된다. 상평형관계로 확인된 까시한 지역 함 동-아연 스카른광체는 약 0.5 kb의 환경에서 초기 약 <TEX>$450^{\circ}C$</TEX> (단사휘석-석류석 및 석류석 스카른, <TEX>${\approx}450-370^{\circ}C$</TEX>) 에서 시작되어 후기 <TEX>$300^{\circ}C$</TEX> (석류석-녹염석 및 녹염석 스카른, <TEX>${\approx}370-300^{\circ}C$</TEX>) 에 걸쳐 진행되었다. Copper-zinc-bearing skarns of the Kasihan area developed at limestone layers in the sedimentary facies of the Late Oligocene Arjosari Formation. The skarns consist mainly of fine-grained, massive clinopyroxene-garnet, garnet, garnet-epidote, and epidote skarns. Most copper and zinc(-lead) ore mineralization occur in the clinopyroxene-garnet and garnetepidote skarn, respectively. Clinopyroxene occurs as a continuous solid solution of diopside and hedenbergite (from nearly pure diopside up to <TEX>${\approx}34$</TEX> mole percent hedenbergite), with a maximum 28.2 mole percent johannsenite component. The early and late pyroxenes of Kasihan skarns are diopsidic and salitic, respectively. They fall in the fields typical Cu- and Zn-dominated skarns, respectively. Garnet displays a relatively wide range of solid solution between grossular and andradite with up to <TEX>${\approx}2.0$</TEX> weight percent MnO. Garnet in early pyroxene-garnet skarn ranges from 49.1 to 91.5 mole percent grossular (mainly <TEX>${\geq}78$</TEX> mole % grossular). Garnets in late garnet and garnet-epidote skarns range from 2.8 to 91.4 mole percent grossular (mainly <TEX>${\geq}70$</TEX> mole % for garnet skarn). Epidote compositions indicate solid solutions of clinozoisite and pistacite varying from 65.8 to 76.2 mole percent clinozoisite. Phase equilibria indicate that skarn evolution was the result of interaction of water-rich fluids (<TEX>$X_{CO_2}{\leq}0.1$</TEX>) with original lithologies at <TEX>${\approx}0.5$</TEX> kb with declining temperature (early clinopyroxene-garnet and garnet skarn, <TEX>${\approx}450$</TEX> to <TEX>$370^{\circ}C$</TEX>; late garnet-epidote and epidote skarn, <TEX>${\approx}370$</TEX> to <TEX>$300^{\circ}C$</TEX>).

Phase relation in the BaO–ZrO 2–YO 1.5 system: Presence of separate BaZrO 3 phases and complexity in phase formation

In order to estimate the phase stability and homogeneous range of BaZrO 3, which is expected as a candidate electrolyte material for intermediate temperature solid oxide fuel cell, the phase relation in the BaO–ZrO 2–YO 1.5 systems has been examined at a typical processing temperature of 1600 °C. The stable existence of two cubic phases of BaZrO 3, termed as BZ(I) and BZ(II), with different dopant concentration is observed above 1400 °C in the present study. The latter is of long-range ordered supercell with a wide range of solid solution between Ba 3Zr 2YO 8.5 and Ba 9Zr 4Y 8O 29. Also observed is the presence of liquid phase at higher BaO concentration region above the ternary eutectic temperature that is estimated to be around 1300 °C, giving enormous effects to sintering process when Y 3+ is overdoped beyond the solubility limit. From the present results, the pseudo-ternary phase diagram of BaO–ZrO 2–YO 1.5 of the isothermal section at 1600 °C is proposed.

ChemInform Abstract: New Li+ Ion Conductors, Li4-2xTi1-xSxO4, Based on the Li4TiO4 Structure.

In the system Li4TiO4–Li2SO4, a wide range of solid solutions, Li4 – 2xSxTi1 –xO4(0 < x < 0.2) with Li4TiO4 structure is formed. The ionic conductivity increases with x and exhibits a maximum (bulk) value of 8.30 × 10–6 S cm–1at 27 °C with an activation energy of 0.51 eV for x= 0.2. The enhancement in conductivity is associated with an increase in concentration of lithium-ion vacancies, created via the mechanism 2Li++ Ti4+⇌ S6+, but is attributable specifically to a decrease in activation energy for conduction. This is the first report of high Li+-ion conductivity in the Li4TiO4structural family.

Synthesis of anatase nanoparticles with extremely wide solid solution range and ScTiNbO 6 with α-PbO 2 structure

Anatase-type nanoparticles Sc X Ti 1−2 X Nb X O 2 with wide solid solution range ( X=0–0.35) were hydrothermally formed at 180 °C for 5 h. The lattice parameters a 0 and c 0, and the optical band gap of anatase gradually and linearly increased with the increase of the content of niobium and scandium from X=0 to 0.35. Their photocatalytic activity and adsorptivity by the measurement of the concentration of methylene blue (MB) that remained in the solution in the dark or under UV-light irradiation were evaluated. The anatase phase existed stably up to 900 °C for the samples with X=0.25–0.30 and 750 °C for that with X=0.35 during heat treatment in air. The phase with α-PbO 2 structure and the rutile phases coexisted in the samples with X=0.25–0.30 after heated at temperatures above 900–950 °C. The α-PbO 2 structure having composition ScTiNbO 6 with possibly some cation order similar to that seen in wolframite existed as almost completely single phase after heat treatment at temperatures 900–1500 °C through phase transformation from anatase-type ScTiNbO 6.

Mechanical properties of ceramic-polymer nanocomposites

Nano crystalline powders of Barium Sodium Niobate (BNN) with the composition Ba3-2x Na4+x R Nb10 O30 with (R stands for rare earth = 0, x = 0) have been prepared by conventional ceramic technique. Barium Sodium Niobate can form a wide range of solid solutions, incorporating rare earth and alkali, alkaline earth elements with different composi- tions. The powder belonged to tungsten bronze type structure with tetragonal symmetry and lattice constants a = b = 1.2421 nm and c = 0.3903 nm. XRD (X-ray Diffraction) SEM (Scanning Electron Microscope) and AFM (Atomic Force Microscope) studies revealed that the particle size is in the nanometer range. Composites are prepared by mixing powders of BNN with polystyrene at different volume fractions of the BNN. Melt mixing technique is carried out in a Brabender Plasticoder at a rotor speed of 60 rpm (rotations per minute) for composite preparation. Mechanical properties such as stress-strain behavior, Young's modulus, tensile strength, strain at break etc. are evaluated. Addition of filler enhances the mechanical properties of the polymer such as Young's modulus and tensile strength. The composites showed the trend of perfect adhesion between the filler and the polymer. The filler particles are distributed relatively uniform fash- ion in all composites and the particles are almost spherical in shape with irregular boundaries. To explore more carefully the degree of interfacial adhesion between the two phases, the results are analyzed by using models featuring adhesion param- eter. The experimental results are compared with theoretical predictions.

異常に広い固溶域を持つ(Ba1-xCax)(Sc1/2Nb1/2)O3系ペロブスカイトマイクロ波誘電体の奇妙な挙動

異常に広い固溶域を持つ(Ba1-xCax)(Sc1/2Nb1/2)O3系ペロブスカイトマイクロ波誘電体の奇妙な挙動

Preparation and properties of Ba xSr 1− xCo yFe 1− yO 3− δ cathode material for intermediate temperature solid oxide fuel cells

Ba x Sr 1− x Co y Fe 1− y O 3− δ (BSCF) materials with perovskite structure were synthesized via solid-state reaction. Their structural characteristics, electrical-conduction behavior and cathode performance were investigated. Compared to A-site elements, B-site elements show a wide solid-solution range in BSCF. The electrical-conduction behavior of BSCF obeys the small polaron-hopping mechanism. An increase of Ba or Co content in the BSCF samples results in a decrease of electrical conductivity, which is mainly attributable to the preferential existence of B 3+ rather than B 4+ in Ba- or Co-rich samples. At the same time, this leads to increases in the lattice parameter a and the number of oxygen vacancies. BSCF samples with high Ba content show a high structural stability (high oxygen-loss temperature). Ba 0.6Sr 0.4Co 0.8Fe 0.2O 3− δ and Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3− δ materials present good thermal-cycling stability of the electrical conductivity. Compared with Ba 0.5Sr 0.5Co 0.8Fe 0.2O 3− δ , Ba 0.6Sr 0.4Co 0.8Fe 0.2O 3− δ exhibits a better cathode performance in a Ce 0.8Gd 0.2O 2− δ (GDC)-supported half cell. The cell performance can be improved by introducing a certain amount of GDC electrolyte into the BSCF cathode material.

Microstructure and Compression Behavior of Ti3Al Based Ti-Al-V Ternary Alloys

AbstractThe ordered alloy phase of Ti3Al shows a rather wide solid solution range in aluminum and also in vanadium. Several Ti-Al-V ternary alloys have been prepared to investigate the alloy composition effect upon microstructure, crystallography, and mechanical characteristics. The materials containing 75, 70, and 65 at.% titanium, and 0 or 5 at.% vanadium were prepared by arc melting. Metallographic observation has revealed that the binary Ti-Al alloys contained somewhat coarse grains with about 100 μm grain diameter. In contrast to this, ternary alloys containing 5 at.% vanadium showed smaller grained microstructures with grain diameters around 15 μm. The grain size could not be adjusted to a unified value in the present study. X-ray diffraction study and microanalysis showed that the alloys contained single phase α2. Not every possible diffraction peak of the D019 ordered structure has been observed in the XRD patterns. The lattice parameters, a and c, were observed to decrease as the aluminum content increased and also when vanadium was added. Compression tests have been performed at various temperature ranging from an ambient temperature up to 1300K on rectangular parallelepiped specimens with 2mm×2mm×3mm dimensions. Alloys containing more aluminum showed higher strength, and vanadium addition enhanced the strength of the alloys. In some alloys deformability and strength are both enhanced by vanadium addition in some alloys. Temperature dependence of strength showed a little variation upon chemical compositions.

High-temperature phase relations and topological constraints in the quaternary system MgO-Al2O3-SiO2-Cr2O3: An experimental study

Phase relationships in the system MgO-Al 2 O 3 -SiO 2 -Cr 2 O 3 (MASCr) were investigated experimentally from 1250 to 1560 °C using a 1-atm vertical quench furnace on 12 oxide mixtures covering a wide range of chemical compositions. Spinel, corundum, mullite, and sapphirine were found to display a wide range of solid solutions toward CR-rich end-members, whereas enstatite, cordierite, forsterite, and glasses were always Cr-poor. Glasses formed in relatively MgO-rich bulk compositions from 1250 °C, in assemblage with cordierite, enstatite, forsterite, and spinel, suggesting a lowering of the eutectic minimum in MASCr compared to available melting relationships in the model system MAS. Although unexpected, the relatively low-temperature melting of Cr-bearing mixtures is supported by topological constraints in the subsystems SACr and MSCr. The extent of Cr solubility in mullite has been found to reach ~14 wt% at 1560 °C, and 33 wt% in sapphirine at 1340 °C, which are the highest Cr values reported so far for these minerals. Liquidus surfaces are constrained by glass compositions that are displaced systematically toward silica compared to corresponding liquids in the ternary system MAS. As a consequence, the primary crystallization fields of Cr-spinel, Cr-sapphirine, and Cr-mullite are found to face the cristobalite/tridymite primary fields. A tentative liquidus diagram for the system MgO-Al 2 O 3 -SiO 2 -Cr 2 O 3 is proposed, which could serve as a basis for the interpretation of the high-temperature evolution of planetary materials as well as for the development of new ceramic materials.