Phase Diagrams of the Zr–Si–RE (RE=La and Er) Ternary Systems at 773?K (500?°C)

The isothermal sections of the phase diagram of the Zr–Si–RE (RE=La and Er) systems at 773 K (500 °C) have been investigated using X-ray power diffraction (XRD), scanning electron microscopy (SEM), and optical microscopy (OM) with the aid of metallographic analysis. The existences of 10 binary compounds, namely ZrSi₂, α-ZrSi, α-Zr₅Si₄, Zr₃Si₂, Zr₂Si, RESi₂, RESi_2–x , RESi, RE₅Si₄, and RE₅Si₃ have been confirmed in the Zr–Si–RE (RE=La and Er) systems, respectively. As for the reported binary compound RE₃Si₂, only La₃Si₂ has been observed in the Zr–Si–La system, whereas Er₃Si₂ was not found. No binary compound was found in the Zr–RE binary systems, and no ternary compound was found in the current ternary systems. None of the phases in Zr–Si–La system reveals a remarkable solid solution at 773 K (500 °C). However, the maximum solid solubility of Zr in Er, Er₅Si₃, Er₅Si₄, ErSi, ErSi_1.67, and ErSi₂ is determined to be approximately 12.0 at. pct, 2.4 at. pct, 3.0 at. pct, 3.3 at. pct, 2.2 at. pct, and 1.8 at. pct, respectively. The maximum solid solubility of Er in ErSi₂ is approximately 1.8 at. pct. No remarkable solid solubility of the elements in any of the other phases has been observed.     

The mineralogical characterization of tellurium in copper anodes

A mineralogical study of a «normal» commercial copper anode and six tellurium-rich copper anodes from the CCR Refinery of the Noranda Copper Smelting and Refining Company was carried out to identify the tellurium carriers and their relative abundances. In all the anodes, the major tellurium carrier is the Cu₂Se-Cu₂Te phase which occurs as a constituent of complex inclusions at the copper grain boundaries. In tellurium-rich anodes, the molar tellurium content of the Cu₂Se-Cu₂Te phase can exceed that of selenium. Although >85 pct of the tellurium occurs as the Cu₂Se-Cu₂Te phase, minor amounts are present in Cu-Pb-As-Bi-Sb oxide, Cu-Bi-As oxide, and Cu-Te-As oxide phases which form part of the grain-boundary inclusions. About 1 pct of the tellurium content of silver-rich anodes occurs in various silver alloys, but gold tellurides were never detected. Surprising is the fact that 2 to 8 pct of the total tellurium content of the anodes occurs in solid solution in the copper-metal matrix, and presumably, this form of tellurium dissolves at the anode interface during electrorefining.     

New luminescent 10-oxybenzoquinolate complexes of rare earth metals

A series of Sc,Y,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Ho,Er,Tm and Yb complexes with oxybenzoquinoline ligands(BQ) was synthesized by the reactions of 10-hydroxybenzo[h]quinoline with cyclopentadienides or tris(trimethylsilyl)amides of rare earth metals.The structure,as well as the photo-and electroluminescent(PL,EL) properties of these complexes in solutions and solid state were studied.In solutions,complexes of sodium and lanthanides exhibit double peaked ligand-centered PL of enol and keto forms of BQ with a...     

The solubility and solution behavior of antimony and tin in α-lron and the effects of nickel and chromium additions

The solid solubilities of Sn and Sb in α-Fe have been determined by means of lattice parameter measurements. The Sb solubility ranges from a maximum of 11 wt pct (5.4 at. pct) at 1000°C down to 5.3 wt pct (2.5 at. pet) at 600°C; the Sn solubility ranges from a maximum of 17.7 wt pct (9.2 at. pet) at 900°C to 6.5 wt pct (3.2 at. pet) at 600°C. These solubilities are remarkably large in view of the large sizes of the Sb and Sn atoms in relation to the Fe atom. It was not possible to rationalize the variation of the α-phase lattice parameter with Sb or Sn content from the point of view of atomic diameter or atomic volume. The addition of 1 wt pct Ni lowers the Sb solubility at 600°C from 5.3 to 3.5 wt pct (2.5 to 1.6 at. pet); the effect of Cr on the Sb solubility appears to be small. The addition of 1 wt pct Ni or 1 wt pct Cr lowers the Sn solubility from 6.5 to 5.2 wt pct (3.2 to 2.5 at. pet). It was found that a substantial amount of Ni substitutes for Fe in both the FeSb phase and the Fe₅Sn₃ phase. Formerly Research Fellow, Department of Metallurgy and Materials Science and LRSM, University of Pennsylvania     

Phase Equilibria of Sn-Co-Cu Ternary System

Sn-Co-Cu ternary alloys are promising lead-free solders, and isothermal sections of Sn-Co-Cu phase equilibria are fundamentally important for the alloys?? development and applications. Sn-Co-Cu ternary alloys were prepared and equilibrated at 523?K, 1073?K, and 1273?K (250?°C, 800?°C, and 1000?°C), and the equilibrium phases were experimentally determined. In addition to the terminal solid solutions and binary intermetallic compounds, a new ternary compound, Sn₃Co₂Cu₈, was found. The solubilities of Cu in the ??-CoSn₃ and CoSn₂ phases at 523?K (250?°C) are 4.2 and 1.6?at. pct, respectively, while the Cu solubility in the ??-Co₃Sn₂ phase is as high as 20.0?at. pct. The Cu solubility increases with temperature and is around 30.0?at. pct in the ??-Co₃Sn_2?at 1073?K (800?°C). The Co solubility in the ??-Cu₆Sn₅ phase is also significant and is 15.5?at. pct at 523?K (250?°C).     

Representation of the solubility of lead chloride in various chloride solutions with Pitzer’s model

A modified Pitzer’s model^[6] has been applied to the representation of the activities of various species in chloride solutions of lead (II). The parameters associated with the representation were the formation constants of four lead chlorocomplexes as well as Pitzer’s interaction parameters. [7] They were determined by treatment of a data base composed of experimental solubilities of lead in NaCl, NH₄C1, and HC1 solutions at 25 °C. The root mean square (rms) relative deviations obtained for the representation of the experimental solubilities were 7.8 pct, 5.6 pct, and 5.6 pct for the three systems, respectively. The extension of the model to solubilities in a NaClO₄-NaCl solution at an apparent ionic strength of 4 mol/kg water gives a rms relative deviation of 8.9 pct if one parameter involving the perchlorate anion is adjusted. A data treatment of experimental solubilities at other temperatures (from 13 °C to 100 °C) for the systems PbCl₂-NaCl-H₂O and PbCl₂-NH₄Cl-H₂O has been made to determine the temperature derivatives of Pitzer’s parameters involving complexed ions as well as the variation of solubility and complexation constants with temperature. The resulting rms relative deviation is 9.8 pct.     

Measurement of solid solubility of germanium in aluminum

The solid solubility of Ge in aluminum was determined by resistivity measurement at 77 K of Al-Ge alloys annealed at various temperatures for times sufficient to complete the precipitation of the equilibrium Ge phase. The solid solubility of Ge in aluminum was found to vary from 0.252 at. pct at 533 K to 1.82 at. pct at 693 K. From the temperature dependence of the solid solubilities, the excess entropy of mixing ΔS and heat of mixing ΔH associated with the formation of solid solution of Ge in aluminum were calculated to be 2.77 R and 38.5 kJ mol^-1, respectively. Using these values of ΔS and ΔH, the maximum solid solubility of Ge in aluminum was calculated to be 2.08 at. pct at the eutectic temperature 697 K. The magnitude Δρ _Ge ⁷⁷ /Δc due to 1 at. pct impurity was determined to be 8.60 nΩm/at. pct Ge. The resistivity of Al-1.32 at. pct Ge alloys aged at 573 and 623 K was measured at 77 K to determine the time variation of the average concentrationc of the solute in the matrix during coarsening of the Ge precipitates. The value ofc, calculated using the value of Δρ _Ge ⁷⁷ /Δc, decreased linearly in accordance with the t^-1/3 law. The concentration of the solute in the matrix, in equilibrium with the Ge particle of infinite size, was determined by extrapolating thec vs t^-1/3 plot to infinite time, in excellent agreement with the above solid solubility. Formerly Graduate Student, Department of Materials Science, Tohoku University     

The Gd-Yb and Lu-Yb phase systems

The Gd-Yb and Lu-Yb phase systems were established by thermal analysis, X-ray diffrac-tion, metallography, electron microprobe and chemical analyses. The solubility of Yb in α-Gd ranges from 6.5 at. pct at 500°C to 19.0 at. pct at 1161°C. The addition of Yb to Gd lowers theβ (bec) to α (hcp) transformation temperature to an inverse peritectic reaction at 20.0 at. pct Yb and 1161°C. The addition of Yb to Gd lowers the melting point of Gd to a monotectic horizontal at 1183°C which extends from 21.0 to 71.0 at. pct Yb. The monotec-tic composition is 49.0 at. pct Yb. The solid solubility of Gd in Yb ranges from 0.2 at. pct at 500°C to 2.3 at. pct at 819°C. The melting point of Yb is raised from 816°C to 819°C by the addition of Gd while the γ (bee) toβ (fee) transformation temperature of Yb is lowered from 796°C to 780°C by the addition of Gd. The solubility of Yb in solid Lu ranges from 6.0 at. pct at 800°C to 15 at. pct at 1530°C. The addition of Yb to Lu lowers the melting point of Lu to a monotectic horizontal at 1530°C which extends from 15 to 90 at. pct Yb. The monotectic composition is approximately 30 at. pct Yb. The solid solubility of Lu in Yb ranges from less than 0.1 at. pct at 500°C to 0.3 at. pct at 817°C. The addition of Lu raises the melting point of Yb to 817°C and also raises theβ (fee) to y (bec) transformation temperature to 798°C.     

A mineralogical study of the deportment and reaction of silver during copper electrorefining

The majority (>95 pct) of the silver in copper anodes occurs in metastable solid solution in the copper matrix; only a small percentage is present in solid solution in Cu₂(Se,Te) inclusions, as a constituent of complex Cu-Pb-As-Sb-Bi oxides or as tiny grains of Ag-Cu alloy. During elec-trorefining, the silver in the copper matrix dissolves, but it is rapidly removed from the elec-trolyte by a variety of reactions. Part of the silver is precipitated in elemental form by cuprous ion, but some of this metallic silver subsequently redissolves. Some of the dissolved silver precipitates as a complex Cu-Ag-Pb-As-Se oxidate phase which agglomerates the particles in the anode slimes, and some reacts with the Cu₂(Se,Te) inclusions liberated from the anode to form, sequentially, silver-bearing copper selenide, AgCuSe, copper-bearing silver selenide, and Ag₂Se. Several selenide species are present in the anode slimes, and individual selenide particles com-monly consist of more than one selenide species. Because of the diversity and complexity of the silver-bearing phases present, the Ag/Se ratio in the anode is only an approximate indicator of the selenide species present in the anode slimes.     

Sulfide and sulfate solid solubility in lime,magnesia, and calcined dolomite: Part I. CaS and CaSO4 solubility in CaO

In the present work the solid solubilities of CaS and CaSQ, in burnt lime were investigated by equilibrating lime with CO-CO₂-SO₂ mixtures at temperatures from 950 to 1300°C. Also, the equilibrium constants for the formation of CaS and CaSO₄ were determined. At high oxy-gen activities, corresponding to a CO₂/CO ratio >100 in the gas, the sulfur dissolves in lime primarily as sulfate ions. At lower oxygen activities (CO₂/CO <30), the sulfur goes into so-lution in lime essentially as sulfide ions. Over the temperature range investigated the limit-ing sulfide solubility is within 0.01 to 0.03 pct S, whereas the sulfate solubility is within 0.03 to 0.1 pct S, increasing with increasing temperature. An erratum to this article is available at .     

The stacking fault probabilities and lattice spacings of silver-rich Ag−Pd−Cd alloys

The deformation stacking fault parameter, α, has been determined from X-ray peak shift measurements on filings of silver-rich Ag?Pd?Cd solid solutions. In the Ag?Cd binary alloys, α increases exponentially with the cadmium content, from 3×10^?3 for pure silver to 19×10^?3 for 80Ag?20Cd. As palladium is added to the Ag?Cd binary alloy, α decreases in such a manner that the effect of cadmium is counter-balanced by palladium until both are present in equal proportions and, thereafter, α remains constant. The results are compared with previous determinations on other binary alloys. The lattice parameter,a, also has been measured on annealed samples.a increases linearly with cadmium up to 20 at. pct Cd. As palladium is added to the Ag?Cd alloy,a decreases more rapidly than it increases with cadmium. The rate of decrease becomes less rapid when palladium is present in excess of cadmium.     

Solubility of some transition metal oxides in cryolite-alumina melts: Part I. Solubility of FeO,FeAl2O4, NiO,and NiAl2O4

The solubilities of FeO, FeAl₂O₄, NiO, and NiAl₂O₄ were measured in cryolite-alumina melts at 1020 °C. FeO was found to be the stable solid phase at alumina concentrations below 5.0 wt pct, while FeAl₂O₄ was stable above that. The corresponding figure for the nickel system was 3.0 wt pct Al₂O₃. These values correspond to Gibbs energies of formation of the aluminates (from the constituent oxides) of −17.6 and −29 kJ/mol, respectively. In alumina-saturated melts in the range 980 to 1050 °C, the solubilities of both aluminates increased with increasing temperature, the apparent enthalpies of solution being 65 kJ/mol for FeAl₂O₄, and 249 kJ/mol for NiAl₂O₄. Investigation of the solubilities of the aluminates as a function of the NaF/AlF₃ ratio in alumina-saturated melts at 1020 °C showed maxima at a molar ratio of around 5. The results are discussed in terms of the species apparently existing in the solution, and are consistent with the solute species being fluorides, not oxyfluorides. The activity coefficients of FeF₂ (liquid) and NiF₂ (solid) in dilute solution in cryolite are found to be 0.22 and 1.2, respectively.     

The thermodynamic properties of liquid Ag−Si alloys

The vapor transportation method was used to determine the partial pressure of silver above molten Ag?Si solutions in the temperature range of 1450° to 1600°C. With the use of previously determined values for the partial pressure of liquid pure silver, values for the activity of silver were calculated and fitted to the orthogonal polynomial “Z-series” recently developed by Williams to represent the thermodynamic behavior of binary solutions. The silicon properties were determined analytically using the Gibbs-Duhem equation and the coefficients obtained from the silver data. Silver was found to exhibit positive deviations from ideality in alloys containing less than about 50 at. pct Ag. In the silver-rich solutions, silver showed negative deviations from Raoult's law. However, at 1550° and 1600°C, the negative silver departures were quite small. Within the limit of experimental error, silicon showed positive deviations from ideality at all temperatures studied for alloys containing more than 10 at. pct Si. At infinite dilution the silicon deviations were quite small. Regular solution behavior cannot describe the thermodynamics of liquid Ag?Si alloys.     

Lead solubility in FeO x -CaO-SiO2 slags at iron saturation

Experiments have been carried out to determine the equilibria between FeO _x -CaO-SiO₂ slag and lead metal in iron crucibles at temperatures ranging from 1473 to 1573 K. It has been found that the highest lead solubilities are observed in the silica-saturated iron silicate slags, while the lowest solubilities are observed in the CaO-saturated calcium ferrite slags. The activity coefficient of PbO varies from 0.15 to 3, depending on the slag composition. Changes in temperature do not have a significant impact on the activity coefficient. The activity of FeO and pct Fe³⁺/pct Fe²⁺ ratios have been determined as a function of slag composition. These new experimental data have been incorporated into an optimized thermodynamic slag model using the computer package FACT.     

Boron removal by titanium addition in solidification refining of silicon with Si-Al melt

In order to effectively remove B from Si for its use in solar cells, a process involving B removal by solidification refining of Si using a Si-Al melt with Ti addition was investigated. For clarifying the effect of Ti addition on B removal from the Si-Al melt, TiB₂ solubilities in Si-64.6 at. pct Al melt at 1173 K and Si-60.0 at. pct Al melt at 1273 K were determined by measuring the equilibrium concentrations of B and Ti in the presence of TiB₂ precipitates. The small solubilities of TiB₂ in the Si-Al melt indicate the effective removal of B from the Si-Al melt by Ti addition. Further, solidification experiments of Si-Al alloys containing B by Ti addition were performed, and the effect of Ti addition on the solidification refining of Si with the Si-Al melt was successfully confirmed.     

Distribution of Gold and Silver between Copper and Matte

The distribution coefficients of silver and gold between copper and matte phases have been measured at 1400 and 1500 K. For 0.07 to 0.13 wt pct silver and 0.0022 to 0.0042 wt pct gold in ironfree matte, the distribution coefficients of silver and gold are independent of concentration. For iron-bearing matte, the distribution coefficients of silver and gold are correlated with iron content of the matte. From the measured values of the distribution coefficients of silver and gold, the activity coefficients of AgS_0.5 and Au in copper-saturated matte have been calculated. The following correlations express these results: log γ°_AgS0.5(1) = -425/T - 0.074 + 0.09N_FeS, log γ°_Au(1) =-7620/T + 7.25 forT = 1400 to 1500 K and N_FeS, mole fraction of FeS = 0 to 0.28. The present values of the activity coefficients of AgS_0.5 must be used exclusively in conjunction with the following Gibbs free energy of formation: 2Ag(l) + 1/2S₂(g) = Ag₂S(l), ΔG° = -23960 + 10.295T (cal/mol). M. Nagamori, formerly Associate Professor of Metallurgy at The University of Utah.     

Determination of Solid Fraction from Cooling Curve

A new method to determine directly the solid fraction using the cooling curve was proposed for solidification of undercooled melts. Then, to construct three different baselines, a sudden function ξ _α (x) is introduced. In terms of the ξ _α (x) function, accordingly, the solid fractions during solidification of Ni-3.3 wt pct B, Al-7 wt pct Si, Al-14 wt pct Cu, and Fe-4.56 wt pct Ni alloys were predicted. The predictions of the primary, the regular lamellar eutectic, the anomalous eutectic, and the peritectic phases from cooling curves of the solidified samples coincide with the results of measurement or the available methods.     

The accumulation of the rare earth elements and of scandium in successive needle age classes of Norway spruce

The endogenous concentrations of Sc, La, Ce, Sm, Eu, Tb, Yb, and Lu were determined by neutron activation analysis in up to five successive needle age classes of Norway spruce (Picea abies). Trees from nine sites over different bedrocks were sampled individually. Concentration values found are generally much lower than those reported in the literature. This is attributed to the careful removal of any aerosols or soil particles from the needle surface prior to analysis. The concentration of each element increases linearly with the needle age class, i.e., the accumulation can be characterized by just one parameter, the yearly increment. This pattern is followed at small as well as at large concentrations. The accumulation behavior of the investigated elements is identical to that of Si. The relative concentrations of the rare earth elements (REE) in the needles are similar to those in the earth crust. There are significant correlations between the individual REE and between Sc and La.