Nonstoichiometric Solid Solutions Research Articles

Synthesis, characterization, and structural analysis of (1-x) Eu2Ti2O7 – x ZnO solid solution with a pyrochlore structure: Insights for potential applications in hydrogen storage systems

This study focuses on the synthesis and characterization of a (1-x) Eu2Ti2O7 – x ZnO solid solution with a pyrochlore structure using a solid-state method. The structural investigations of the prepared materials were carried out using powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared (FT-IR), and Raman spectroscopy. These techniques confirmed the successful formation of a new non-stoichiometric solid solution with a pyrochlore structure within the compositional range of 0 ≤ x ≤ 0.33, maintaining a cubic structure with the Fd-3m space group. A slight increase in the lattice parameter, a, was observed with higher substitution levels, x. Quantitative analysis using FullProf software revealed the substitution of Zn2+ ions on both Eu3+ and Ti4+ sites, with non-equivalent proportions, leading to vacancies in the anionic sublattice. Furthermore, the electrochemical hydrogen storage (EHS) capacity of these materials was examined. The pyrochlore solid solution with x = 0.25 exhibited an outstanding discharge capacity of about 1400 mAh/g, surpassing that of other samples. This finding highlights its high potential for hydrogen storage. Consequently, our research yields valuable insights into the synthesis, structural properties, and electrochemical performance of the (1-x) Eu2Ti2O7 – x ZnO solid solution, opening up new possibilities for hydrogen storage.

Numerical Simulation of CdTe Crystal Growth Using the Vertical Gradient Freeze Technique Assisted by Axial Low-Frequency Oscillations of the Melt

The problem of intensification of the melt crystal growth process has been analyzed using CdTe as an actual material. Numerical simulation of 100 mm diameter CdTe crystal growth using the VGF technique has been carried out. The heat–mass transfer was controlled by introducing low-frequency oscillating baffle into the melt, which is a so-called axial vibrational control (AVC) technique. The baffle configuration has been optimized to destroy solid “tails”, which were formed near the crucible walls at high cooling rates due to the low thermoconductivity and the corresponding latent heat. Analysis of CdTe homogeneity range showed that during fast crystal cooling, Te micro precipitations were formed, resulting from the decay of oversaturated Cd-rich nonstoichiometric solid solution during the Bridgman crystal growth technique. After full crystallization, a VGF-grown CdTe crystal stays inside the phase field of the high-temperature wurtzite polymorph. This makes it possible to go through the polymorph transition without Te micro-precipitating using the advantages of the VGF-specific feature of very slow cooling.

Order-Disorder in the Structures of Lithium Aluminosilicate Minerals by XRD and Multinuclear NMR

The crystal structures of the lithium aluminosilicate minerals of the Li2O–Al2O3–SiO2 (LAS) system (Li1−xAl1−xSi1+xO4 system for 0.0 ≤ x ≤ 1.0), and bikitaite were determined by X-ray diffraction (XRD) in literature, suggesting several possible lattice models for each of the crystallized phases, because of the intrinsic experimental difficulties of this technique. Here, we correlate powder XRD patterns with Rietveld refinement of cell parameters and magic angle sample spinning multinuclear magnetic resonance (NMR) spectra, including 29Si, 27Al, 7Li, and 6Li spectroscopy at 7.05 T, 9.4 T, and 20 T. The aim is to select appropriate lattice models from short-range order schemes in the lithium aluminosilicate phases, from natural minerals and synthetic crystals from the crystallization of amorphous gel precursors by a ceramic route and also by hydrothermal high-pressure experiments. Solid solutions were found in α-quartz and α-cristobalite up to x ≥ 0.75, and in β-eucryptite and β-spodumene for 0.0 ≤ x ≤ 1.0, when the ceramic synthesis is at work. The local structures of these intermediate members of the β-eucryptite and β-spodumene solid-solution series have 29Si NMR spectra consistent with the Loewenstein’s rule, i.e., they have short-range order but are strictly non-periodic structures. However, β-eucryptite LiAlSiO4 end-member has a short-range structure compatible with the long-range order of the P6422 symmetry, when the crystallization is produced at hydrothermal conditions. The local structure of α-spodumene LiAlSi2O6 is consistent with the C2/c model. α-eucryptite LiAlSiO4 shows a short-range structure as that suggested by the R-3 lattice model. Petalite LiAlSi4O10 has a local structure compatible with the P2/a space group. Finally, the 29Si NMR spectra of bikitaite LiAlSi2O6·H2O indicate a short-range structure well-suited with the P1 symmetry. These results are consistent with the Ostwald‘s rule of stages, forming a order-disorder sequence of increasing long-range order from the starting fully disordered solid gels, through crystalline pseudoperiodic structures in non-stoichiometric solid solution crystals that respect the Lowenstein’s rule, up to fully ordered crystals with short-range structures from NMR close to the long-range structures by XRD, as in the stoichiometric compounds found in some natural minerals.

Structural properties and spontaneous polarization behaviour in Cu-doped LiTaO3

In this work, we have study theoretically the effect of cooling modes on the changes of spontaneous polarisation (Ps) of non-stoichiometric solid solutions of Cu-doped LiTaO3 in correlation with the defects structure. The changes of spontaneous polarization in rapid and slow cooling modes with the rate of % Cu2+ and with the Curie temperature, allows us to analyse the defect structure of solid solutions synthesized in ternary system Li2O-Ta2O5-(CuO)2 in vicinity of LiTaO3. The theoretical results obtained by application of our approach combined with the proposed vacancy models; show that the cooling modes have an effect on the spontaneous polarization, consequently on the defects structure of Cu-doped LiTaO3. In other hand, the proposed vacancy models investigated by our theoretical approach are able to describe the defect structure and the substitution mechanism in each solid solutions of Cu-doped lithium tantalate.

Unconventional high permittivity and relaxor like anomaly in (Sr, Ce, Pr)TiO3 solid solution

In this study, non-stoichiometric solid solution, Sr1–1.5(x+y)CexPryTiO3 abbreviated as (Sr, Ce, Pr)TiO3 (with 0.05 ≤ x ≤ 0.35 and y = 0.05, sintered in N2/H2 with 99% N2 and 1% H2) were prepared via a conventional solid-state method. By introducing (Ce0.25Pr0.05)3+/4+ on the A-site, the structure symmetry of the ceramic could be reduced, confirming cubic to tetragonal phase transition. Using Rietveld refinement and electron diffraction (TEM), the tetragonal phase was assigned to P4/mmm space group which posses a center of symmetry (centrosymmetric tetragonal unit cell). A small opening of hysteresis loop at higher Ce doping is assumed to be a caused by defect dipoles and conductivity. The dielectric anomalies were observed in all compositions, therefore, we assume that they are not related to structural phase transition but rather to some conductivity processes.

Passivation Phenomena in Single Phase High Entropy Alloys: The Evolution of Oxide Composition in Chloride

High entropy alloys (HEAs), sometimes known more broadly as compositionally complex alloys (CCAs) are emerging materials that have recently attracted great interest due to their potentially attractive properties. This class of alloys deviates from traditional alloys by containing five or more alloying elements which results in a high entropy of mixing promoting the formation of a solid solution alloy [1-3]. Initial electrochemical testing and characterization of HEAs revealed excellent passivity and resistance to local corrosion[3-6]. For some HEAs, a non-stoichiometric solid solution oxide forms during fast passivation. In this case, all alloying elements may be oxidized if the passivation potential is far from equilibrium. Also, some elements will dissolve preferentially at the oxide/electrolyte interface leading to an enrichment of other alloying elements in the passivating oxide[4]. The focus of this study is to understand the evolution of the electrochemically grown oxide formed on solid solution HEAs: Ni38Fe20Cr21Ru13Mo6W2 and Ni38Fe20Cr22Mn10Co10 within a slightly acidic Cl- environment. Results are compared to a conventional Ni-20Cr binary alloy. This study attempts to establish the fate of the alloying elements with respect to the outer and inner layers of the oxide, whether enriched or depleted at the oxide metal interface, or preferentially dissolved into solution. The E-log(i) behavior was first characterized on the HEA within a chloride environment enabling the identification of the passive current density, pitting potential, and repassivation potential. Passive films were electrochemically grown on alloy surfaces utilizing a potential hold for times ranging from 102 to 105 seconds within the passive region. In-situ analysis was conducted using AESEC, AC as well as DC electrochemistry methods to monitor passive current density, oxide thickness, and cation dissolution into solution. Ex-situ analysis was utilized to characterize the passive film and consisted of the following: 3D-atom probe tomography and X-ray photoelectron spectroscopy. Results are compared against theories such as non-equilibrium solute capture compared to thermodynamic expectations as well as enrichment models such as those proposed by Grimal and Marcus, Kirchheim, and others[7-9]. Acknowledgements This work was supported as part of the Center of Performance and Design of Nuclear Waste Forms and Containers, an Energy Frontier Research Center funded by the U.S. Department of Energy, Office of Science, Basic Energy Sciences under Award # DE-SC0016584 References [1] Y. Qiu, M.A. Gibson, H.L. Fraser, N. Birbilis, Corrosion characteristics of high entropy alloys, Materials Science and Technology, 31 (2015) 1235-1243. [2] Y. Qiu, S. Thomas, M.A. Gibson, H.L. Fraser, N. Birbilis, Corrosion of high entropy alloys, npj Materials Degradation, 1 (2017) 15. [3] M.H. Tsai, J.W. Yeh, High-Entropy Alloys: A Critical Review, Materials Research Letters, 2 (2014) 107-123. [4] K.F. Quiambao, S.J. McDonnell, D.K. Schreiber, A.Y. Gerard, K.M. Freedy, P. Lu, J.E. Saal, G.S. Frankel, J.R. Scully, Passivation of a corrosion resistant high entropy alloy in non-oxidizing sulfate solutions, Acta Materialia, 164 (2019) 362-376. [5] Tianshu Li, Orion J. Swanson, G.S. Frankel, Angela Y. Gerard, Pin Lu, James E. Saal, J.R. Scully, Localized corrosion behavior of a single-phase non-equimolar high entropy alloy, Electrochimica Acta, 306 (2019) 71-84. [6] P. Lu, J.E. Saal, G.B. Olson, T.S. Li, O.J. Swanson, G.S. Frankel, A.Y. Gerard, K.F. Quiambao, J.R. Scully, Computational materials design of a corrosion resistant high entropy alloy for harsh environments, Scripta Mater, 153 (2018) 19-22. [7] J.E. Castle, K. Asami, A more general method for ranking the enrichment of alloying elements in passivation films, Surface and Interface Analysis, 36 (2004) 220-224. [8] R. Kirchheim, B. Heine, H. Fischmeister, S. Hofmann, H. Knote, U. Stolz, The passivity of iron-chromium alloys, Corrosion Science, 29 (1989) 899-917. [9] P. Marcus, J.M. Grimal, The anodic dissolution and passivation of NiCrFe alloys studied by ESCA, Corrosion Science, 33 (1992) 805-814.

Effect of cooling modes on defect structure in Cu-doped LiTaO3

In this work we have study the defects structure of non-stoichiometric solid solutions of Cu-doped LiTaO3, the changes of Curie temperature with rate of % Cu2+ (mol) in rapid and slow cooling modes, allows us to analyze the defect structure of solid solutions synthesized in ternary system Li2O–Ta2O5–(CuO)2 in vicinity of LiTaO3. A simple comparison between our theoretical results and the experimental data of Tc shows that there is a cooling mode effect on the structural properties of Cu-doped LiTaO3. Consequently, our proposed models are able to describe the defect structure of Cu-doped lithium tantalate.

In Operando Analysis of Passive Film Growth on Ni-Cr and Ni-Cr-Mo Alloys in Chloride Solutions

The instantaneous kinetics of oxide formation and growth, in competition with passive film dissolution and breakdown, were investigated for Ni-22 Cr and Ni-22 Cr-6 Mo (wt%) during single step passivation at +0.2 VSCE. Experiments were conducted in selected acidic and alkaline chloride-containing environments using simultaneous AC and DC electrochemistry; including on-line Inductively Coupled Plasma-Mass Spectrometry (ICP-MS). In parallel experiments, in-situ neutron reflectometry (NR) and ex-situ X-ray photoelectron spectroscopy (XPS) were utilized to characterize the formation of surface oxide films as a function of time. The specific roles of pH and Mo during passivation and breakdown kinetics are highlighted, providing an insight into the fate of the elements which comprise the alloys, and their effects on passivation behavior. It was observed that early oxidation of both Ni and Cr-species occurred in acidic electrolyte. Preferential dissolution of Ni2+ at later times enabled gradual Cr3+ enrichment within the surface film. However, greater relative stability of NiO and Ni(OH)2 was observed in the alkaline condition. Upon alloying Ni-Cr with Mo, Cr3+ became increasingly enriched in the surface film during anodic polarization. Oxides were interpreted to consist of non-stoichiometric solid solutions formed via solute capture.

Capabilities of X-ray diffuse scattering method for study of microdefects in semiconductor crystals

The capabilities of X-ray diffuse scattering (XRDS) method for the study of microdefects in semiconductor crystals have been overviewed. Analysis of the results has shown that the XRDS method is a highly sensitive and information valuable tool for studying early stages of solid solution decomposition in semiconductors. A review of the results relating to the methodological aspect has shown that the most consistent approach is a combination of XRDS with precision lattice parameter measurements. It allows one to detect decomposition stages that cannot be visualized using transmission electron microscopy (TEM) and moreover to draw conclusions as to microdefect formation mechanisms. TEM-invisible defects that are coherent with the matrix and have smeared boundaries with low displacement field gradients may form due to transmutation doping as a result of neutron irradiation and relaxation of disordered regions accompanied by redistribution of point defects and annihilation of interstitial defects and vacancies. For GaP and InP examples, a structural microdefect formation mechanism has been revealed associated with the interaction of defects forming during the decomposition and residual intrinsic defects. Analysis of XRDS intensity distribution around the reciprocal lattice site and the related evolution of lattice constant allows detecting different decomposition stages: first, the formation of a solution of Frenkel pairs in which concentration fluctuations develop, then the formation of matrix-coherent microdefects and finally coherency violation and the formation of defects with sharp boundaries. Fundamentally, the latter defects can be precipitating particles. Study of the evolution of diffuse scattering iso-intensity curves in GaP, GaAs(Si) and Si(O) has allowed tracing the evolution of microdefects from matrix-coherent ones to microdefects with smeared coherency resulting from microdefect growth during the decomposition of non-stoichiometric solid solutions heavily supersaturated with intrinsic (or impurity) components.

Analysis of Correlation between Density Variations and Defect Structure of W6+ : LiTaO3

We investigate the defect structure of non-stoichiometric solid solutions of WO3-doped LiTaO3 in correlation with the evolution of the density within our theoretical approach. The dopant concentration and the mechanism of substitution, which depends of the ionic rays of different cations that exit into the network, have an effect on crystalline parameters and, consequently, on the density. In order to explain the defect structure of solid solutions synthesized in the ternary system Li2O–Ta2O5–(WO3)2 in a vicinity of LiTaO3,, we have shown a convergence between theoretical and experimental results by the application of our theoretical approach combined with the new proposed vacancy models. We conclude that the new vacancy models are able to describe the defect structure and the substitution mechanism in each solid solutions of WO3-doped lithium tantalate.

Phase formation and microstructure in lithium-carbon intercalation compounds during lithium uptake and release

Abstract The intercalation and de-intercalation behavior of lithium in graphite was investigated with respect to the formation of lithium graphite intercalation compounds (Li-GICs) using a combination of XRD measurements and metallography. Microstructural features and the evolution of phases and structural details of Li-GICs during Li uptake and release are correlated for the first time, giving new insight into the formation of Li-GICs. Lithium evaporation loss during annealing was exploited for studying the phase evolution during lithium de-intercalation, whereas phase formation during lithium uptake was studied in a sample exhibiting a lithium concentration gradient. The experiments indicate that growth and dissolution of the compound LiC6 do not occur by an inverse mechanism, as shown by the formation of different intermediate phases. The compound LiC12 was found to be a non-stoichiometric solid solution. LiC6 can be clearly identified in micrographs by the color and distinct phase boundaries, while LiC12 is situated in the vicinity of the LiC6 phase with varying coloration depending on the Li content.

Effect of the Addition of Al Power on the Microstructure and Phase Constitution of Al<sub>2</sub>O<sub>3</sub>-MgO Composites Sintered at 1700°C under N<sub>2</sub> Atmosphere

Al2O3-MgO-Al composites were prepared by sintering in carbon tube furnace at 1700°C under nitrogen atmosphere with tabular alumina, sintered magnesia and aluminum powder as raw materials. Effect of Al powder content on the porosity, microstructure and phase constitution of Al-Al2O3-MgO composites were investigated. The results show that the main phase was non-stoichiometric spinel solid solution, and a little AlN, AlON and MgAlON were detected by XRD. With Al power content increasing, the amount of the porosity and AlN, AlON and MgAlON around the porosity detected by SEM increased. These new phases enhance the combination of the large particles and the matrix.

Lattice Parameter Behavior with Different Nd and O Concentrations in (U1−yNdy)O2±X Solid Solution

The solid solution of (U1−yFPy)O2±x has the same fluorite structure as UO2±x, and the lattice parameter is affected by dissolved fission product and oxygen concentrations. The relation between the lattice parameter and the concentrations of neodymium and oxygen in the fluorite structure of (U1−yNdy)O2±x was investigated using X-ray diffraction. The lattice parameter behavior in the (U1−yNdy)O2±x solid solution shows a linear change as a function of the oxygen-to-metal ratio and solubility of neodymium. The lattice parameter depends on the radii of ions forming the fluorite structure and also can be expressed by a particular rule (modified Vegard’s law). The numerical analyses of the lattice parameters for the stoichiometric and nonstoichiometric solid solutions were conducted, and the lattice parameter model for the (U1−yNdy)O2±x solid solution was assessed. A very linear relationship between the lattice parameter and the Nd and O concentration for the stoichiometry and nonstoichiometry of the (U1−yNdy)O2±x solid solution was verified.

Thermal decomposition of sodium amide, NaNH2, and sodium amide hydroxide composites, NaNH2-NaOH.

Sodium amide, NaNH2, has recently been shown to be a useful catalyst to decompose NH3 into H2 and N2, however, sodium hydroxide is omnipresent and commercially available NaNH2 usually contains impurities of NaOH (<2%). The thermal decomposition of NaNH2 and NaNH2-NaOH composites is systematically investigated and discussed. NaNH2 is partially dissolved in NaOH at T > 100 °C, forming a non-stoichiometric solid solution of Na(OH)1-x(NH2)x (0 < x < ∼0.30), which crystallizes in an orthorhombic unit cell with the space group P212121 determined by synchrotron powder X-ray diffraction. The composite xNaNH2-(1 - x)NaOH (∼0.70 < x < 0.72) shows a lowered melting point, ∼160 °C, compared to 200 and 318 °C for neat NaNH2 and NaOH, respectively. We report that 0.36 mol of NH3 per mol of NaNH2 is released below 400 °C during heating in an argon atmosphere, initiated at its melting point, T = 200 °C, possibly due to the formation of the mixed sodium amide imide solid solution. Furthermore, NaOH reacts with NaNH2 at elevated temperatures and provides the release of additional NH3.

Superior catalytic performance of non-stoichiometric solid solution Ce1 − xCuxO2 − δ supported copper catalysts used for CO preferential oxidation

A series of Ce1−xCuxO2−δ non-stoichiometric solid solutions and their supported copper catalysts CuO/Ce1−xCuxO2−δ (x=0, 0.005, 0.022, 0.043) were prepared by co-precipitation and deposition–precipitation, respectively. The CuO/Ce1−xCuxO2−δ catalysts show high performance for CO preferential oxidation (CO PROX). Multiple techniques of N2 sorption (BET), XRD, Laser Raman spectroscopy (LRS), HRTEM, H2-TPR, O2-TPO, N2O chemisorption and in-situ DRIFTS were used for catalyst characterization. The results of XRD, LRS and H2-TPR conformably indicate that a small amount of Cu2+ ions can be incorporated into the lattice of CeO2, forming non-stoichiometric solid solutions Ce1−xCuxO2−δ, which shows much better reducibility than pure CeO2. The supported CuO/Ce1−xCuxO2−δ catalysts exhibit remarkably enhanced activity for CO PROX as compared with CuO/CeO2, especially the catalyst CuO/Ce0.978Cu0.022O2−δ containing 15% Cu, which displays the best CO PROX performance, showing not only the lowest temperature (115°C) for CO total conversion, but also the 100% selectivity of O2 to CO2 at this temperature. Several aspects including the presence of more oxygen vacancies, the improved reducibility, and stronger capability for CO chemisorption of this catalyst account well for its superior performance for CO PROX. Based upon the in-situ DRIFTS study, it is revealed that Cu+ is the main active site for CO oxidation, while Cu0 is more active for H2 activation and oxidation.

Structural determination of new solid solutions [Y2-xMx][Sn2-xMx]o7-3x/2 (M = Mg or Zn) by Rietveld method

New [Y2-xMx][Sn2-xMx]O7-3x/2 (0 ?x? 0.30 for M = Mg and 0 ?x? 0.36 for M = Zn) solid solutions with the pyrochlore structure were synthesized via high-temperature solid-state reaction method. Powder X-ray diffraction (PXRD) patterns and Fourier transform infrared (FT-IR) spectra showed that these materials are new non-stoichiometric solid solutions with the pyrochlore type structure. The structural parameters for the solids obtained were successfully determined by Rietveld refinement based on the analysis of the PXRD diagrams. Lattice parameter (a) of these solid solutions decreases when x increases in both series. All samples obtained have the pyrochlore structure Fd-3m, no. 227 (origin at center -3m) with M2+ (M = Mg2+ or Zn2+) cations in Y3+ and Sn4+ sites, thus creating vacancies in the anionic sublattice.

X-ray Rietveld analysis and Fourier transform infrared spectra of the solid solutions [Eu 2− xM x][Sn 2− xM x]O 7−3 x/2 (M = Mg or Zn)

Two series of mixed oxides with formula [Eu 2− x M x ][Sn 2− x M x ]O 7−3 x/2 (M = Mg or Zn) have been synthesized. The study by X-ray diffraction and Fourier transform infrared spectroscopy shows that the solids obtained are new non-stoichiometric solid solutions with the pyrochlore type structure. For both series a decrease of the cell parameter is observed when the degree of substitution, x, increases. The structural refinements (X-ray studies) were achieved in the space group Fd-3 m, no. 227 (origin at center -3 m) by using the Fullprof software. The Rietveld refinements show that the divalent cations M 2+ (Mg 2+, Zn 2+) substitute isomorphically for Eu 3+ and Sn 4+ ions producing vacancies in the anionic sublattice.

Raman study of LiTaO 3-related non-stoichiometric solid solutions isolated inside the ternary systems Li 2O–Ta 2O 5–(M′O) 2 with M′=Mn, Co

We have characterized by Raman spectroscopy the disorder and the local modifications of cation environment in the lithium tantalate structure resulting from the incorporation of bivalent cations Co 2+ and Mn 2+ as potential substitutes for Li and/or Ta ions. Frequency and damping of the E(TO1), E(TO6) and E(TO8) phonon modes of ceramic powders are studied along seven lines in the ternary phase diagrams Li 2O–Ta 2O 5–(M′O) 2 with M′=Mn and Co, and compared to those of the pure stoichiometric LiTaO 3. Raman spectroscopy is found to be very sensitive to the substitution ions and defects generated in the lattice vibration. Dopants occupy primarily the Li site in the region of lithium oxide excess. The site of Ta becomes progressively implicated in the substitution process when the concentration of dopant increases. In the Li-poor region of the ternary-phase diagram, corresponding to under-stoichiometric compositions, we retain the charge compensation mechanism involving both Li and Ta site according to: 3Li ++Ta 5+→4M′ 2+ with M′ 2+=Mn 2+ or Co 2+.

Thermoelectric properties of alkaline earth ruthenates prepared by SPS

Alkaline earth ruthenates ARuO 3 ( A = Ca, Sr and Ba) and Sr 2RuO 4 in a single phase were obtained at molar ratio of Ru to A, R Ru/ A = 1.0 and 0.5, respectively. A non-stoichiometric solid solution range was identified in the Ca–Ru–O system at R Ru/Ca = 0.7–1.0. The relative densities of CaRuO 3, SrRuO 3, BaRuO 3 and Sr 2RuO 4 compacted by spark plasma sintering (SPS) were 82%, 95%, 97% and 96%, respectively. The electrical conductivity ( σ) of ARuO 3 showed a metallic behavior whereas Sr 2RuO 4 exhibited a semiconducting behavior. The σ increased in the order of Sr 2RuO 4, BaRuO 3, CaRuO 3 and SrRuO 3. The Seebeck coefficient ( S) of ARuO 3 was around 25–40 μV K −1 and almost independent of temperature whereas that of Sr 2RuO 4 decreased with increasing temperature. The thermal conductivity ( κ) of ARuO 3 slightly increased with increasing temperature, whereas that of Sr 2RuO 4 decreased with increasing temperature. SrRuO 3 showed much higher κ than the other compounds. The highest dimensionless figure of merit (ZT) values of ARuO 3 were around 0.02–0.025 at 1023 K whereas Sr 2RuO 4 was 0.001 at 600 K.

Relationship Among the Raoult Law, Zdanovskii−Stokes−Robinson Rule, and Two Extended Zdanovskii−Stokes−Robinson Rules of Wang

In this paper, the Raoult law (C. R. Acad. Sci. Ser. C 1887, 104, 1430), the Zdanovskii−Stokes−Robinson (ZSR) rule (Trudy Solyanoi Laboratorii Akad. Nauk SSSR 1936, No. 6, 5; J. Phys. Chem. 1966, 70, 2126), and two extended ZSR rules of Wang (Acta Metall. Sinica 1980, 16, 195; Ber. Bunsen-Ges. Phys. Chem. 1998, 102, 1045) are presented in a unified way. Similar to the Raoult law, which was first noted empirically in pyridine solutions, the ZSR rule for isopiestic mixed electrolyte and nonelectrolyte aqueous solutions can be extended to every kind of liquid and solid solutions such as organic mixtures, aqueous and nonaqueous electrolyte and nonelectrolyte solutions, liquid and solid alloys, molten salt mixtures, slags, and nonstoichiometric solid solutions, resulting in two extended ZSR rules of Wang. Although the solutions obeying the Raoult law (or the related classically ideal solution model) are very few as compared with the classically nonideal solutions, one classically ideal solution {B+C+...+Z} may...