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The Al–Cr–Dy system has been investigated over the whole composition by powder X-ray diffraction (PXRD), differential scanning calorimetry (DSC), scanning electron microscope and energy dispersion spectroscopy (SEM-EDS). The existence of known compounds Al8Cr4Dy and Al43Cr4Dy6 has been confirmed at 773 K. Binary compounds Al11Cr2 and Al17Dy2 do not exist in this isothermal section. The structure of the CeCr2Al20-type ternary compound Al20Cr2Dy has been determined with Rietveld refinement. This compound belongs to space group Fd 3 ¯ m and lattice parameter a = 1.44524 nm. The results shows that there are 16 single-phase regions, 31 two-phase regions and 16 three-phase regions in the studied isothermal section. The maximum solubility of Cr in AlDy2 and Al2Dy are confirmed to be 1.8 and 2.1 at. %, respectively. No significant solid solubility can be found in the other binary compounds of the Al–Cr–Dy ternary system at 773 K.

NaCeF4(s) is the single ternary compound in NaF-CeF3 system and it was prepared in solid state route. The characterization of NaCeF4(s) has been checked with X-ray diffraction technique and the purity has been checked with Rietveld analysis. The micro homogeneity and surface morphology of the prepared compound has been tested with EDS and SEM technique, respectively. The heat capacity, C0p[NaCeF4(s)] has been measured experimentally with DSC and the Gibbs energy of formation, ΔfG0m of NaCeF4(s) has been determined using Solid Electrolyte Galvanic Cell with CaF2(s) as solid electrolyte. The binary phase diagram of NaF(s)-CeF3(s) system has been calculated based on experimental thermodynamic data,. To study the stability domain and coexisting phases of NaCeF4(s) in reactor operating condition, the chemical potential diagram of Na-Ce-F-O system and ternary phase diagram of Na-Ce-F2 system has been calculated.

Using a high-temperature ampoule technique, a series of mixed nickel-iron-gallium metal-rich tellurides with layered structures, Ni3-xFexGaTe2, were prepared and characterized based on X-ray powder diffraction, energy-dispersive spectroscopy, and 57Fe Mossbauer spectroscopy data. These compounds may be regarded as a result of partial substitution of nickel by iron in the recently reported ternary Ni3-xGaTe2 series, which are based on NiAs/Ni2In type of structure. The compositional boundary for the substitution was found to be at x~1. According to the Mossbauer spectroscopy data, the substitution is not statistical, and iron atoms with the increase in x tend to preferentially occupy those nickel positions that are partially vacant in the initial ternary compound. Magnetic measurements data for the Ni3-xFexGaTe2 series show dramatic change in behavior from temperature-independent paramagnetic properties of the initial matrix to a low-temperature (~75 K) ferromagnetic ordering in the Ni2FeGaTe2.

The Zr–Cr–Si ternary system has been investigated over the whole composition by powder X-ray diffraction (PXRD) and scanning electron microscope equipped with energy dispersion spectroscopy (SEM-EDS). The ternary compound Zr4Cr4Si7 has been confirmed to exist in this system and its crystal structure data was acquired by Rietveld method. Rietveld refinement confirms that this ternary phase belongs to the Zr4Fe4Si7-type structure with space group I4/mmm (no.139) and lattice parameter a ​= ​1.3199(6) nm and c ​= ​0.5182(5) nm. The existence of ternary compounds i.e. ZrCrSi2, Zr2Cr4Si5, ZrCrSi and Zr2Cr3Si has also been confirmed at 973 ​K. The solid solubility of Cr in Zr–Si binary compounds and that of Si in α-ZrCr2 and Cr are determined to be between 1.5 ​at. % and 6.8 ​at. %. No remarkable solubility is determined in the other compounds. The results show that there are 19 single-phase regions, 40 two-phase regions and 22 three-phase regions in the studied isothermal section.

The Co–Sn–Ti system was studied in the crystallization interval (below ~50 at% Sn) by the methods of Scanning Electron Microscopy, microprobe analysis, Differential Thermal Analysis, X-ray diffraction. The liquidus and solidus projections and the melting diagram were constructed. Only Co 2 TiSn(τ1) ternary compound (Heusler phase-L1 2 ) was found in equilibria with the liquid in the concentration interval studied. Taking into account our recent data, the liquidus projection is characterized by the fields of primary crystallization of (βTi), (Co), binary-based phases Ti 3 Sn, Ti 2 Sn, Ti 5 Sn 3 , Ti 6 Sn 5 , Ti 2 Co, TiCo, TiCo 2 (c), TiCo 2 (h), TiCo 3 , βCo 3 Sn 2 , CoSn and ternary τ1. The solidus projection is characterized by thirteen three-phase fields, which result from invariant four-phase equilibria, five are of eutectic type (E) and eight of transition type (U) and the existence of one more region Ti 2 Sn 3 +βCoSn 3 +(Sn) in the solidus projection is discussed.

The crystal structures of two new compounds were determined from single-crystal X-ray diffraction measurements: Ni3+xSn4Zn, (x~1.35, a=7.110(2) A, b=4.123(1) A, c=10.346(3) A, β=90.23(2)°, space group I2/m, Z=2. R1=0.025, wR2=0.059 for 748 unique reflections, 35 variable parameters) and Ni6+xSn8Zn, x~1.35 (a=12.379(3) A, b=4.095(1) A, c=12.155(3) A, β=116.25(3)°, space group C2/m, Z=2. R1=0.026, wR2=0.052 for 1346 unique reflections, 60 variable parameters). In addition, a structural refinement was performed for Ni3+xSn4, x~0.13 (a=12.264(3) A, b=4.066(1) A, c=5.223(2) A, β=104.85(3)°, space group C2/m, Z=2. R1=0.019, wR2=0.046 for 617 unique reflections, 29 variable parameters). The three compounds show pronounced similarities among each other as well as to the crystal structures of surrounding binary Ni–Sn and ternary Ni–Sn–Zn compounds. In particular, the two new compounds form a homologous series with Ni3+xSn4, x~0.13. They contain “Ni4Sn4” and “Ni2Sn4” building blocks which by different interconnection build up the distinct structures. Topological relations with NiSn and Ni5−δSn4Zn, δ~0.25 are evident.

We perform first-principles density functional calculations on the yet unknown ternary compound lanthanum uranium trinitride LaUN3. Therefore, we evaluate the physical properties of the basic binary compounds LaN and UN2 such as total energies, elastic constants and band structures. These results were compared to those of the predicted structure of LaUN3. We used the USPEX code in order to find the structure of LaUN3 with the lowest total energy. We furthermore discuss the structure and the properties of LaUN3 and predict its thermodynamic stability.

A new intermetallic ternary compound La6Pd2.28Sb15 was synthesized from the reaction of lanthanum and palladium metals in a molten antimony flux. The compound crystallizes in the orthorhombic space group Immm with a ​= ​4.3082(9) A, b ​= ​15.399(3) A and c ​= ​19.689(4) A. The crystal structure contains a three-dimensional framework of Sb squares and ribbons that extend along the a axis, including complex Sb–Sb bonding. La6Pd2.28Sb15 is diamagnetic, with a magnetic susceptibility weakly dependent on temperature (T). The resistivity (ρ) decreases when lowering the temperature, indicating metallic behavior, and at low temperatures ρ depends quadratically on T. Interestingly, both the Hall resistivity and magnetoresistance present a nonlinear dependence on the applied magnetic field, suggesting a multiband behavior. This is supported by density-functional electronic structure calculations which show a complex Fermi surface originated in the antimonide substructures and containing both electron and hole pockets as well as open sheets.

The new ternary compound Al 15 Ge 4 Ni 3 ( τ 2 in the system Al–Ge–Ni) was synthesized in single crystalline form by a special annealing procedure from samples located in the three phase fields [L+Al+ τ 2 ] and [L+Ge+ τ 2 ]. The crystal structure of Al 15 Ge 4 Ni 3 was determined by single-crystal X-ray diffraction. The compound crystallizes in a new structure type in space group I 43 m , Pearson Symbol cI 88, cubic lattice parameter a =11.405(1) A. Phase diagram investigations indicate stoichiometric composition without considerable homogeneity range; τ 2 melts peritectically at T =444 °C. The crystal structure of Al 15 Ge 4 Ni 3 shows a unique combination of simple Cu 3 Au- and CaF 2 -type building blocks: a three dimensional network of CaF 2 -type units, formed by Ni and Al atoms, is interspaced by clusters (Al 6 Ge 8 ) resembling unit cells of the Cu 3 Au-type. Both structural motifs are connected by Al–Ge bonds. The ground state energy of the compound was obtained by DFT calculations and the densities of states were analyzed in detail. In addition, electron density maps were calculated in four different sections through the unit cell using the full potential linearized augmented plane-wave (FLAPW) method. The bonding situation in Al 15 Ge 4 Ni 3 was discussed combining results from electronic calculations with the analysis of the coordination of atoms.

Mg(MgxZn1-x)2P2 was found to be a key material in Zn3P2-based solar cells, which have attracted attention as an earth-abundant photovoltaic technology. However, Mg(MgxZn1-x)2P2 has not been investigated as a functional material thus far, and even the single-phase range in the Mg–P–Zn equilibrium phase diagram is currently unknown. Thus, in this work, we investigate the phase equilibria around Mg(MgxZn1-x)2P2 in the Mg–P–Zn system using Sn as a flux for equilibrium experiments. We find that Mg(MgxZn1-x)2P2 exists as a single phase with a trigonal P 3 ‾ m 1 structure from x = 0 to x = 0.55 based on our XRD and the SEM-EDS analyses. The lattice parameters, a and c, monotonically increase with increase in the Mg content. In addition, the Mg(MgxZn1-x)2P2 phase can equilibrate with Zn3P2 only in the case of x = 0 (MgZn2P2) despite the wide composition range available. The lattice mismatch between MgZn2P2 and Zn3P2 is about 0.5%, which is consistent with our previous results of an electron diffraction study on Mg(MgxZn1-x)2P2/Zn3P2 interfaces. We also find that the interface between Mg and Mg(MgxZn1-x)2P2 is unstable and that the interface reaction is expected to result in the formation of the Mg-rich phosphide phase, which is air- and water-sensitive. The instability of the reaction product in the atmosphere can degrade the device via the formation of voids around the interface, which was observed in our previous work. Therefore, we deduce that Mg is not suitable as the surface electrode of Mg(MgxZn1-x)2P2/Zn3P2 solar cells. The phase equilibria established in this study can aid in redesigning the device structure of Zn3P2-based solar cells and in further investigation of the physical properties of Mg(MgxZn1-x)2P2.

The Zintl compound CaAl2Si2 is peritectically decomposed to a mixture of Ca2Al3Si4 and aluminum metal at temperatures above 600 °C under a pressure of 5 GPa. The new ternary compound Ca2Al3Sl4 crystalizes with the space group Cmc21 and the lattice parameters a=5.8846(8), b=14.973(1), and c=7.7966(5) A. The structure is composed of aluminum silicide framework [Al3Si4] and layer structured [Ca2] network interpenetrating with each other. The electron probe microanalysis (EPMA) shows the formation of solid solutions Ca2Al3−xSi4+x (x

Phase relations have been established by electron probe microanalysis (EPMA) and X-ray powder diffraction (XPD) for the Sr-poor part of the ternary systems Sr–Zn–Si at 800 °C and Sr–Zn–Ge at 700 °C. In the Sr–Zn–Si system one new ternary compound SrZn 2+ x Si 2− x (0≤ x ≤0.45) with CeAl 2 Ga 2 structure and a statistical mixture of Zn/Si in the 4 e site was found. Neither a type-I nor a type-IX clathrate phase was encountered. This system is characterized by formation of two further phases, i.e. SrZn 1− x Si 1+ x with ZrBeSi-type (0.16≤ x ≤0.22) and SrZn 1− x Si 1+ x with AlB 2 -type (0.35≤ x ≤0.65) with a random distribution of Zn/Si atoms in the 2 c site. For the Sr–Zn–Ge system, the homogeneity regions of the isotypic phases SrZn 1− x Ge 1+ x with ZrBeSi-type (0≤ x ≤0.17) and AlB 2 -type (0.32≤ x ≤0.56), respectively, have been determined. Whereas the germanide SrZn 2+ x Ge 2− x (CeAl 2 Ga 2 -type) is characterized by a homogeneity region (0≤ x ≤0.5), the clathrate type-I phase Sr 8 Zn 8 Ge 38 shows a point composition.

From literature data presently available, the decomposition temperature and the nature of the decomposition reaction of the ternary compound {alpha}-AlFeSi (also designated as {alpha}{sub H} or {tau}{sub 5}) are not clearly identified. Moreover, some uncertainties remain concerning its crystal structure. The crystallographic structure and thermochemical behaviour of the ternary compound {alpha}-AlFeSi were meticulously studied. The crystal structure of {alpha}-AlFeSi was examined at room temperature from X-ray single crystal intensity data. It presents hexagonal symmetry, space group P6{sub 3}/mmc with unit cell parameters (293 K) a=12.345(2) A and c=26.210(3) A (V=3459 A{sup 3}). The average chemical formula obtained from refinement is Al{sub 7.1}Fe{sub 2}Si. From isothermal reaction-diffusion experiments and Differential Thermal Analysis, the title compound decomposes peritectically upon heating into {theta}-Fe{sub 4}Al{sub 13}(Si), {gamma}-Al{sub 3}FeSi and a ternary Al-rich liquid. Under atmospheric pressure, the temperature of this reversible transformation has been determined to be 772{+-}12 {sup o}C. -- Graphical abstract: Partial representation of the crystal structure of the {alpha}-Al{sub 7.1}Fe{sub 2}Si compound. Display Omitted Highlights: The main findings of our work are: {yields} a detailed X-rays crystal structure determination of the ternary compound {alpha}-AlFeSi. {yields} The precision of the silicon atoms positions in the crystal structure. {yields} A precised determination ofmore » the decomposition temperature of this compound.« less

Phase equilibria and crystal structures of ternary compounds were determined in the systems Ce–Pd–B and Yb–Pd–B at 850 °C in the concentration ranges up to 45 and 33 at% of Ce and Yb, respectively, employing X-ray single crystal and powder diffraction. Phase relations in the Ce–Pd–B system at 850 °C are governed by formation of extended homogeneity fields, τ2-CePd8B2−x (0.10 The Yb–Pd–B system is characterized by one ternary compound, τ1-Yb2Pd14B5, forming equilibria with extended solution YbPd3Bx, YbB6, Pd5B2 and Pd3B. The crystal structures of both Yb2Pd14B5 and isotypic Lu2Pd14B5 were determined from X-ray Rietveld refinements and found to be closely related to the Y2Pd14B5-type (I41/amd). The crystal structure of binary Yb5Pd2−x (Mn5C2-type) was confirmed from X-ray single crystal data and a slight defect on the Pd site (x=0.06) was established. The three structures τ1-Ce6Pd47−xB6, τ2-CePd8B2−x and τ3-Ce3Pd25−xB8−y are related and can be considered as the packings of fragments observed in Nd2Fe14B structure with different stacking of common structural blocks. Physical properties for Yb2Pd13.6B5 (temperature dependent specific heat, electrical resistivity and magnetization) yielded a predominantly Yb-4f13 electronic configuration, presumably related with a magnetic instability below 2 K. Kondo interaction and crystalline electric field effects control the paramagnetic temperature domain.

The subsolidus phase relations of the ternary system CuO-TiO{sub 2}-CaO sintered at 950 deg. C in air have been determined by powder X-ray diffraction method. Only one ternary compound CaCu{sub 3}Ti{sub 4}O{sub 12} was found in this system. From room-temperature dielectric property mapping at 10 kHz, a giant dielectric constant (epsilon{sub r}>10{sup 4}) was observed for most of the ceramic composites in the CuO-rich region and in the region along the CaO-CuO binary line. The composites in the CaCu{sub 3}Ti{sub 4}O{sub 12}-rich region were found to give a comparable giant dielectric constant when sintered at 1050 deg. C. The particular microstructure of larger grains with predominant phase surrounded by smaller grains with the secondary phases was found in such composites with a high dielectric constant. The relations between structures and dielectric properties were investigated. An internal barrier layer capacitance effect is the most probable mechanism to explain this particular dielectric behavior. - Graphical Abstract: In the ternary system, CuO-TiO{sub 2}-CaO, a giant dielectric constant (epsilon{sub r}) above 10{sup 4} (red color) was observed in most of the composites sintered at only 950 deg. C in the CuO-rich region. Dashed lines show the phase boundaries.

Phase relations in the ternary system Ce–Pd–Si have been established for the isothermal section at 8001C based on X-ray powder diffraction and EMPA techniques on about 130 alloys, which were prepared by arc-melting under argon or powder reaction sintering. Eighteen ternary compounds have been observed to participate in the phase equilibria at 8001C. Atom order was determined by direct methods from X-ray single-crystal counter data for the crystal structures of t8—Ce3Pd4Si4 (U3Ni4Si4type, Immm; a ¼ 0.41618(1), b ¼ 0.42640(1), c ¼ 2.45744(7) nm), t16—Ce2Pd14Si (own structure type, P4/nmm; a ¼ 0.88832(2), c ¼ 0.69600(2) nm) and also for t18—CePd1� xSix (x ¼ 0.07; FeB-type, Pnma; a ¼ 0.74422(5), b ¼ 0.45548(3), c ¼ 0.58569(4) nm). Rietveld refinements established the atom arrangement in the structures of t5—Ce3PdSi3 (Ba3Al2Ge2-type, Immm; a ¼ 0.41207(1), b ¼ 0.43026(1), c ¼ 1.84069(4) nm) and t13—Ce3� xPd20+xSi6 (0rxr1, Co 20Al3B6-type, Fm3 ¯ m; a ¼ 1.21527(2) nm). The ternary compound Ce2Pd3Si3 (structure-type Ce2Rh1.35Ge4.65, Pmmn; a ¼ 0.42040(1), b ¼ 0.42247(1), c ¼ 1.72444(3) nm) was detected as a high-temperature compound, however, does not participate in the equilibria at 8001C. Phase equilibria in Ce–Pd–Si are characterized by the absence of cerium solubility in palladium silicides. Mutual solubility among cerium silicides and cerium–palladium compounds are significant whereby random substitution of the almost equally sized atom species palladium and silicon is reflected in extended homogeneous regions at constant Cecontent such as for t2—Ce(PdxSi1� x)2 (AlB2-derivative type), t6—Ce(PdxSi1� x)2 (ThSi2-type) and t7—CePd2� xSi2+x. The crystal structures of compounds t4—Ce� 8Pd� 46Si� 46, t12—Ce� 29Pd� 49Si� 22, t15—Ce� 22Pd� 67Si� 11, t17—Ce� 5Pd� 77Si� 18 and t18—CePd1� xSix (x� 0.1) are still unknown.

In the lithium–europium–graphite system, a novel ternary compound was synthesised by direct immersion of a pyrolytic graphite platelet in a molten lithium-based alloy with a well chosen Li/Eu ratio at 400 °C. The ternary compound exhibits poly-layered intercalated sheets mainly constituted of two europium planes. Its chemical formula can be written LixEuC4, since the amount of lithium is still not determined. The 151Eu Mossbauer spectra clearly indicate a +II valence for europium. The magnetic susceptibility and the magnetisation versus temperature reveal a complex behaviour which is qualitatively described thanks to structural hypothesis and analogies with the magnetic properties of the binary EuC6 compound. A first ferromagnetic transition occurring at 225 K is attributed to interactions between both intercalated europium planes. The lower temperature susceptibility behaviour can be interpreted by antiferromagnetic interactions between in-plane neighbours and ferromagnetic interactions along the c-axis.

A new ternary compound, U3Co2Ge7, has been synthesized from the corresponding elements by a high temperature reaction using molten tin flux. It crystallizes in the orthorhombic La3Co2Sn7-type (Pearson's symbol oC24, space group Cmmm, No. 65) with lattice parameters determined from single-crystal X-ray diffraction as follows: a=4.145(2) A; b=24.920(7); c=4.136(2) A, V=427.2(3) A3. Structure refinements confirm an ordered structure having two crystallographically inequivalent uranium atoms, occupying sites with dissimilar coordination. U3Co2Ge7 orders ferromagnetically below 40 K and undergoes a consecutive magnetic transition at 20 K. These results have been obtained from temperature- and field-dependent magnetization, resistivity and heat-capacity measurements. The estimated Sommerfeld coefficient γ=87 mJ/mol-U K2 suggests U3Co2Ge7 to be a moderately heavy-fermion material.

The first ternary hafniumborate {beta}-HfB{sub 2}O{sub 5} was synthesized under high-pressure and high-temperature conditions in a Walker-type multianvil apparatus at 7.5 GPa and 1100 deg. C. The monoclinic hafnium-diborate crystallizes with four formula units in the space group P2{sub 1}/c with lattice parameters a=438.48(9), b=690.60(2), c=897.60(2) pm, and {beta}=90.76(3){sup o}. Due to the fact that high-pressure conditions favour the fourfold-coordination of boron, a structure is observed, which is built up exclusively from layers of BO{sub 4} tetrahedra; between the layers, the hafnium ions are coordinated square-antiprismatically by eight oxygen atoms. A structural comparison of {beta}-HfB{sub 2}O{sub 5} with minerals of the gadolinite-homilite-hingganite-datolite family proved this compound to be the simplest structural variant in this structure type, known so far. Along with a structural discussion, temperature-programmed X-ray powder diffraction data are shown, demonstrating the metastable character of this compound. - Graphical abstract: Synthesis of {beta}-HfB{sub 2}O{sub 5} via the multianvil high-pressure/high-temperature technique, representing the first ternary compound in the borate system Hf-B-O.

The Li1.746Nd4.494FeO9.493 (LNF) ternary phase, located in the Li2O-rich part of the Li2O–Nd2O3–Fe2O3 system, crystallizes with a cubic unit cell of dimension a = 11.9763 ( 3 ) A and the space group Im 3 m . Refinement on F resulted in R = 1.9 % . The structure is comprised of a network of corners, edges and faces sharing the coordination polyhedra of neodymium. In between this skeleton the regular octahedra of oxygen-coordinated iron and trigonal prisms of lithium are located. The Mossbauer spectra revealed the presence of Fe3+, Fe4+ and Fe5+ ions distributed on two symmetry-independent lattice positions.

The ternary compound Ba 2 Cd 3 Bi 4 crystallizes in the C -centered orthorhombic space group Cmce (No. 64) with its own type (Pearson's symbol oC 36; a =7.019(3) A, b =17.389(7) A and c =9.246(3) A determined at –23 °C). Although the structure of this intermetallic compound with transition metal in d 10 configuration has already been established, details such as the rather unusual coordination of the Cd-atoms and the elongation in specific direction of their anisotropic displacement parameters had not been explained. These facts, along with the higher than 12% R -values from the original structure determination prompted the systematic structural studies by single-crystal X-ray diffraction at several different temperatures. The results from these studies confirm strong temperature dependence of the cadmiums’ anisotropic displacement parameters, concomitant rather large thermal expansion along the crystallographic b -axis. Electronic band structure calculations performed by the TB-LMTO-ASA method are also reported.

Porous ZnWO{sub 4} films have been fabricated on Indium-tin oxide (ITO) glass and its photoelectrochemical properties and high photocatalytic activities towards degradation of rhodamine B (RhB) has been investigated. Using amorphous heteronuclear complex as precursor and with the addition of polyethylene glycol (PEG, molecular weight=400), the porous ZnWO{sub 4} films have been achieved at the temperature of 500 deg. C via dip-coating method. It is composed of approximately 70 nm-sized particles and exhibits substantial porosity. The textures and porosity of ZnWO{sub 4} films are dependent on preparation factors, such as the ratio of precursor/PEG and the annealing conditions. The formation mechanism of porous ZnWO{sub 4} films was proposed. The porous ZnWO{sub 4} films exhibited high photocatalytic activities towards degrading RhB. The top of valence band and the bottom of the conduction band was estimated to be -0.56 and 3.45 eV (vs. saturated calomel electrode (SCE)), respectively. -- Graphical abstract: Current vs. potential curves for ZnWO{sub 4} film treated at various temperatures: ((a) photo 500 deg. C; (b) photo 550 deg. C; (c) photo TiO{sub 2}; (d) dark 500 deg. C; (e) dark 550 deg. C; (f) dark TiO{sub 2}) in (B) in 0.5 M Na{sub 2}SO{sub 4} solution pH 6.0,more » scan rate=10 mV s{sup -1}.« less

A new ternary compound, Ce 2 PdGa 10 , has been synthesized using Ga flux and characterized by single-crystal X-ray diffraction. Ce 2 PdGa 10 adopts a tetragonal structure in the I 4 / mmm space group and is isostructural to Ce 2 NiGa 10 . Lattice parameters are a = 4.3230 ( 3 ) A , c = 26.536 ( 3 ) A , V = 495.91 ( 7 ) A 3 , and Z = 2 . The compound is metallic (d ρ/ d T >0), with the resistance decreasing roughly linearly with temperature from 300 to 175 K. The magnetic susceptibility of Ce 2 PdGa 10 is consistent with local-moment paramagnetism and no long-range magnetic ordering occurs down to 2 K. A large positive magnetoresistance over 200% is observed at 2 K for fields of 9 T. In this paper, we present the structure and physical properties of Ce 2 PdGa 10 and compared them to CePdGa 6 .

The standard molar Gibbs energy of formations of BaFe 12 O 19 (s), BaFe 2 O 4 (s), Ba 2 Fe 2 O 5 (s), Ba 3 Fe 2 O 6 (s) and Ba 5 Fe 2 O 8 (s) have been determined using solid-state electrochemical technique employing CaF 2 (s) as an electrolyte. The reversible e.m.f. values have been measured in the temperature range from 970 to 1151 K. The oxygen chemical potential corresponding to three phase equilibria involving technologically important compound BaFe 12 O 19 (s) has been determined using solid-state electrochemical technique employing CSZ as an electrolyte from 1048 to 1221 K. The values of Δ f G m 0 ( T ) for the above ternary oxides are given by Δ f G m 0 ( BaFe 12 O 19 , s )/ kJ mol −1 (±0.6)=−5431.3+1.5317 (T/ K ) (970⩽T/ K ⩽1151) Δ f G m 0 ( BaFe 2 O 4 , s )/ kJ mol −1 (±1.3)=−1461.4+0.3745 (T/ K ) (970⩽T/ K ⩽1151) Δ f G m 0 ( Ba 2 Fe 2 O 5 , s )/ kJ mol −1 (±1.4)=−2038.3+0.4433 (T/ K ) (970⩽T/ K ⩽1149) Δ f G m 0 ( Ba 3 Fe 2 O 6 , s )/ kJ mol −1 (±1.5)=−2700.1+0.6090 (T/ K ) (969⩽T/ K ⩽1150) and Δ f G m 0 ( Ba 5 Fe 2 O 8 , s )/ kJ mol −1 (±1.6)=−3984.1+0.9300 (T/ K ) (973⩽T/ K ⩽1150) The uncertainty estimates for Δ f G m 0 includes the standard deviation in the e.m.f. and uncertainty in the data taken from the literature. An isothermal oxygen potential diagram for the system Ba–Fe–O was constructed at 1100 K based on the thermodynamic data obtained in this study.

Redox intercalation of NH 4 + into vanadyl phosphate dihydrate (VOPO 4 ·2H 2 O) leads to a two-phase (NH 4 ) x VOPO 4 ·H 2 O ( x =0.2−0.9) compound with interlayer distances of 6.7 and 6.4 A. Ammonium ions can be incorporated into the interlayer space of VOPO 4 also by an ion exchange, starting from alkali-metal redox-intercalated vanadyl phosphate Me x VOPO 4 · y H 2 O ( Me =Li, Na, K, Rb). Several phases are formed during the ion exchange, one of them with the interlayer distance corresponding to the original Me x VOPO 4 · y H 2 O phase, the second one corresponding to formed (NH 4 ) x VOPO 4 ·H 2 O. In addition, a third phase is formed by the ion exchange when Li 0.98 VOPO 4 ·1.98H 2 O or Rb 0.60 VOPO 4 ·1.3H 2 O are used as starting compounds. An opposite ion exchange of NH 4 + for Me + starting from (NH 4 ) x VOPO 4 ·H 2 O does not proceed.

Subsolidus phase equilibria of the BaO–Nd2O3–CuOx system at pO2=100 Pa (0.1% O2 volume fraction, 810°C) and at pO2=21 kPa (21% O2 volume fraction, 930°C) have been investigated by applying controlled-atmosphere methods to minimize the presence of carbonate and CO2 and H2O contamination. Under carbonate-free conditions, the BaO–Nd2O3–CuOx phase diagrams at pO2=100 Pa and at pO2=21 kPa are similar to one another except for differences in the extent of the solid solutions. Apart from the limiting binary phases, the ternary system consists of three solid solutions and one stoichiometric ternary compound. The first solid solution is the high Tc series, Ba2−xNd1+xCu3O6+z (0.3⩾x⩾0 at pO2=100 Pa; 0.95 ⩾ x⩾ 0 at pO2=21 kPa). At pO2=21 kPa, a compositionally dependent phase change was detected, from tetragonal ( 0.7 > x⩾0 ) to orthorhombic (0.95⩾x⩾0.7). The second solid solution series, the ‘brown-phase’ Ba1+xNd2−xCuOz, has a narrow homogeneity region (0.10>x⩾0 at pO2=100 Pa; 0.15>x⩾0 at pO2=21 kPa). In the high BaO part of the phase diagram, a third solid solution (Ba2−xNdx)CuO3+z (x=0 to ≈ 0.3 at pO2=100 Pa; x=0–0.45 at pO2=21 kPa) was confirmed, as well as a nominally stoichiometric phase, Ba4Nd2Cu2Oz. The latter phase is an insulator, with a structure comprised of unusual CuO5 linear chains. A significant difference in tie line distribution involving the Ba2−xNd1+xCu3O6+z superconductor was found under carbonate-free conditions relative to literature studies completed in air. Instead of the BaCuO2+x–Ba2+xNd4−xCu2Oz tie line normally encountered in air, a Ba2−xNd1+xCu3O6+z–(Ba,Nd)2CuO3+x tie line was established. This tie line substantially expands the field of stability of the Ba2−xNd1+xCu3O6+z superconductor phase into the BaO-rich region of the phase diagram. Implications for the processing of materials based on the Ba2−xNd1+xCu3O6+z superconductor are discussed.

The subsolidus phase relations of R2O3-CaO-CuO ternary systems (R = Nd, Sm, Gd, Tm) have been investigated by X-ray powder diffraction. All samples were synthesized at about 950degrees in air. There exists a ternary compound Ca14-xRxCu24O41 (x = 4 for R = Nd, Gd and x = 5 for R = Sm) and a ternary solid solution Ca2+xR2-xCu5O10 (R = Nd, Sm, Gd, Tm) with a wide composition range Deltax of about 0.6. The compound Ca14-xRxCu24O41 possesses a layered orthorhombic structure and is isostructural to Sr14-xCaxCu24O41. The lattice parameters a and c of the compound are basically independent of the ionic radius of R, while the lattice parameter b and unit-cell volume V decrease substantially with the decrease of the ionic radii of R. The Ca2+xR2-xCu5O10 solid solution is isostructural to Ca2+xY2-xCu5O10, the structure of which is based on an orthorhombic "NaCuO2-type" subcell containing infinite one-dimensional chains of edge-shared square planar cuprate groups crosslinked by the layered cations Ca and R that locate in the inter-chain tunnels. (C) 2002 Elsevier Science (USA). All rights reserved.

The phase relationship of the La 2 O 3 –CaO–Ga 2 O 3 system at 1150°C has been studied and is expressed in a phase-diagram, in which the presence of two ternary compounds were confirmed. The ternary compound LaCaGaO 4 has two forms, i.e., the orthorhombic (o-) phase and the tetragonal (t-) phase. Both phases are isolators exhibiting ferroelectric behavior, so the structures were reformulated in the polar space groups.

Kinetics and formation mechanism of undoped and Al-doped LiNiO2 from Li2CO3 and NiO were investigated in this study. Without the addition of Al ions, sluggish kinetics for the formation of undoped LiNiO2 was observed. The fraction of undoped LiNiO2 reached 50% after Li2CO3 and NiO reacted at 700°C for 150 min. With the addition of 25% of Al ion, the fraction of Al-doped LiNiO2 reached 50% within 60 min at 700°C. The analysis of kinetics study indicates that the formation of undoped and Al-doped LiNiO2 is a diffusion-controlled process. Furthermore, the rate constant determined from Jander model {[1−(1−α)1/3]2=Kt} was significantly enhanced by the addition of Al. The activation energy for the formation of LiNiO2 drastically decreased from 190 kJ/mole (undoped reaction) to 83 kJ/mole when 25% Al was added. The enhancement of LiNiO2 formation by Al doping is attributed to the structure resemblance between αLiAlO2 and LiNiO2. αLiAlO2 acts as the seeding material which provides nucleation sites for the growth of LiNiO2.

The new ternary compound Pd 13 In 5.25 Sb 3.75 was found. Its crystal structure was determined using a CCD diffractometer at room temperature. Evaluations and refinements finally yielded a C-centered monoclinic structure (space group, C 2/ c ; Pearson symbol, mC 88, Z =4) with a =15.189(2) A, b =8.799(1) A, c =13.602(2) A, and β =123.83(1)°. For the entire data set of 3706 independent reflections residual values are R =0.0461 and R w =0.0789. The structure was found to be isotypic to Pd 13 Pb 9 with In and Sb on the Pb sites. The existence of a further ternary compound, which was already described as Pd 3 In 4 Sb 2 , could be confirmed. Its composition range was determined by EPMA to be PdIn 1.2–1.3 Sb 0.8–0.7 . It does not melt congruently and we were not able to find suitable single crystals. However, we were able to prepare the pure ternary compound in order to perform X-ray powder diffraction using a Guinier image plate technique. The entire diffraction spectrum was refined by full profile Rietveld method using the program Fullprof. The α -PdSn 2 structure type (space group, I 4 1 / acd ; Pearson symbol, t 148, Z =16), proposed for this compound, was confirmed and the lattice parameters are a =6.4350(1) A and c =24.3638(3) A. The residual values were R p =5.34 and R wp =6.70. The tetragonal PdSn 2 structure type is a mixed variant of the CaF 2 type and the CuAl 2 type structure. Also in this ternary compound we assumed a random contribution of In and Sb over the 16 e and 16 f positions. The electronic structures of both compounds were investigated by extended Huckel calculations. Crystal orbital overlap populations show extended bonding interactions between the main group elements. The bonding interactions of the main group elements are almost optimized at the experimentally observed In/Sb ratio of the ternary compound. The In/Sb ratio in Pd 13 In 5.25 Sb 3.75 can thus be rationalized on the basis of the electronic structure.

The chemical stability of the layered Li 1− x CoO 2 and Li 1− x Ni 0.85 Co O.15 O 2 cathodes is compared by monitoring the oxygen content with lithium content (1− x ) in chemically delithiated samples. The Li 1− x CoO 2 system tends to lose oxygen from the lattice at deep lithium extraction while the Li 1− x Ni 0.85 Co 0.15 O 2 system does not lose oxygen at least for (1− x )>0.3. This difference seems to result in a lower reversible (practical) capacity (140 mA h/g) for LiCoO 2 compared to that for LiNi 0.85 Co 0.15 O 2 (180 Ma h/g). The loss of significant amount of oxygen leads to a sliding of oxide layers and the formation of a major P3 and a minor O1 phase for the end member CoO 2− δ with δ =0.33. In contrast, Ni 0.85 Co 0.15 O 2− δ with a small amount of δ =0.1 maintains the initial O3 layer structure.

Superfine Li1−xMn2O4−σ powders were successfully synthesized by the alcohol–thermal method using 0.01 mol of MnO2, 0.01mol of LiOH·H2O, and 0.06mol of NaOH as starting materials at 160–200°C. The products are characterized by XRD, TEM, ED, BET, and ICP. Results show that the Li0.74Mn2O3.74 powder prepared at 200°C has an average size of 180 nm with BET surface areas of 16.44 m2/g. A possible formation mechanism is proposed. It was concluded that the alcohol acts not only as the solvent but also as the reducing agent in the synthesis of Li1−xMn2O4−σ powders. The effects of reaction temperature and the contents of NaOH and LiOH on the formation of single phase Li1−xMn2O4−σ were investigated.

The new ternary compound Th3Co3Sb4 was synthesized by arc melting. The compound crystallizes in the cubic space group I-43d (No. 220) with a=9.572(2) A and adopts the Y3Au3Sb4 structure, which is a filled version of the Th3P4 structure type. The crystal structure was solved and refined with single-crystal X-ray diffraction. Final R1/Rw2=1.52/3.73%. Th3Co3Sb4 is a metallic ferromagnet at room temperature. Electrical conductivity and thermoelectric power measurements show metallic behavior, which is also predicted by the electronic band structure calculations.

In this investigation, Bi 2 Ru 2 O 7 pyrochlore-type oxide was prepared using the Pechini process. We employed a sol–gel route, in which a solution of Ru(III) and Bi(III) in a mixture of citric acid and ethylene glycol was heated to form a polymeric precursor, followed by an annealing at higher temperatures during various periods. The oxide obtained was identified by X-ray diffraction analysis. The results revealed that the formation of homogeneous oxide with a single pyrochlore structure phase occured at or above 650°C. Sample powders consisted of fine grains with homogeneous morphology and an average size of about 0.5 μm. This new preparation procedure yielded an electrode material with improved electrochemical activity compared to those elaborated through conventional methods.

Mechanical activation (MA) of the LiOH+V2O5 and Li2CO3+V2O5 mixtures followed by brief heating at 673 K was used to prepare dispersed Li1+xV3O8. It was shown that structural transformations during MA are accompanied by reduction processes. EPR spectra of Li1+xV3O8 are attributed to vanadyl VO2+ ions with weak exchange interaction. The interaction of localized electrons (V4+ ions) with electron gas (delocalized electrons), which is exhibited through the dependence of EPR line width of vanadium ions versus measurement temperature (C–S–C relaxation), is revealed. It is shown that C–S–C relaxation is different for intermediate and final products. The properties of mechanochemically prepared Li1+xV3O8 are compared with those of HT-Li1+xV3O8, obtained by conventional solid state reaction. Mechanochemically prepared Li1+xV3O8 is characterized by a similar amount of vanadium ions, producing electron gas, but a higher specific surface area.

The first ternary compound in the Nb–Ni–Sb system, Nb28Ni33.5Sb12.5, has been synthesized and its structure has been determined by single-crystal X-ray diffraction methods. Nb28Ni33.5(2)Sb12.5(2) adopts the X-phase structure type (orthorhombic, space group Pnnm, Z=1, a=13.2334(5) A, b=16.5065(7) A, c=5.0337(2) A), which belongs to the set of tetrahedrally close-packed (TCP) structures adopted by many intermetallic compounds. Typical of such TCP structures, the atoms reside in sites of high coordination number, with Ni and Sb in CN12 and Nb in CN14, -15, and -16 sites. The relative importance of various metal–metal bonding interactions is discussed on the basis of extended Huckel band structure calculations. Nb28Ni33.5Sb12.5 displays metallic behavior with a room-temperature resistivity of 2.3×10−4 Ω cm.

Mechanochemical activation has been successfully used as an alternative method for producing Aurivillius oxides with n=1, like Bi2MoO6, Bi2VO5.5, and Bi2VO2. The analysis of the mechanoactivated materials by SEM and TEM allows the study of the mechanisms involved in the process of mechanical activation and the occurrence of mechanosynthesis. It is observed that if the amorphization of all the starting oxides is achieved during the process, evidence of mechanosynthesis, i.e., the synthesis of the final product, is found in the resulting particles. The phases obtained either cannot be synthezised by the traditional solid-state reactions or show special characteristics, all of which confirms that the mechanisms of phase formation involved in the mechanical and the thermal activations are different. Further annealing at higher temperatures makes all these structures go back to the phases traditionally obtained by thermal activation.

Oxygen transfer capacity (OTC) is needed, for example, in three-way catalysts (TWC) for treatment of exhaust gases, extraction of pure oxygen from gaseous mixtures such as air, or the extraction of hydrogen from hydrogen-containing compounds such as water or methane. This property is explored in fluorite-related materials of the formula Ce 1− x − y − z − p Pr x Tb y M z R p O 2− x ( x + y + z >0.5) in which M is a metal, especially Zr, Ti, V, Mo, W, Nb, Mn, Cu, Cr, Fe, Ni, Co, Ta, and Bi, and in which R is another rare-earth element. The OTC of these oxides is inherent in the characteristics of fluorite-related structures and the variable valency of Ce, Pr, and/or Tb. Such oxides can have the OTC property under reducing and oxidizing conditions without any reconstructive phase transitions. OTC data of some binary, ternary, and quaternary oxides containing Ce, Pr, or Tb are discussed.

MgIn 2 O 4 was prepared by the solid state reaction of MgO and In 2 O 3 . Microcrystals of MgIn 2 S 4 were formed on sintered MgIn 2 O 4 pellets by sulfurizing them in a H 2 S atmosphere. The bandgap of MgIn 2 S 4 was evaluated as 2.1 eV. A very high efficiency photocurrent was observed on MgIn 2 S 4 ∣MgIn 2 O 4 electrodes. Photocurrent generation of MgIn 2 S 4 ∣MgIn 2 O 4 electrodes was explained from the viewpoint of semiconductor sensitization. The flat band potential of MgIn 2 S 4 was evaluated as −1.0 V vs Ag∣AgCl in aqueous polysulfide redox electrolyte (1 M OH – , 1 M S 2− , 10 −2 M S).

We have studied the stability of Pr2NiO4+δ under pure oxygen flow by in situ measurement of its weight versus T. Above 850°C a fast oxidation is observed corresponding to the ex-solution of PrOy species and to the formation of metallic Pr4Ni3O10−x. This reaction is not reversible. The quantity of exchanged oxygen, its fast kinetics, and the metallic behavior of the composite suggest that this material should have interesting applications for electrodes of solid oxide fuel cells.

We report on the synthesis and general physical properties of polycrystalline samples of LnNiO3 (Ln=Pr, Nd, Sm). These compounds crystallize in a GdFeO3-type orthorhombically distorted perovskite structure, Pbnm space group symmetry, and reveal a first-order metal–insulator transition in a large range of temperatures varying from ∼130 to 400 K. The samples were prepared through three different methods: (1) the conventional ceramic process by mixing and reacting simple oxides; (2) through precipitation of hydroxides of Ln3+ and Ni3+ and (3) through sol–gel precursors. The samples were subjected to heat treatments at temperatures up to 1000°C and under oxygen pressures as high as 70 bar. Observations of the microstructure and measurements of X-ray powder diffraction XRD, electrical resistivity ρ(T), and differential scanning calorimetric DSC, indicated important effects that precursors from different methods have upon the final properties of these compounds. A comparison between these characterizations revealed that sol–gel precursors resulted in better quality samples of LnNiO3 compounds.

The isothermal section of the phase diagram for the system Ca-Rh-O at 1273 K has been determined by equilibrating 12 compositions in the ternary and identifying phases present in quenched samples by optical microscopy, powder X-ray diffraction(XRD), and energy-dispersive analysis of X rays (EDX). One ternary compound, $CaRh_2O_4$, was found to be stable. It coexists with CaO and metallic Rh. All the alloy compositions are in equilibrium with CaO. The standard Gibbs energy of formation of $CaRh_2O_4$ and the oxygen chemical potential corresponding to the three-phase field Rh+CaO+$CaRh_2O_4$ were determined using novel designs of solid state cells incorporating yttria-stabilized zirconia as the electrolyte: Pt-Rh, CaO+$CaRh_2O_4$ Rh/$(Y_2O_3)$$ZrO_2$/Rh+$Rh_2O_3$, Pt-Rh, Pt+Rh, CaO+$CaRh_2O_4$+Rh/$(Y_2O_3)$$ZrO_2$/$O_2$(0.1 MPa),Pt-Rh. Buffer electrodes were introduced between reference and working electrodes to dissipate the electrochemical flux of oxygen through the solid electrolyte caused by the difference in chemical potential of oxygen at the electrodes. Polarization of the electrodes was prevented by the use of buffer electrodes. For the reaction $2Rh+CaO+\frac{2}{3}O_2 \rightarrow CaRh_2O_4$, $\Delta G^o=\frac{2}{3} \Delta \mu_{02}$ =-493,340+288.67T $(\pm 285)$ J/mol. The Gibbs energy of formation of the interoxide compound from the component binary oxides is $\beta-Rh_2O_3+CaO$ $\rightarrow CaRh_2O_4$, $\Delta G^o=-101,670+10.6T (\pm 290) J/mol$. Using the Neumann-Kopp rule to estimate the heat capacity of $CaRh_2O_4$, the standard enthalpy of formation and standard entropy of the compound at 298.15 K are evaluated as -1142.3$(\pm 2)$ kJ/mol and 103.2$(\pm 2)$ J/mol'K, respectively.

The new ternary compound Ba 2 CdTe 3 has been prepared by the reaction of a stoichiometric mixture of elements at 700°C. Its structure was determined via the Rietveld refinement method using powder X-ray diffraction with R p / R wp (%)=6.54/8.67. Ba 2 CdTe 3 crystallizes in space group Pnma (No. 62) of the orthorhombic system with Z =4 and a =9.8198(2) A, b =4.7436(1) A, c =19.0638(5) A. It is isotypic to Ba 2 MnS 3 and K 2 AgI 3 . The structure consists of one-dimensional chains of 1 ∞ [CdTe 2/2 Te 2 ] 4− separated by Ba 2+ cations. The chain is made of corner-sharing CdTe 4 tetrahedra. Each Ba atom is coordinated to seven tellurium atoms to form a trigonal prism with one rectangular face capped by a Te atom.

In this paper, we present a comparative electrochemical study of copper insertion into series of Mo 6 Se 8− x S x phases which are obtained through different synthesis processes. We show that α -, β -, and HT-forms can reversibly accommodate copper at room temperature. The variation of the integral copper insertion rate is a function of the sulfur content and the synthesis type of pseudobinaries. While the mechanism of copper intercalation is quite similar for the different Mo 6 Se 8− x S x for a given x , there is a drastic difference for α - and β -Mo 6 S 8 compound. This behavior is explained on the basis of structural considerations. If the extra Mo atoms, present in the lattice channels of the β form and HT-Mo 6 Se 8− x S x , are not displaced by this copper intercalation, they are shown to be mobile through cationic exchange reactions and chemical deinsertion at higher temperature.

It has been established using X-ray photoelectron spectroscopy in combination with other physical methods that the initial stages of mechanochemical synthesis of LiMn 2 O 4 in mixtures of MnO 2 with LiOH and Li 2 CO 3 are considerably different. In the first case the “smearing” of LiOH, having a flaky structure, on the surface of MnO 2 and the formation of an amorphous layer take place. The reaction is accompanied by a redox process, with the participation of OH groups and Mn 4+ ions and with diffusion of lithium ions to the interior of the particles, and is completed by formation of Li–O–Mn bonds. No change in the valence state of manganese was detected, in Li 2 CO 3 , only brittle fracture was observed. Formation of defect spinel-like Li 2 O · y MnO 2 (2.5≤ y ≤4) on the surface is proposed.

For the first time, copper ampoules have been used as reactors for the solid-state synthesis of complex lanthanide fluorides under vacuum. The high ductility of copper allows for high-vacuum tight sealing of the ampoules by cold welding. Furthermore, no chemical reactivity of copper toward solid fluorides has been observed. Thus, for an examination in view of optical upconversion properties, the superstructure phases Ba4−xY3+xF17+x(x≈0.08) and Pb4∓xY3±xF17±x(x≤0.2) have been synthesized by annealing of mixtures of binary fluorides in evacuated copper ampoules.

Phase relations in the system La2O3–NiO–Li2O at 700, 800, and 900°C have been investigated by solid synthesis, X-ray diffraction analysis, and chemical analysis. Only the ternary compound La4NiLiO8was found in the system. X-ray diffraction data of La4NiLiO8are presented.