ChemInform Abstract: (Sr1-xBax)FeO2 (0.4 ≤ x ≤ 1): A New Oxygen-Deficient Perovskite Structure.

The new oxygen-deficient perovskites of title are prepared by reaction of (Sr_1-xBa_x)FeO_3-δ (x = 0.4, 0.5, 0.6, 0.7, 0.8, 0.9; δ ≤ 0.5; obtained from stoichiometric mixtures of SrCO₃, BaCO₃, and Fe₂O₃ at 1473 K in air for 48 h) with an excess of CaH₂ at 593 K for 3—14 d (0.4 ≤ x ≤ 0.9) and NaH at 413 K for 3 d (x = 1.0).     

Nitrido-Sodalithe. II. Synthese,Struktur und Eigenschaften von M(6+(y/2)–x)H2x[P12N24]Zy mit M = Fe,Co, Ni,Mn; Z = Cl,Br, I; 0 ≤ x ≤ 4; y ≤ 2

Nitrido-Sodalites. II. Synthesis, Crystal Structure, and Properties of M_{(6+(y/2)–x)}H_2x[P₁₂N₂₄]Z_y with M = Fe, Co, Ni, Mn; Z = Cl, Br, I; 0 ≤ x ≤ 4; y ≤ 2 The nitrido sodalites M_{(6+(y/2)–x)}H_2x[P₁₂N₂₄]Z_y with M = Fe, Co, Ni, Mn; Z = Cl, Br, I; 0 ≤ x ≤ 4; y ≤ 2 are obtained by the reaction of HPN₂ or [PN(NH₂)₂]₃ with the metal halogenide MZ₂ (T = 700°C). The compounds are isotypic to Zn_(7–x)H_2x[P₁₂N₂₄]Cl₂. An increase of the ionic radii of the cations or anions results in an expansion of the lattice which is caused by an increase of the P? N? P angle. The influence of the cation is more dominant than that of the anion. By reacting [PN(NH₂)₂]₃ with metal halogenide (MZ₂) hydrogen free, X-ray amorphous products are obtained. The formation of the chloride-containing P? N-sodalite in this reaction begins at temperatures below 450°C.     

Crystal structure and magnetism of the FexNi8-xSi3 materials, 0 ≤ x ≤ 8

The crystal structure and magnetic properties of the materials Fe_xNi_8-xSi₃ with 0 ≤ x ≤ 8 have been investigated to estimate any possible magnetocaloric effect and compare it to that in known magnetocalorics. Two structural ranges could be identified in this system by X-ray and neutron diffraction. The structure of the samples with 0 ≤ x ≤ 4 is related to the trigonal structure of Ni₃₁Si₁₂. Doubled c lattice parameters compared to the one in Ni₃₁Si₁₂ are observed in the samples with x = 2 and x = 3. The average structure of Fe₂Ni₆Si₃ has been determined by X-ray single-crystal diffraction. The compounds with the compositions 5 ≤ x ≤ 8 crystallize in cubic Fe₃Si-type structure. Magnetic measurements have shown that the compound Fe₃Ni₅Si₃ displays a phase transition close to room temperature. However, its magnetocaloric effect is much smaller than the one in the promising magnetocaloric materials.     

ChemInform Abstract: The Fluorite Related Modulated Structures of the Gd2(Zr2‐xCex)O7 Solid Solution: An Analogue for Pu Disposition.

The fluorite‐related structures of the Gd₂(Zr_2‐xCe_x)O₇ (0 ≤ x ≤ 2) solid solution, of interest as a model system for ceramic disposition of Pu (with Ce as a Pu surrogate), are determined by XRD, XANES, TEM, and EELS.     

ChemInform Abstract: Gold-Tin Ordering in SrAu2Sn2.

The solid solutions SrAu_xSn_4-x (1.7 ≤ x ≤ 2.2) are prepared by high-frequency melting of the elements (Nb ampules, 950—1150 K, 2—12 h).     

Preparation and electrical and magnetic properties of Sr2−xNaxCuO3 (0 ≤ x ≤ 1) solid solutions

Mixed-valence copper(II/III) oxide solid solutions Sr_2?xNa_xCuO₃ (0 ≤ x ≤ 1) have been prepared by solid-state reactions in oxygen atmosphere. All solid solutions exhibit the structure of Sr₂CuO₃ (S.G. Immm). Electrical conductivity and thermoelectric power measurements show a semiconducting behavior in the whole composition range. The electronic structure of Sr₂CuO₃ is compared with that of La₂CuO₄ on the basis of an iono-covalent model. Interpretation of transport properties suggests the formation of small polarons. Magnetic susceptibility and EPR measurements show that the antiferromagnetic ordering of Sr₂CuO₃ tends to vanish as x increases, however magnetic interactions are still strong for a concentration of Cu²⁺ ions corresponding to x = 0.8.     

Hydrothermal synthesis, structure and property of nano-BaTiO3-based dielectric materials

A series of Ba_1-xSr_xTi_1-yZr_yO₃ (0≤x≤0.5, 0≤y≤0.4) and BA_1?xZn_xTi_1?ySn_yO₃ (0≤x≤0.3, 0≤y≤0.3) solid solutions were synthesized by low-temperature/low-pressure hydrothermal method below 170°C, 0.8 MPa. XRD pattern and cell parameters-composition figures of these prepared powders demonstrated that they are completely miscible solid solutions based on BaTiO₃. Furthermore, TEM showed that they have a shape of uniform, substantially spherical particles with an average particle size of 70 nm in diameter. The sintered ceramics of those powders doped by Sr²⁺ and Zr⁴⁺ or Zn²⁺ and Sn⁴⁺ have dielectric constant twelve times higher than and dielectric loss 1/6 those of pure BaTiO₃ phase at room temperature.     

ChemInform Abstract: Mixed‐Valent Neptunium(IV/V) Compound with Cation—Cation‐Bound Six‐Membered Neptunyl Rings.

Na_xNp^IV(Np^VO₂)₆ (OH)_1+xCl₉(H₂O)_8‐x (0 < x ≤ 1) is synthesized by evaporation of a neptunium(V) acidic (HCl) stock solution over several months to complete dryness.     

Study of Sb‐doped SnO2 Gray Ceramic Pigment with Cassiterite Structure

In this study, Sb_xSn_1?xO₂ (0 ≤ x ≤ 0.5) compositions were synthesized by the ceramic method from Sb₂O₃‐SnO₂ and Sb₂O₅‐SnO₂ mixtures and characterized by Differential thermal analysis (DTA) and thermogravimetric analysis (TG), X‐ray diffraction, UV‐V‐NIR spectroscopy and CIE L*a*b* (Commission Internationale de l'Eclairage L*a*b*) parameters measurements. Solid solutions with cassiterite structure were obtained at 1300 °C. These solid solutions are stable into glazes. From Sb₂O₃, light gray coloured materials were obtained. From Sb₂O₅, bluish gray coloured materials were obtained at 1300 °C/6h when x ≥ 0.3. Sb_xSn_1?xO₂ with 0.3 ≤ x < 0.5, T = 1300 °C and Sb₂O₅ might be established as compositional range, fired temperature and antimony precursor to obtain gray ceramic pigments in this system.     

Verbindungen mit Schichtstrukturen in den Systemen CuGa5S8/CuIn5S8 und AgGa5S8/AgIn5S8

Compounds with Layered Structures in the Systems CuGa₅S₈/CuIn₅S₈ and AgGa₅S₈/AgIn₅S₈ The title systems have been investigated by single crystal and powder X‐ray diffraction methods on quenched samples. In the system AgGa_xIn_5–xS₈ spinel type phases are formed up to x < 2. A compound crystallising with a hexagonal layered structure is obtained for 2 < x ≤ 3. The crystal structure of this layered phase has been solved on a single crystal of composition AgGa₃In₂S₈: space group P6₃mc, Z = 2, a = 380.80 and c = 3076.4 pm. The structure is isotypic to the Zn₂In₂S₅ (II a) type. The sample AgGa₄InS₈ crystallises in a Wurtzite like structure with a = 377.25 and c = 616.1 pm. In the system CuGa_xIn_5–xS₈ a new compound with layered structure has been detected for 1 ≤ x ≤ 2 which crystallises hexagonally with a = 380.28 and c = 3073.4 pm (x = 2). For the spinel CuIn₅S₈ an exchange of In by Ga is not detected.     

Complex Phosphates in the Li(Na)3]PO4-InPO4 Systems

Subsolidus sections in the systems Li₃PO₄-InPO₄ (950°C) and Na₃PO₄-InPO₄ (800, 900, and 1000°C) have been studied by X-ray powder diffraction. The compound Li₃In(PO₄)₂ has been synthesized, and the nasicon-type solid solution Li_{3(1 ? x)}In_{2 + x}(PO₄)₃ (0.67 ≤ x ≤ 0.80). has been found to exist. In the system Na₃PO₄-InPO₄, the solid solution Na_{3(1 ? x)}In_x/3PO₄ (0 ≤ x ≤ 0.2) and two complex phosphates exist: Na₃In(PO₄)₂ and Na₃In₂(PO₄)₃. These complex phosphates are dimorphic, with the irreversible-transition temperature equal to 675 and 820°C, respectively. Na₃In(PO₄)₂ degrades at 920°C. Ionic conductivity has been measured in some phases in the system.     

Complex copper(II) fluorides. XV. The Ternary System BaF2?CuF2?ScF3

The liquid-solid phase diagram of the binary system BaF₂? ScF₃ is established by D.T.A. and radiocrystallography. Three fluorides are disclosed: Ba₃Sc₂F₁₂, Ba₅Sc₃F₁₉ and a cubic high temperature phase Ba_1?xSc_xF_2+x (x = 0.17), the structure of which derives from that of BaF₂. A solid solution between BaF₂ and ScF₃ is also evidenced at high temperature. The ternary system BaF₂? CuF₂? ScF₃ is investigated by radiocrystallography and an isothermal section at 670°C is given. It shows the existence of four phases: a complex quaternary fluoride Ba₁₀Cu₁₂ScF₄₇, two “polytypic” phases the structure of which derives from that of BaCuF₄ and a tetragonal solid solution Ba₅Sc_3?xCu_xF_19?x with 0 ≤ x ≤ 1.     

Synthesis and Characterization of Niobium Substituted Hexagonal Tungsten Bronzes

Alkali metal tungsten bronzes, M_xWO₃, and its niobium substituted forms, M_xNb_yW_1‐yO₃, have been prepared with M = K and Rb and nominal compositions of x = 0.20, 0.25, 0.30 and 0.0 ≤ y ≤ 0.20 at temperatures between 600 and 900?C. The X‐ray powder patterns reveal that single phases of niobium substituted hexagonal tungsten bronze (HTB) can be prepared for x = 0.2, y ≤ 0.05 ; x = 0.25, y ≤ 0.125 and x = 0.3, y ≤ 0.15. Investigations of the optical reflectivity and the infrared absorption of Rb_0.3Nb_yW_1‐yO₃ indicate a decreasing concentration of free carrier with increasing niobium content.     

Tantalum‐Niobium Mixing in Ta3–xNbxTeI7 (0 ≤ x ≤ 3)

A substitutional study of the layered, trinuclear metal cluster system, Ta_3–xNb_xTeI₇ (0 ≤ x ≤ 3), has been performed. Synthetic, crystallographic, and spectroscopic results are presented for starting compositions corresponding to the x values: 1, 1.5, and 2. For the entire composition range studied, Ta(Nb) could readily substitute into the Nb(Ta)₃TeI₇ structure, but with changes in the observed stacking arrangements of the layers as x varies. For tantalum‐rich (x ≤ 1.8) phases, the structure conformed to the Nb₃SeI₇ structure type, also adopted by Ta₃TeI₇ and one polytype of Nb₃TeI₇. Niobium‐rich (i. e. x ≥ 1.7) phases were observed to adopt two structure types according to X‐ray powder diffraction, but crystals could only be obtained for the Nb₃SBr₇ structure type, which is a second modification of Nb₃TeI₇. Extended Hückel calculations are used to discuss the distribution of metal clusters in this system.     

Neue Vertreter des Er6[Si11N20]O‐Strukturtyps Hochtemperatur‐Synthesen und Kristallstrukturen von Ln(6+x/3)[Si(11–y)AlyN(20+x–y)]O(1–x+y) mit Ln = Nd,Er, Yb,Dy und 0 ≤ x ≤ 3, 0 ≤ y ≤ 3

New Representatives of the Er₆[Si₁₁N₂₀]O Structure Type. High‐Temperature Synthesis and Single‐Crystal Structure Refinement of Ln_(6+x/3)[Si_(11–y)Al_yN_(20+x–y)]O_(1–x+y) with Ln = Nd, Er, Yb, Dy and 0 ≤ x ≤ 3, 0 ≤ y ≤ 3 According to the general formula Ln_(6+x/3)[Si_(11–y)Al_yN_(20+x–y)]O_(1–x+y) (0 ≤ x ≤ 3, 0 ≤ y ≤ 3) four nitridosilicates, namely Er₆[Si₁₁N₂₀]O, Yb_6.081[Si₁₁N_20.234]O_0.757, Dy_0.33Sm₆[Si₁₁N₂₀]N, and Nd₇[Si₈Al₃N₂₀]O were synthesized in a radiofrequency furnace at temperatures between 1300 and 1650 °C. The homeotypic crystal structures of all four compounds were determined by single‐crystal X‐ray diffraction. The nitridosilicates are trigonal with the following lattice constants: Er₆[Si₁₁N₂₀]O: a = 978.8(4) pm, c = 1058.8(3) pm; Yb_6.081[Si₁₁N_20.243]O_0.757: a = 974.9(1) pm, c = 1055.7(2) pm; Dy_0.33Sm₆[Si₁₁N₂₀]N: a = 989.8(1) pm, c = 1078.7(1) pm; Nd₇[Si₈Al₃N₂₀]O: a = 1004.25(9) pm, c = 1095.03(12) pm. The crystal structures were solved and refined in the space group P31c with Z = 2. The compounds contain three‐dimensional networks built up by corner sharing SiN₄ and AlN₄ tetrahedra, respectively. The Ln³⁺ and the “isolated” O^2– ions are situated in the voids of the structures. According to Ln_(6+x/3)[Si_(11–y)Al_yN_(20+x–y)]O_(1–x+y) an extension of the Er₆[Si₁₁N₂₀]O structure type has been found.     

Semiclathrates of the Ge-P-Te system: synthesis and crystal structures

Novel compounds [Ge_46?xP_x]Te_y (13.9≤x≤15.6, 5.92≤y≤7.75) with clathrate‐like structures have been prepared and structurally characterized. They crystallize in the space group Fm$\bar 3Novel compounds [Ge(46-x) P(x) ]Te(y) (13.9≤x≤15.6, 5.92≤y≤7.75) with clathrate-like structures have been prepared and structurally characterized. They crystallize in the space group Fm ?3 with the unit cell parameter changing from 20.544(2) to 20.698(2) ? (Z=8) on going from x=13.9 to x=15.6. Their crystal structure is composed of a covalently bonded Ge-P framework that hosts tellurium atoms in the guest positions and can be viewed as a peculiar variant of the type?I clathrate superstructure. In contrast to the conventional type I clathrates, [Ge(46-x) P(x) ]Te(y) contain tricoordinated (3b) atoms and no vacancies in the framework positions. As a consequence of the transformation of the framework, the majority of the guest tellurium atoms form a single covalent bond with the host framework and thus the title compounds are the first representative of semiclathrates with covalent bonding. A comparison is made with silicon clathrates and the evolution of the crystal structure upon changing the tellurium content is discussed.     

Preparation and Superconductivity of a Series of Bi2CaSr2-XBaxCu2O8+δ

By means of the addition of Ba into the Bi-Ca-Sr-Cu-O 2122 system, a series of Bi₂CaSr_2-xBa_xCu₂O_8+δ (0 ≤ × ≤ 2) quinary metal oxides were prepared by the citrate route and by the conventional powder reaction method. The samples prepared by the former method have better properties than the latter. It was found that 5 was not equal to zero for all of them and that it increased with decreasing Tc. Two phases were indentified in the oxides containing all five metal elements. One is the Bi-Ca-Sr-Cu-O 2122 phase, the other is a new insulating phase which probably contains Bi-Ca-Ba-Cu-O with undetermined stoichiometry. Superconductivity was found in those samples for which × ≤ 1.50 with their Tc onsets between 93–78 K by resistivity measurements. Superconductivity decreased monotonically with increasing x. However, residual resistance was found in those samples for which 1.00 ≤ × ≤ 1.50, The Meissner effect appears in the samples where × ≤ 1.00 with Tc onsets between 88–80 K. For x = 1.75 and 2.00, the samples were semiconductors with resistivities of 6.66 × 10² and 6.96 × 10³ Ω cm at 290 K, and activation energies of 0.109, and 0.298 eV, respectively.     

Homologous Silver Bismuth Chalcogenide Halides (N,x)P. III. The (4, x)P, (5, x)P,and (7, x)P Structure Families of Modular Compounds with Tunable Composition and Structure

The crystal structures of six members of the homologous series with general formula [BiQX]₂[Ag_xBi_1?xQ_2?2xX_2x?1]_N+1 (Q = S, Se; X = Cl, Br; 1/2 ≤ x ≤ 1) and N = 4, 5, or 7 were determined by single‐crystal X‐ray diffraction. The series are characterized by the parameters N and x and are denoted ^{(N, x)}P. Ag₃Bi₄S₆Cl₃ (x = 0.60) (I) , Ag_3.5Bi_3.5S₅Br₄ (x = 0.70) (II) and Ag_3.65Bi_3.35Se_4.70Br_4.30 (x = 0.73) (III) belong to ^{(4, x})P series Ag_5xBi_7?5xQ_12?10xX_10x?3 and adopt the AgBi₆S₉ structure type. The ^{(5, x)}P compound Ag_3.66Bi_4.34S_6.68Br_3.32 (IV) , which corresponds to x = 0.61 in Ag_6xBi_8?6xS_14?12xBr_12x?4, crystallizes isostructurally to AgBi₃S₅. The compounds Ag_4.56Bi_5.44Se_8.88Br_3.12 (x = 0.57) (V) and Ag_5.14Bi_4.86S_7.76Br_4.24 (x = 0.64) (VI) , which are members of ^{(7, x)}P series Ag_8xBi_10?8xQ_18?16xBr_16x?6, adopt the Ag₃Bi₇S₁₂ structure type. In the monoclinic crystal structures (space group C2/m) two kinds of layered modules alternate along [001]. Modules of type A uniformly consist of paired rods of face‐sharing monocapped trigonal prisms around Bi atoms with octahedra around mixed occupied metal positions (M = Ag/Bi) between them. Modules of type B are composed of [MZ₆] octahedra, which are arranged in NaCl‐type fragments of thickness N. All structures exhibit Ag/Bi disorder in octahedrally coordinated metal positions as well as Q/X mixed occupation of some anion positions. Corresponding to their black color, all compounds are narrow‐gap semiconductors (E_g = 0.35 eV for (II) ). General characteristics of the entire class of ^{(N, x)}P compounds are gathered in a catalogue.     

Präparative und röntgenographische Untersuchungen über das System Al2S3?ZnS (Temperaturbereich 800–1080°C)

Einkristalle von α-ZnAl₂S₄ mit Spinellstruktur (a = 10,009₃ Å) lassen sich durch chemische Transportreaktion bei 740°C erhalten. Beim Erhitzen der Verbindung auf 800–900°C tritt Zerfall in eine ZnS-arme defekte Spinellphase und in eine ZnS-reiche Phase mit defekter Wurtzitstruktur ein. Bei 830–860°C liegen die Grenzen des zweiphasigen Bereichs etwa bei Zn_0,98Al_2,01S₄ (kubische α-Phase, a = 10,007₂ Å (25°C)) und Zn_1,80Al_1,47S₄ (hexagonale Wurtzitphase, a = 3,76₀, c = 6,1₅ Å (25°C)). Mischungen von ZnS, Al und S entsprechend der Zusammensetzung Zn_xAl_8/3?2x/3S₄ mit 0,33 ≤ x ≤ 0,98, die auf 830–860°C (70–140 h) erhitzt worden sind, liefern nach Abkühlung auf Raumtemperatur homogene Produkte mit defekter Spinellstruktur. Die bei der Zusammensetzung Al₂S₃ · ZnS beobachtete Mischungslücke setzt sich bei höherer Temperatur unter Verschiebung der Phasengrenzen und Ausbildung von Hochtemperatur-Phasen fort. Eine Hochtemperaturmodifikation des ZnAl₂S₄ existiert bis 1080°C nicht. Mischungen von ZnS, Al und S mit 0,44 ≤ x ≤ 0,85, die auf 1060–1080°C (72–96 h) erhitzt worden sind, zeigen nach Abkühlung auf Raumtemperatur eine bisher nicht beschriebene rhomboedrische Hochtemperaturphase (γ-Phase), deren Struktur als eine Defektstruktur des ZnIn₂S₄-Typs aufgefaßt werden kann. Bei x = 1,00 erhält man nach thermischer Behandlung bei 1060–1080°C ein zweiphasiges Produkt, das neben der γ-Phase eine orthorhombische Phase (β-Phase, Überstruktur des Wurtzit-Typs) enthält. Die β-Phase tritt als einzige Phase auf, wenn für die Ausgangsmischung gilt: 1,40 ≤ x ≤ 1,70. Die Löslichkeit von Al₂S₃ in ZnS (Wurtzit) unter Bildung einer statistischen Defektstruktur des Wurtzit-Typs reicht bei 1060–1080°C bis Zn_1,70?1,80Al_1,53?1,47S₄(Al₂S₃ · (2,2-2,5) ZnS). Preparative and X-Ray Investigations on the System Al₂S₃? ZnS (Temperature Region 800–1080°C) Single crystals of α-ZnAl₂S₄ with spinel structure (a = 10.009₃ Å) have been obtained by chemical transport reaction at 740°C. Heating of the compound to 800–900°C leads to decomposition and formation of a ZnSαpoor defect spinel phase and a ZnS-rich phase with a defect wurtzite structure. The boundaries of the two-phase region at 830–860°C are approximately Zn_0,98Al_2.01S₄ (cubic α-phase, a α 10.007₂ Å (25°C)) and Zn_1.80Al_1.47S₄ (hexagonal wurtzite-phase, a = 3.76₀, c = 6.1₅ Å (25°C)). Mixtures of ZnS, Al and S with the composition Zn_xAl_8/3?2x/3S₄ and 0.33 ≤ x ≤ 0.98, which are heat treated at 830–860°C (70–140 h), yield after cooling to room temperature homogeneous products with a defect spinel structure. The miscibility gap at the composition Al₂S₃ · ZnS continues at higher temperatures with a shift of the phase boundaries and formation of high-temperature phases. A high-temperature modification of ZnAl₂S₄ does not exist up to 1080°C. When mixtures of ZnS, Al and S with 0.44 ≤ x ≤ 0.85 are heat treated at 1060–1080°C(72-96 h), a rhombohedra1 high-temperature phase (γ-phase) is obtained after cooling to room temperature, which has not previously been observed. I t s structure can be described as a defect structure of the ZnIn, S, type. With x = 1.00, after thermal treatment a t 1060-1080°C, a two-phase product is obtained, containing γ-phase in addition to an orthorhombic phase (β-phase, super-lattice of the wnrtzite type). The β-phase is the only phase occuring in products with 1.40 ≤ x ≤ 1.70. The solubility of Al, S, in ZnS (wurtzite) at 1060-1080°C with formation of a defect wurtzite structure, in which the cations are disordered, reaches as far as Zn_l.70?1.80Al_l.53?1.47S₄[Al₂S₃·(2.2-2.5)ZnS].