Thermal Study of the Ceramic Pigments CoxZn(7−x)Sb2O12

Using the Pechini method, pigments with spinel structure (Zn₇Sb₂O₁₂)were synthesized by substitution of the cation Zn²⁺ by Co²⁺, in compounds with different concentrations of Sb₂O₃. The doping resulted in Co_xZn_(7–x)Sb₂O₁₂ phases(x=1–7) that were isomorphs to spinel, denominated as samples A and B. After thermal treatment at 400°C for 1 h, the powders were characterized by thermogravimetry(TG) and differential thermal analysis (DTA). The results indicate a different behavior whena higher amount of Sb₂O₃ is used, due to the presence of a secondary phase (ilmenite). This revised version was published online in July 2006 with corrections to the Cover Date.     

Spektralphotometrische Ermittlung der Koordinationsverhältnisse in Kristallgittern, 2. Mitt.: Die Dimorphie von Zn7Sb2O12

Zusammenfassung Im System ZnO–Sb₂O₅ existieren zwei Spinellphasen (I) und (III) gleicher Zusammensetzung Zn₇Sb₂O₁₂. Außerdem konnte noch eine weitere Modifikation (II) mit einer niedrigsymmetrischen Struktur aufgefunden werden.In (II) und (III) wurden Cu²⁺, Ni²⁺ und Co²⁺ als farbgebende Kationen eingebaut. Die spektralphotometrische Untersuchung ergab, daß Zn²⁺ in (II) sowohl oktaedrisch als auch tetraedrisch koordiniert ist. Im Spinell (III) wird Cu²⁺ sowohl in Tetraeder-und Oktaederlücken, Ni²⁺ nur in Oktaeder- und Co²⁺ vorwiegend in Oktaederlücken eingebaut.In the system ZnO–Sb₂O₅ exist two phases (I) and (III) with the spinel structure and the same composition Zn₇Sb₂O₁₂. Besides these another modification (II) with a structure of lower symmetry could be found.The colouring cations Cu²⁺, Ni²⁺, Co²⁺ have been incorporated in (II) and (III). The spectrophotometrical investigation shows that Zn²⁺ occupies in (II) octahedral and tetrahedral sites. In the spinel (III) Cu²⁺ is incorporated tetrahedrally and octahedrally, Ni²⁺ only octahedrally and Co²⁺ predominantly octahedrally.Mit 4 Abbildungen1. Mitt.:H. Kasper, Z. anorg. allgem. Chem. (im Druck).     

Pyrochlore phases in the system ZnOBi2O3Sb2O5: II. Crystal structures of Zn2Bi3.08Sb2.92O14+δ and Zn2+xBi2.96−(x−y)Sb3.04−yO14.04+δ

Rietveld refinement of combined X-ray and neutron diffraction data has, within errors, confirmed the stoichiometries of two, cubic pyrochlore phases in the ZnOBi₂O₃Sb₂O₅ system. Neither phase has the ‘ideal’ stoichiometry, Zn₂Bi₃Sb₃O₁₄. One phase, P₁, is a Zn-rich, Bi-deficient solid solution Zn_2+xBi_{2.96−(x−y)}Sb_3.04−yO_14.04+δ. The other, P₂, is a Bi-rich line phase, stoichiometry Zn₂Bi_3.08Sb_2.92O_14+δ. Both structures have a mixture of Bi, Zn on the A-sites and Zn, Sb on the B-sites. However, Zn is displaced off-centre in the A-sites to achieve lower co-ordination number with realistic ZnO bond lengths. Additional structural complexities arise from: displacement of O(2) atoms; partial occupancies of O(1) and O(2) sites; partial occupancy of a third, interstitial oxygen site, O(3). Since the multiplicities of the off-centre sites are much higher than those of the ideal positions, there is considerable possibility for correlated short range order throughout the structures.     

Ternary K2Zn5As4‐type pnictides Rb2Cd5As4 and Rb2Zn5Sb4, and the solid solution Rb2Cd5(As,Sb)4

Dirubidium pentacadmium tetraarsenide, Rb₂Cd₅As₄, dirubidium pentazinc tetraantimonide, Rb₂Zn₅Sb₄, and the solid‐solution phase dirubidium pentacadmium tetra(arsenide/antimonide), Rb₂Cd₅(As,Sb)₄ [or Rb₂Cd₅As_3.00(1)Sb_1.00(1)], have been prepared by direct reaction of the component elements at high temperature. These compounds are charge‐balanced Zintl phases and adopt the orthorhombic K₂Zn₅As₄‐type structure (Pearson symbol oC44), featuring a three‐dimensional [M₅Pn₄]²⁻ framework [M = Zn or Cd; Pn is a pnicogen or Group 15 (Group V) element] built of linked MPn₄ tetrahedra, and large channels extending along the b axis which host Rb⁺ cations. The As and Sb atoms in Rb₂Cd₅(As,Sb)₄ are randomly disordered over the two available pnicogen sites. Band‐structure calculations predict that Rb₂Cd₅As₄ is a small‐band‐gap semiconductor and Rb₂Zn₅Sb₄ is a semimetal.     

AM2X2-Verbindungen mit CaAl2Si2-Struktur. XI. Struktur und Eigenschaften der Verbindungen ACd2X2 (A: Eu,Yb; X: P,As, Sb)

AM₂X₂ Compounds with the CaAl₂Si₂-Type Structure. XI. Structure and Properties of ACd₂X₂ (A: Eu, Yb; X: P, As, Sb) EuCd₂P₂, EuCd₂As₂, EuCd₂Sb₂, YbCd₂As₂, and YbCd₂Sb₂ were prepared by heating mixtures of the elements and investigated by means of single-crystal X-ray methods. The compounds are isotypic (lattice constants see “Inhaltsübersicht”) and crystallize in the CaAl₂Si₂-type structure (P3 m1; Z = 1). Magnetic measurements showed, that Eu is divalent and that the compounds order magnetically at low temperatures.     

SbxZn1-xO1+x/2及其壳聚糖复配物的制备和抗菌性能

采用溶胶-凝胶法制备了SbxZn1-xO1+x/2及其壳聚糖的复配物,通过X-射线衍射仪(XRD)、傅里叶变换红外光谱仪(FTIR)、扫描电子显微镜(SEM)和透射电子显微镜(TEM)等表征了样品的物相结构、组成和微观形貌。以大肠杆菌、白色念珠菌和金黄色葡萄球菌为测试菌种,研究了样品的抗菌性能。结果表明,SbxZn1-xO1+x/2的抗菌活性优于纯ZnO,其中x=0.05的样品活性最好;复配物的抗菌活性明显优于单一组分,当Sb0.05Zn0.95O1.025和壳聚糖质量比mSZ/mCS=2时,样品抗菌性能最佳。     

Structural and physical properties of Mg3−xZnxSb2 (x=0-1.34)

The Mg_3−xZn_xSb₂ phases with x=0-1.34 were prepared by direct reactions of the elements in tantalum tubes. According to the X-ray single crystal and powder diffraction, the Mg_3−xZn_xSb₂ phases crystallize in the same P3¯m1 space group as the parent Mg₃Sb₂ phase. The Mg_3−xZn_xSb₂ structure is different from the other substituted structures of Mg₃Sb₂, such as (Ca, Sr, Ba) Mg₂Sb₂ or Mg_5.23Sm_0.77Sb₄, in a way that in Mg_3−xZn_xSb₂ the Mg atoms on the tetrahedral sites are replaced, while in the other structures Mg on the octahedral sites is replaced. Thermoelectric performance for the two members of the series, Mg₃Sb₂ and Mg_2.36Zn_0.64Sb₂, was evaluated from low to room temperatures through resistivity, Seebeck coefficient and thermal conductivity measurements. In contrast to Mg₃Sb₂ which is a semiconductor, Mg_2.36Zn_0.64Sb₂ is metallic and exhibits an 18-times larger dimensionless figure-of-merit, ZT, at room temperature. However, thermoelectric performance of Mg_2.36Zn_0.64Sb₂ is still poor and it is mostly due to its large electrical resistivity.     

Phase relations and structural properties of the ternary narrow gap semiconductors Zn5Sb4In2−δ (δ=0.15) and Zn9Sb6In2

A systematic study of the Zn-rich corner of the ternary system Zn-Sb-In revealed the presence of two ternary compounds: stable Zn₅Sb₄In_2−δ (δ=0.15) and metastable Zn₉Sb₆In₂ with closely related crystal structures. Their common motif is a tetragonal basic structure of 3²434 nets formed by the Sb atoms. The nets are stacked in antiposition to yield layers of square antiprisms sharing edges plus intervening tetracapped tetrahedra (tetreadersterns). The majority of Zn atoms occupy peripheral tetrahedra of such tetraedersterns, which produces frameworks with a composition “ZnSb”. These frameworks represent orthorhombic superstructures: (2×1×1) for Zn₅Sb₄In_2−δ (Z=4) and (2×3×1) for Zn₉Sb₆In₂ (Z=8) with respect to the tetragonal arrangement of Sb atoms. The In and remaining Zn atoms are distributed in the channels formed by the square antiprisms. Phase relations in the Zn-Sb-In system are complex. Crystals of metastable Zn₉Sb₆In₂ are regularly intergrown with various amounts of Zn₅Sb₄In_2−δ. Additionally, a monoclinic variant to orthorhombic Zn₉Sb₆In₂ could be identified. Zn₉Sb₆In₂ decomposes exothermically into a mixture of Zn₅Sb₄In_2−δ, Zn₄Sb₃ and elemental Zn at around 480 K. Both Zn₅Sb₄In_2−δ and Zn₉Sb₆In₂ are poor metals with resistivity values that are characteristic of heavily doped or degenerate semiconductors (0.2−3 m Ω cm at room temperature).     

Unknown thermal properties of ZnSb2O6 and Zn7Sb2O12 compounds

The investigations by XRD, DTA/TG and IR methods show that two compounds: ZnSb₂O₆ and Zn₇Sb₂O₁₂ are formed in the ZnO-α-Sb₂O₄ system in air. Oxygen contained in the air participates in the synthesis of these compounds. ZnSb₂O₆ was observed as an intermediate phase, during the Zn₇Sb₂O₁₂ synthesis. The temperature of the β→α-Zn₇Sb₂O₁₂ transition was fixed at 1225±10°C. The mechanisms of the reactions of ZnSb₂O₆ and Zn₇Sb₂O₁₂ thermal decomposition have been proposed. The IR studies of α and β-Zn₇Sb₂O₁₂ have initially indicated that the structures of both polymorphous forms differ in the reciprocal connection of the SbO₆ and ZnO₆ octahedra and the ZnO₄ tetrahedra.     

Achieving Near-unity Photoluminescence Quantum Yields in Organic-Inorganic Hybrid Antimony (III) Chlorides with the [SbCl5] Geometry

Hybrid organic–inorganic antimony halides have attracted increasing attention due to the non-toxicity, stability, and high photoluminescence quantum yield (PLQY). To shed light on the structural factors that contribute to the high PLQY, five pairs of antimony halides with general formula A₂SbCl₅ and A₂Sb₂Cl₈ are synthesized via two distinct methods and characterized. The A₂SbCl₅ type adopts square pyramidal [SbCl₅] geometry with near-unity PLQY, while the A₂Sb₂Cl₈ adopts seesaw dimmer [Sb₂Cl₈] geometry with PLQY≈0 %. Through combined data analysis with the literature, we have found that A₂SbCl₅ series with square pyramidal geometry generally has much longer Sb⋅⋅⋅Sb distances, leading to more expressed lone pairs of Sb^III. Additional factors including Sb−Cl distance and stability of antimony chlorides may also affect PLQY. Our targeted synthesis and correlated insights provide efficient tools to precisely form highly emissive materials for optoelectronic applications.     

Kathodolumineszenz der neuen Selten Erd-aktivierten Granate A2A′Sb2Zn3O12 (A = Gd,Y; A′ = Sr,Ca)

By activation of the new garnet host lattices A₂A′Sb₂Zn₃O₁₂ (A = Gd, Y; A′ = Sr, Ca) with the trivalent rare earth ions (Ln³⁺ = Pr, Eu, Tb, Tm) a cathodoluminescence in the visible region is observed. The influence of the electronic structure and concentration of the activator on the relative intensity as well as the host lattice participation in the energy transfer processes are discussed.     

Thermal study of CoxZn7-xSb2O12 spinel obtained by pechini method using different alcohols

With the aim of obtaining materials with applications in pigments, Co_xZn_7-xSb₂O₁₂ spinels were synthesized using the Pechini method. This method consists in the formation of a polymeric net, where the metallic cations are homogeneously distributed. In this work, two types of alcohol (ethyl glycol and ethylene glycol) were used for the synthesis of a zinc antimoniate spinel, Co_xZn_7-xSb₂O₁₂ (x=0-7). The materials were characterized by termogravimetry (TG) and differential thermal analysis (DTA). TG results indicated a decrease in total mass loss when cobalt was added to the solution substituting zinc, for samples prepared using the two different alcohols. Decomposition temperatures, obtained by TG and DTA, presented a decreasing behavior as cobalt was added to the material. In relation to the alcohols, all results indicated a better polymerization of the resin when ethylene glycol was used, being the most indicated one for cation immobilization. X-ray diffraction did not show differences between the two alcohols - both presented the spinel phase (Co, Zn)_2.33Sb₀.₆₇O₄. Samples with higher quantity of cobalt also presented ilmenite phase (Co, Zn)Sb₂O₆. This revised version was published online in August 2006 with corrections to the Cover Date.     

ASb2(SO4)2(PO4) (A = H3O+, K,Rb): Layered Structure Containing Ordered Sulfate and Phosphate Anions

Three compounds ASb₂(SO₄)₂(PO₄) (A = H₃O⁺, K, Rb) were obtained from the reactions of Sb₂O₃, A₂CO₃ (A = Li, Rb) or K₂SO₄ and NH₄H₂PO₄ in H₂SO₄ (98 %) at 220–250 °C. Their structures were determined by single‐crystal X‐ray diffraction. All compounds crystallize in the triclinic space group P$\bar{1}$ (no.2) and are isostructural. The crystal structures consist of two‐dimensional ²_∞[Sb₂(SO₄)₂(PO₄)]^– anionic layers and alkali cations, which are located between anionic layers. The anionic layers are composed of [SbO₄] ψ‐trigonal bipyramids, [SbO₅] ψ octahedra, [SO₄] tetrahedra, and [PO₄] tetrahedra. All compounds are characterized by solid state UV/Vis/NIR diffuse reflectance spectra, FT‐IR spectroscopy, and Raman spectroscopy.     

Li17Sb13S28: A New Lithium Ion Conductor and addition to the Phase Diagram Li2S–Sb2S3

Li₁₇Sb₁₃S₂₈ was synthesized by solid‐state reaction of stoichiometric amounts of anhydrous Li₂S and Sb₂S₃. The crystal structure of Li₁₇Sb₁₃S₂₈ was determined from dark‐red single crystals at room temperature. The title compound crystallizes in the monoclinic space group C2/m (no. 12) with a=12.765(2) Å, b=11.6195(8) Å, c=9.2564(9) Å, β=119.665(6)°, V=1193.0(2) ų, and Z=4 (data at 20 °C, lattice constants from powder diffraction). The crystal structure contains one cation site with a mixed occupation by Li and Sb, and one with an antimony split position. Antimony and sulfur form slightly distorted tetragonal bipyramidal [SbS₅E] units (E=free electron pair). Six of these units are arranged around a vacancy in the anion substructure. The lone electron pairs E of the antimony(III) cations are arranged around these vacancies. Thus, a variant of the rock salt structure type with ordered vacancies in the anionic substructure results. Impedance spectroscopic measurements of Li₁₇Sb₁₃S₂₈ show a specific conductivity of 2.9×10^?9 Ω^?1 cm^?1 at 323 K and of 7.9×10^?6 Ω^?1 cm^?1 at 563 K, the corresponding activation energy is E_A=0.4 eV below 403 K and E_A=0.6 eV above. Raman spectra are dominated by the Sb?S stretching modes of the [SbS₅] units at 315 and 341 cm^?1 at room temperature. Differential thermal analysis (DTA) measurements of Li₁₇Sb₁₃S₂₈ indicate peritectic melting at 854 K.     

Exploring LiZnNbO4 as a Host for New Colored Compounds: Synthesis,Structure, and Material Properties of NbZn1-x Mx LiO4 (M=Mn,Co, Ni,Fe) and Nb1-ySby Zn1-x Mx LiO4 (M=Co,Ni)

The non - centrosymmetric tetragonal inverse spinel structure of LiZnNbO₄ has been explored with a view to prepare new colored compounds. The substitution of Co²⁺, Ni²⁺, Fe²⁺, Mn²⁺, and Cu²⁺ ions were attempted in the place of Zn²⁺ ions and Sb⁵⁺ ions in place of Nb⁵⁺ ions. The studies indicated that 0.75 Zn²⁺ ions in LiZnNbO₄ can be replaced by Co²⁺ ions and 0.5 Zn²⁺ ions in LiZnNb_0.5Sb_0.5O₄ compound. The substitution of Co²⁺ ions gives rise to different shades of blue color in Li(Zn_1-xCo_x)NbO₄ compounds and from ink blue to blue-green color in Li(Zn_1-xCo_x)(Nb_0.5Sb_0.5)O₄ compounds. The different colors observed in the present study were explained by the traditional allowed d-d transitions as well as the metal-to-metal charge transfer (MMCT) transitions involving Nb⁵⁺ (4d⁰) ions and partially filled 3d electrons. The SHG studies indicate that the prepared compounds are SHG active. All the compounds exhibit reasonable dielectric behavior with low loss. The XPS studies confirm the oxidation states of the different substituted ions. Raman studies indicate variations in the bands due to the substitutions in the parent LiZnNbO₄ phase. Magnetic studies on the Co²⁺ ions substituted compounds suggest antiferromagnetic behavior.     

Polymorphie bei APd2X2-Verbindungen (A = Sr,Ba; X = As,Sb)

Polymorphism of APd₂X₂-Compounds (A = Sr, Ba; X = As, Sb) SrPd₂Sb₂ crystallizes at room temperature in the CaBe₂Ge₂-type structure (lattice constants see “Inhaltsübersicht”); a high-temperature modification with ThCr₂Si₂-type structure was obtained by quenching samples from above 730°C. The same structure was found for the high-temperature modification of BaPd₂As₂ which can be prepared by quenching from above 720°C. For (ThCr₂Si₂-structure) no phase transition could be observed.     

Ternary Antimonide EuSn3Sb4 and Related Metallic Zintl Phases

The ternary Zintl compound europium tin antimonide, EuSn₃Sb₄, has been synthesized at 900°C in the presence of a tin flux, and its structure has been determined by single-crystal X-ray diffraction methods. It crystallizes in the orthorhombic space group D¹⁶_2h-Pnma with a=9.954(2), b=4.3516(7), c=22.650(4) Å, and Z=4 at 22°C. EuSn₃Sb₄ is isostructural to SrSn₃Sb₄; it possesses channels defined by an anionic framework of shared SnSb₄ tetrahedra, SnSb₃ trigonal pyramids, and Sb–Sb zigzag chains, and it is filled by Eu²⁺ cations. Resistivity measurements indicate weakly metallic behavior for ASn₃Sb₄ (A=Eu, Sr) and the structurally related Ba₂Sn₃Sb₆. The anisotropic metallic nature of these compounds is explained through extended Hückel band structure calculations.     

Experimente zur Mischkristallbildung zwischen Zinktantalaten und -antimonaten: ZnTa2−xSbxO6 und Zn4Ta2−xSbxO9

Experiments about the Mixed Crystal Formation between Zincoxotantalates and -antimonates: ZnTa_2?xSb_xO₆ and Zn₄Ta_2?xSb_xO₉ In the area of substituted oxotantalates of zinc two new phases of the composition A: ZnTa_1·8Sb_0·2O₆ and B: Zn₄Ta_1·2Sb_0·8O₉ were prepared and investigated by X-ray single crystal technique. A crystallizes with tetragonal symmetry (space group D–P4₂/mnm, a = 4.7314; c = 9.2160 Å; Z = 2). B is monoclinic (space group C–C2/c; a = 15.103; b = 8.839; c = 10.378 Å; β = 93.81°; Z = 8). A crystallizes with trirutile structure, although there is a small replacement of Ta⁵⁺ by Sb⁵⁺. B maintains the Zn₄Ta₂O₉ structure. One of the point positions of the M⁵⁺ ions is occupied statistically by Ta⁵⁺/Sb⁵⁺ and Zn²⁺. B is a metastable compound.     

Syntheses, structure and rare earth metal photoluminescence of new and known isostructural A2Mo4Sb2O18 (A=Ce, Pr, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) compounds

Nine new A₂Mo₄Sb₂O₁₈ (A=Ce, Pr, Eu, Tb, Ho, Er, Tm, Yb, Lu) compounds have been synthesized by solid-state reactions. They are isostructural with six reported analogues of yttrium and other lanthanides and the monoclinic unit cell parameters of all fifteen of them vary linearly with the size of A³⁺ ion. Single crystal X-ray structures of eight A₂Mo₄Sb₂O₁₈ (A=Ce, Pr, Eu, Gd, Tb, Ho, Er, Tm) compounds have been determined. Neat A₂Mo₄Sb₂O₁₈ (A=Pr, Sm, Eu, Tb, Dy, Ho, Er, Tm) compounds exhibit characteristic rare earth metal photoluminescence.     

Syntheses and characterization of zero-dimensional molybdoantimonites, A2(Mo4Sb2O18) (A=Y, La, Nd, Sm, Gd and Dy)

Six new isostructural A₂(Mo₄Sb₂O₁₈) (A=Y, La, Nd, Sm, Gd and Dy) compounds have been synthesized by solid-state reactions and characterized by single crystal X-ray diffraction and spectroscopic techniques. They crystallize in C2/c space group with 4 formula units and contain A³⁺ cations and discrete centrosymmetric anionic (Mo₄Sb₂O₁₈)⁶⁻ aggregates, made of tetrahedral MoO₄ and disphenoidal SbO₄ moieties. They exhibit characteristic Sb³⁺ photoluminescence.