Die Sulfate der Zirkonerde

Hauser, O.

doi:10.1002/zaac.19050450121

“…These solutions are widely used industrially as a source of soluble zirconium(IV), principally for the coating of pigments for paints. It has been known since the early 1900s that aqueous solutions of zirconium sulfate exhibit an extraordinarily complicated chemistry (Hauser, 1905(Hauser, , 1907, and at least four thorough studies of the nature of the solutions have been published since then (Falinski, 1941;D'Ans & Eick, 1951;Motov & Ritter, 1968;Checkmarev, Molokanova, Kharlambus & Yagodin, 1978). The variety of zirconium sulfate structures found in the solid state mirrors the complexity of the solutions from which they arise and Clearfield (1964) has attempted to rationalize the known structures.…”

Section: Introductionmentioning

confidence: 99%

Ab initiostructure determination of Zr(OH)₂SO₄.3H₂O using the conventional monochromatic X-ray powder diffraction

Gascoigne¹,

Tarling²,

Barnes³

et al. 1994

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The structure of Zr(OH)2SO4.3H2O has been determined ab initio by conventional powder diffractometry using monochromatic X‐rays. The pattern was indexed using the successive‐dichotomy method yielding cell dimensions a = 8.3645 (4), b = 15.1694 (9), c = 5.4427 (3) Å, and β = 103.145 (5)°. The space group is P21/c with Z = 2. 519 integrated intensities were extracted by whole‐pattern fitting and these were used to calculate the heavy‐atom positions by the Patterson method. Successive Fourier syntheses located the nine O atoms. Rietveld refinement was carried out over an angular range of 15 to 135°(2θ) and this converged with RF = 0.030, RB = 0.066, Rp = 0.085 and Rwp = 0.109. The structure consists of zigzag chains in the direction of [001] formed by edge‐sharing eightfold‐coordinated zirconium polyhedra in the shape of a bicapped trigonal prism. Sulfate tetrahedra bridge within chains whilst a network of hydrogen bonding stabilizes interchain interactions to form `corrugated sheets' parallel to the (100) plane; between these sheets lie `free' water molecules that do not take part in the polyhedra but do play a major role in the hydrogen‐bonding network. The ICDD Powder Diffraction File No. is 44–1493.

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“…If these species were precursors for the films, then their availability would be ensured for at least 24 h, which might be advantageous for controlled deposition. However, the medium still needs to be considered metastable because precipitation in zirconium sulfate solutions was observed after time spans as long as 2 weeks …”

Section: Discussionmentioning

confidence: 99%

“…Consistently, no particular species have been reported as being stable over a range of conditions in zirconium sulfate solutions. Rather, the chemistry may be ruled by complicated equilibria, and the time frame for changes in these solutions 40 indicates that equilibration is slow: Hauser observed precipitation in 0.5 M Zr(SO 4 ) 2 solutions only after 2 weeks, and Matijevic 34 managed to delay the precipitation in 0.2 mM Zr(SO 4 ) 2 by 10 h, 2 days, or 4 days in the presence of 1, 2, or 4 mM HNO 3 , respectively. Heating promoted hydrolysis…”

Section: Introductionmentioning

confidence: 99%

Particle Growth Kinetics in Zirconium Sulfate Aqueous Solutions Followed by Dynamic Light Scattering and Analytical Ultracentrifugation: Implications for Thin Film Deposition

Cölfen¹,

Schnablegger²,

Fischer³

et al. 2002

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Acidic aqueous solutions of Zr(SO4)2·4H2O can be used to deposit nanocrystalline zirconium oxide films on functionalized surfaces. Because zirconium hydrolyzes easily, such solutions are potentially unstable toward colloid formation and precipitation. Particle growth (conditions: 2 or 4 mM Zr(SO4)2, 0.4 or 0.6 N HCl, T = 323, 328, 333, or 343 K) was investigated using dynamic light scattering (DLS, in situ) and analytical ultracentrifugation (AUC, ex situ after quenching to 77 K and rethawing to 298 K). The AUC measurements revealed three stages of growth (all dimensions given are hydrodynamic radii): (1) coexistence of several discrete polynuclear complexes with r h = 0.43−2.29 nm; (2) particle size distribution with a single sharp maximum; (3) above r h ≈ 260 nm rapid transition to polydisperse medium with particles up to 100 μm. The DLS measurements revealed a linear increase of the hydrodynamic radii (z-average of particle population) from 5 nm to 1000−2500 nm with rates of 0.01−0.6 nm·s-1. The rates were proportional to the Zr(SO4)2 concentration, while the increase of the HCl concentration slowed or even inhibited growth. The apparent activation energy for this step was 136 kJ·mol-1. From the induction period before detection of first particles, initial growth rates (r h < 5 nm) were calculated to be ≈1 × 10-4 to 5 × 10-3 nm·s-1. Independent of the conditions, the two reaction rates were always proportional to each other, indicating linked rate laws. A 4 mM Zr(SO4)2 in 0.4 N HCl solution exhibited no particle growth at 323 K, but complexes of a constant radius (after 6, 12, and 24 h) of 1.16 nm were detected (AUC). Under these conditions, films were deposited and their thickness increased linearly with time, specifically by 2.1 × 10-4 nm·s-1. This rate corresponds to the initial growth rate in solution. In contrast to films grown from media with significant particle growth, these films showed surfaces free of attached particles, cracks, and holes.

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“…Consistently, no particular species have been reported as being stable over a range of conditions in zirconium sulfate solutions. The time frame for changes in these solutions [83] indicates that equilibration is slow: Precipitation in 0.5 M Zr(SO 4 ) 2 solutions was observed only after 2 weeks [86], and precipitation in 0.2 mM Zr(SO 4 ) 2 could be delayed by 10 h, 2 days, or 4 days through dissolving the salt in 1, 2, or 4 mM HNO 3 , respectively [77]. Heating promotes hydrolysis [87].…”

Section: Formation Of Primary Solidmentioning

confidence: 99%

Oxo‐Anion Modified Oxides

Jentoft

¹

2008

Handbook of Heterogeneous Catalysis

1

0

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The sections in this article are Introduction Classification Variety of Materials and Focus Target Properties Structure–Activity Relationships Effect of Sulfate and Other Oxo‐Anions Preparation Routes Formation of Primary Solid Formation of Pure Hydrous Zirconia Formation of Sulfate‐Containing Hydrous Zirconia Template‐Directed Formation of Primary Solid Commercially Available Precursors Anion‐Modification of Primary Solid Addition of Oxo‐Anions to Primary Solid in Liquid Medium Sulfation of Primary Solid via Gas Phase Introduction of Oxo‐Anions Using Solid Precursors Addition of Promoters (Optional) Promoters Structure–Activity Relationships Effect of Promoters Addition of Promoters Calcination Events Occurring During Calcination Effect of Bed Volume and Packing Effect of Calcination Temperature on Physical Properties Effect of Calcination Temperature on Catalytic Performance Effect of Holding Time Calcination: A Summary Sulfation of Thermally Treated Crystalline Oxides Sulfation with Aqueous Solutions (Solid–Liquid Phase) Sulfation via Gas Phase (Solid–Gas Phase) Sulfation of Zirconia using Solid Sulfate Precursors Addition of Noble Metals Activation Summary

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Die Sulfate der Zirkonerde

Cited by 16 publications

References 3 publications

Ab initiostructure determination of Zr(OH)₂SO₄.3H₂O using the conventional monochromatic X-ray powder diffraction

Ab initiostructure determination of Zr(OH)₂SO₄.3H₂O using the conventional monochromatic X-ray powder diffraction

Particle Growth Kinetics in Zirconium Sulfate Aqueous Solutions Followed by Dynamic Light Scattering and Analytical Ultracentrifugation: Implications for Thin Film Deposition

Oxo‐Anion Modified Oxides

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Die Sulfate der Zirkonerde

Cited by 16 publications

References 3 publications

Ab initiostructure determination of Zr(OH)2SO4.3H2O using the conventional monochromatic X-ray powder diffraction

Ab initiostructure determination of Zr(OH)2SO4.3H2O using the conventional monochromatic X-ray powder diffraction

Particle Growth Kinetics in Zirconium Sulfate Aqueous Solutions Followed by Dynamic Light Scattering and Analytical Ultracentrifugation: Implications for Thin Film Deposition

Oxo‐Anion Modified Oxides

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Product

Resources

About

Ab initiostructure determination of Zr(OH)₂SO₄.3H₂O using the conventional monochromatic X-ray powder diffraction

Ab initiostructure determination of Zr(OH)₂SO₄.3H₂O using the conventional monochromatic X-ray powder diffraction