Reaction Of Zirconium Research Articles

Reaction of zirconium(IV) with 2,3,4-trihydroxiphenylazo-5′-sulfonaphthalene in the presence of diantipyrilmethane and its homologues

The effect of diantipyrilmethane and its homologues on the complexation of zirconium(IV) with 2,3,4-trihydroxiphenylazo-5′-sulfonaphthalene is studied, and conditions for the formation of mixed-ligand complexes are determined. Correlations between the acidity constants of diantipyrilmethane and its homologues and the stability constants and the specific conductivity of complexes, and degree of contrast, and the change in the Gibbs free energy are found for the complexation reaction. A method is developed for the selective photometric determination of zirconium in pyrite containing modified quartz diorite.

Zirconium and hafnium oxoclusters as molecular building blocks for highly dispersed ZrO2 or HfO2 nanoparticles in silica thin films

A novel synthetic route for the preparation of ZrO2 or HfO2 nanoparticles homogeneously dispersed in SiO2 thin films was developed. This route is based on the copolymerisation of organically modified crystalline oxozirconium or oxohafnium clusters (M4O2(OMc)12, M = Zr, Hf; OMc = OC(O)–C(CH3)CH2) with (methacryloxymethyl)triethoxysilane (MAMTES, CH2C(CH3)C(O)O–CH2Si(OCH2CH3)3). These crystalline clusters, which are the precursors for the corresponding metal oxides (MO2), were prepared via the sol–gel route by reaction of zirconium or hafnium butoxide (M(OBu)4) with methacrylic acid. The copolymerisation of the clusters with the methacrylate-functionalised siloxane was photoinitaited by Irgacure 184 and allowed the anchoring of the cluster to the forming silica network. The solution was cast into films by dip-coating and UV cured (10 min, 125 W) to promote the copolymerisation of the methacrylate groups of the cluster with those of the silane. Transparent and homogeneous films 200–450 nm thick were obtained after calcination at 800 °C in air. This route allowed the production of a very homogeneous dispersion of the MO2 precursors inside the silica matrix. The surface and in-depth composition of the thin films was investigated through IR, X-ray photoelectron spectroscopy (XPS) and secondary ion mass spectrometry (SIMS). SIMS and XPS depth profiles evidenced a very homogenous distribution of both zirconium or hafnium throughout the silica films and sharp film–substrate interfaces. The surface morphology of the coatings was investigated through atomic force microscopy (AFM), which showed smooth, homogeneous and crack-free surfaces. Through X-ray diffraction (XRD) the crystallisation of hafnium and zirconium oxides was revealed, while the presence of isolated crystalline nanoparticles having a diameter of 5–10 nm was evidenced by transmission electron microscopy (TEM). A pull-off test indicated a very good adhesion of the films to the substrate.

Homoleptic phenolate complexes of zirconium(iv): syntheses and structural characterization of the first six coordinate complexes

Homoleptic phenolate complexes of zirconium, [Na(THF)2]2[Zr(OC6H4-2-Cl)6] and [NH2(CH3)2]2[Zr(OC6H4-2-Cl)6]·2THF, were synthesized and fully characterized. To our knowledge, these complexes are the first examples for homoleptic six coordinated phenolate complexes of zirconium. Anaerobic reaction of zirconium tetrachloride with six equivalents of sodium 2-chlorophenolate afforded [Na(THF)2]2[Zr(OC6H4-2-Cl)6] in excellent isolated yields. The geometry of the ZrO6 core is octahedral with some distortion due to interactions of the sodium cations with oxygen atoms of the 2-chlorophenolate groups. The sodium cations are bound to five oxygen atoms: three to 2-chlorophenolate groups and two to THF. The coordination sphere is completed by interaction with chloride substituents of three 2-chlorophenolate ligands. A second example of a six coordinate complex of zirconium, [NH2(CH3)2]2[Zr(OC6H4-2-Cl)6]·2THF, was synthesized by the reaction of zirconium tetrakis(dimethylamino) with six or four equivalents of 2-chlorophenol. The ZrO6 core adopts a distorted octahedral geometry. Distortion is caused by hydrogen bonding between the dimethylammonium cation and the oxygen atom of one 2-chlorophenolate ligand. 1H- and 13C-NMR spectroscopy revealed that [NH2(CH3)2]2[Zr(OC6H4-2-Cl)6]·2THF decomposes in solution. These observations illustrate the profound influence that weaker secondary interactions to the donor atoms can have on metal coordination geometry.

Reactions of Zirconium and Hafnium Atoms with Ammonia. Matrix Infrared Spectra and Density Functional Calculations of the MNH3 and H2MNH (M = Zr and Hf) Molecules

The reactions between zirconium and hafnium metal atoms and ammonia molecules have been studied using matrix isolation infrared absorption spectroscopy and density functional theoretical calculatio...

Adsorption and Reaction of Zirconium(IV) Nitrate on Polycrystalline Zirconia

The adsorption of zirconium nitrate ZN] on thin films of polycrystalline zirconia was investigated with temperature-programmed reaction mass spectrometry (TPR) and X-ray photoelectron spectroscopy (XPS). TPR measurements demonstrate that adsorbed ZN undergoes competitive desorption and reaction near 340 K. The reaction is the first in a series of steps that ultimately leads to formation. Several gas-phase products are formed as a result of ZN decomposition, including NO, and The gas-phase products evolve from two temperature envelopes centered at and with the envelopes at somewhat higher temperature than the NO and envelopes. Partitioning between the desorption and decomposition pathways is a function of the heating rate, β, during TPD, with the ZN desorption fraction varying between 0.05 at and 0.4 at The XPS measurements reveal that the zirconium oxidation state is constant at during the decomposition sequence. However, the identities of the gas-phase products suggest that the ligands undergo oxidation-reduction chemistry during decomposition. On the basis of the TPR and XPS measurements, it is proposed that adsorbed peroxides of formula and are intermediates on the decomposition pathway. Both peroxides contain states of oxygen that are oxidized relative to oxygen in ZN. © 2002 The Electrochemical Society. All rights reserved.

Interfacial reactions of zirconium and zirconium-alloy liquid metals with beryllia at elevated temperatures.

Argonne National Laboratory and Integrated Thermal Sciences, Inc. are developing crucible materials for melting reactive metals. A major part of this effort involves identifying reusable materials because they would have little or no interaction with the molten metals at elevated temperatures. Sessile drop-type experiments have been performed using pure zirconium and stainless steel-zirconium alloys (e.g., HT9-15Zr) on beryllia (BeO) substrates. The system was heated in high-purity argon to about 2000°C, held for 5 minutes, and cooled to room temperature. An external video camera monitored the interfacial interaction and wetting behavior. The zirconium melted and wetted the BeO at 1600°C, far below its melting point (1855°C). Post-test examinations show beryllium and oxygen dissolving in the zirconium metal. In addition, zirconium infiltrated the BeO substrate. No third phase reaction product was present at the zirconium-beryllia interface either at the top of the substrate or in the infiltrated region. HT9-15Zr also reacted with BeO; the alloy infiltrated partially into the BeO and formed a reaction-like layer attached to the ceramic substrate at the interface with the solidified metal. The rest of the liquid metal alloy did not wet the reaction product band. The results indicate that BeO is a poor crucible for the present application, but the observed wetting and infiltration phenomena are relevant to understanding the behavior of the liquid metal-ceramic interfaces.

Syntheses of zirconium (IV) complexes with Schiff-base ligand and their catalytic activities for polymerization of ethylene

The syntheses of a series of zirconium Schiff-base complexes are reported. These complexes are synthesized by the reaction of zirconium (IV) isopropoxide with the unusual kind of Schiff-base in 1:1 molar ratio, and they are characterized by EA, IR and MS. When activated by excess methylaluminoxane (MAO), all complexes are active for the polymerization of ethylene.

Reaction of Zirconium and Its Dihydride with Ammonia

The reaction of zirconium and its dihydride (particle size 40-100 μm) with ammonia was studied under the following conditions: 300-550°C, initial ammonia pressure 0.6-0.8 MPa, 10 wt % NH4Cl (relative to the initial amount of Zr and ZrH2). Depending on the pressure, temperature, size of the solid phase particles, and number of heating-cooling cycles, it is possible to prepare finely dispersed zirconium nitride or hydride.

(1,2-Benzenedicarbonitrile-κN)diiodo(phthalocyaninato-κ4N)zirconium(IV)

A new zirconium phthalocyanine complex [ZrI2(Pc){C6H4(CN)2}] (Pc = C32H16N8) was obtained in crystalline form by the reaction of zirconium with 1,2-dicyanobenzene (o-DCB) under a stream of iodine. The molecule is a reaction product of zirconium, iodine atoms and o-DCB molecules, four of which form the Pc macrocycle. The crystal structure of this compound consists of discrete molecules in which seven-coordinate Zr(IV) is surrounded by four N atoms of the phthalocyaninato ligand, two cis-iodide atoms and an N atom from one of the cyano groups of the fifth o-DCB molecule. A set of hydrogen-bonded interactions links the molecules in the crystal lattice.

Evolution of pore size distribution and average pore size of porous ceramic membranes during modification by counter-diffusion chemical vapor deposition

The modification of porous ceramic membranes by counter-diffusion chemical vapor deposition (CVD) is studied theoretically and experimentally. Numerical simulations of the evolution of the membrane permeance, average pore size and pore size distribution as a function of extent of modification are presented and compared with experimetal data. It is found that the change of the average pore size of the membranes after modification strongly depends on the initial pore size distribution of the membrane, CVD reaction kinetics and characterization method. Experimental data suggest that CVD of zirconia (and yttria) inside porous ceramic membranes by reaction of zirconium (and yttrium) chlorides with steam/air at elevated temperatures proceeds by quasi-zero reaction kinetics with respect to the oxidant, typical of non-stoichiometric supply of the reactants from opposite sides of the membrane. Under such conditions, CVD modification may result in a modest increase of the average pore size of coarse-pore ceramic membranes as suggested by numerical calculations and experimental data.

A TEM study of the interfaces and matrices of SiC-coated carbon fibre/aluminium composites made by the K2ZrF6 process

Carbon fibre-reinforced aluminium composites were pressurelessly cast by using K2ZrF6 as the wetting promotion agent. Transmission electron microscopy (TEM) and energy dispersed analysis of X-rays, (EDAX) were used. The results showed that interfacial reactions were very active after K2ZrF6 treatment. This was caused by the diffusion and reaction of zirconium in the surface of carbon fibres or in the SiC coating. Silicon alloying of aluminium could suppress the interfacial reactions by decreasing the activity of zirconium and changing intermetallic Al3Zr to Zr3Al4Si5, and building up the phase equilibrium between SiC, aluminium and silicon. The requested silicon content was higher than the equilibrium content of Al-Si-SiC system to suppress the SiC/Al interfacial reaction. A perfect interface was achieved in SiC-coated carbon fibre Al-12 wt% Si composite.

Synthesis and analytical application of tribromocarboxyarsenazo as a new chromogenic reagent for zirconium

A new chromogenic reagent tribromocarboxyarsenazo has been synthesized and the chromogenic reaction of this reagent with zirconium studied. In the medium of 0.5 mol/1 HCl, a blue complex is formed by the reaction of zirconium with tribromocarboxyarsenazo. The maximum absorption of the complex is at 633 nm, and the apparent molar absorptivity is 4.8 × 10 4 1/mol/cm. Beer's law is obeyed over the zirconium concentration range 0–18, μg/25 ml. The method has been applied to the determination of zirconium in aluminum, copper and magnesium alloys with satisfactory results.

Thermal decomposition of zirconium tetra-π-allyl and catalysis by the products

Thermal decomposition of zirconium tetra-π-allyl gives rise to a range of air-sensitive, non-stoichiometric products depending upon conditions. Hydrocarbyl residues are still attached to the zirconium atom and can be displaced by hydrolysis mainly as propylene and propane. The products of decomposition are catalytically active for both ethylene polymerisation and olefin hydrogenation. Reaction of zirconium tetra-π-allyl or its thermal decomposition product with hydrogen at elevated pressure generates a range of amorphous non-stoichiometric hydrides, which also have catalytic activity for olefin hydrogenation.

The Reaction of Zirconium with Selenium Vapour

"The Reaction of Zirconium with Selenium Vapour." Canadian Metallurgical Quarterly, 24(4), pp. 375–376

The Reaction of Zirconium with Selenium Vapour

"The Reaction of Zirconium with Selenium Vapour." Canadian Metallurgical Quarterly, 24(4), pp. 375–376

The reactions of zirconium(IV) bromide and zirconium(III) bromide and chloride with ammonia and zirconium(IV) bromide with ammonium cyanide

Unlike ZrCl 4, ZrBr 4 is not ammonolysed in liquid ammonia at temperatures up to −33 °C. The existence of ammoniates ZrBr 4nH 3 (n = 17, 12 and 9) at −36 °C has been established; at room temperature, the hexammine ZrBr 4 · 6NH 3 is the stable species which becomes ZrBr 4 · 2NH 3 at 200 °C. When treated with an excess of NH 4CN in liquid ammonia, complete replacement of bromide ions by cyanide occurs to give an inseparable mixture of Zr(CN) 4 · 2NH 3 and NH 4Br. The chloride and bromide of zirconium(III) also undergo no ammonolysis in liquid ammonia; the ammoniates stable at room temperature are ZrCl 3 · 2.5NH 3 and ZrBr 3 · 6NH 3.

The Performance of Zirconium Alloys in Sulfide Solutions

Abstract Zirconium Grades R 60702, R 60704, and R 60705 were investigated for deep sour gas well applications. Test methods include autoclave, constant strain, sustained load, and constant strain rate techniques. Test results indicate that these alloys have excellent resistance to general corrosion and to stress corrosion cracking in sulfide environments. No cracking was detected in all grades of zirconium in 5% NaCl + 0.5% CH3COOH + saturated H2S at room and boiling temperatures. Hydrogen sulfide seems to play a neutral role in the corrosion reactions of zirconium because of zirconium's low affinity for sulfur.

Mechanism and microkinetics of the formation of titanium and zirconium hydrides in a synthesis wave

Extensive research on the formation of metal hydrides in synthesis waves has so far failed to address the problems of the distributions of temperature, heat flux, degree of reaction, and rate of heat production over the zones. There is no evidence on the macrokinetics of the formation of metal hydrides directly in the wave. The authors have measured the temperature distributions and obtained evidence on the mechanism and macrokinetics in the formation of the various phases for Ti and Zr. The experiments were performed in a constant-pressure bomb on cylindrical specimens in hydrogen. The results show that thermal conductivity increases considerably in the reaction zone, with a linear interpolation formula closely describing the change, which is dependent on the completeness of reaction. The reaction of zirconium with hydrogen produces wide combustion zones, whereas titanium produces narrow ones. This means that the rate of hydrogenation of Zr is determined by the low temperature region, while the rate of hydrogenation in Ti is determined by the high temperature region. In the case of zirconium, the reaction zone may be divided into three parts according to the distribution of the heat production rate: I) rapidly varying; II) slowly varying; III) linearly varying. Themore » narrowness of the zones in Ti created excessive errors in differentiation, making it impracticable to calculate curves of heat production rate.« less

Kinetics of formation of solid iodides on zirconium

The reaction of zirconium with gaseous ZrI 4 was studied in the temperature range 300–500 °C. Specimens of zirconium were heated in sealed glass tubes with solid ZrI 4 which was kept at a lower temperature to maintain a fixed ZrI 4 pressure. The solid zirconium iodides that formed on the zirconium surface were examined by scanning electron microscopy. Initially, isolated clusters of ZrI crystals formed which subsequently coalesced into a layer of ZrI. A layer of diiodide formed on top of the layer of monoiodide in later stages. Preformed oxide layers less than 0.2 μm thick on the zirconium surface had no effect on the rate of the reaction with gaseous ZrI 4 but an oxide layer about 4 μm thick slowed the reaction markedly. The amount of iodide on the surface was determined by chemical analysis. In one series of timed experiments the amount of reaction was found to obey the cubic law for metal-gas reactions. The kinetics of the reaction resemble those of the Zr-O 2 reaction.

Reactions of zirconium(IV) isopropoxide with aliphatic and aromatic hydroxy esters. Part I, five-, six, seven- and eight-coordinated zirconium(IV) complexes

The reactions of zirconium(IV) isopropoxide with ethyl-α-(1-hydroxycyclohexyl) acetate (HOC 6H 10R), ethyl-β-hydroxy-β-phenyl propionate (HOCHPhR) and ethyl-β-hydroxy-β-phenyl butyrate (HOCMePhR), where (R = CH 2CO 2Et), have been carried out in refluxing benzene in different molar ratios under strictly anhydrous conditions. The dark brown products of the general composition, Zr(OPr i) 4−n·L n, (where L = hydroxy ester anion; n = 1–4) have been isolated and characterized on the basis of elemental analyses, molecular weight, infrared and proton magnetic resonance spectral studies.