EXAFS study of zirconium alkoxides as precursors in the sol-gel process: II. The influence of the chemical modification

Peter, D.; Ertel, Teja S.; Bertagnolli, Helmut

doi:10.1007/bf00486706

Cited by 38 publications

(39 citation statements)

References 13 publications

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“…XANES results show that Zr is always in a dodecahedral geometry both in lactate solutions and in polyacrylate gels. This coordination is different from that found in Zr-alkoxide system (Peter et al, 1995). In that case the number of oxygen atoms in the first coordination sphere of Zr (Zr-O distance 2.2Å) increases from 6 to 8 during gelation.…”

Section: Resultscontrasting

confidence: 76%

“…In the presence of strong complexing ligand, and under conditions which prevents hydrolysis (i.e. low pH and excess of ligands) complex Zr(ligand)4 represents the major species (Peter et al, 1995). A polymerization of such complexes, leading to the formation of the Zr dimer: Zr2(ligand)6 (Clearfield, 1964, Intorre and Martell, 1960, Peter et al, 1994 could occur if the pH slightly is increased.…”

Section: Introductionmentioning

confidence: 99%

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Zirconium speciation in lactate solutions and polyacrylate gels

Rose¹,

Chauveteau²,

Tabary³

et al. 2001

J Synchrotron Radiat

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Controlling gelation kinetics is an important objective for several applications (ceramic and thin film syntheses, reduction in permeability of porous rock, etc). There is a growing interest in studying the gelation of polymers by zirconium, a crosslinker of lower toxicity than the chromium which is still commonly used. XAS at the Zr K-edge was performed at the European Synchrotron Radiation Facility (ESRF) on the BM32 beamline. The fluorescence detection was used to carry out successful in situ speciation at concentrations as low as 36 ppm. The Zr speciation was determined both in ZrLa (where La stands for lactate) aqueous solutions and in gels of a terpolymer of acrylamide having 2% of zirconium reactive acrylate side groups and 2% of sulfonate groups introduced to prevent syneresis. XANES results show that Zr is always in a dodecahedral geometry. In ZrLa solutions, EXAFS results indicate that Zr species grow from a dimer Zr2(La)6 to a tetramer (Zr4(La)x) and then to larger polymers resulting from tetramer associations, as the Zr concentration decreases from 51840 ppm to 36ppm. In polymer gels, Zr species appear to be dimers at pH 6 while tetramers are found when gelation occurred at pH 7. Calculations taking into account multiple scattering effects as well as dynamic molecular calculation confirmed conclusions derived from conventional EXAFS analysis.

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Section: Resultscontrasting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

Zirconium speciation in lactate solutions and polyacrylate gels

Rose¹,

Chauveteau²,

Tabary³

et al. 2001

J Synchrotron Radiat

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“…42 In acetic acid-modified PZT sol the number of Zrneighbors is 0.8, noticeably less than 2.9 and 2.5 for unmodified and Acac-modified PZT, respectively. For the acetic acidmodified PZT sol, the dimeric zirconium units with bridging alkoxide groups are assumed in agreement with the structure proposed by Peter et al 43 for the Zr-propoxide in parent alcohol solution.…”

Section: Resultsmentioning

confidence: 95%

Homogeneity issues in chemical solution deposition of Pb(Zr,Ti)O3 thin films

Malič

Kosec

Arčon

et al. 2005

Journal of the European Ceramic Society

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“…In contrast, Peter et al 31 observed that upon addition of acetylacetone to Zr butoxide in a strongly diluted (0.03 molal) n-butanol solution, dimers were obtained with two moles and monomers with four moles of acetylectone. The difference could arise from the dilution, and the choice of the solvent, 2-methoxyethanol in our case, and consequently, its exchange reaction with the original Zr propoxide.…”

Section: Zr-solsmentioning

confidence: 90%

Homogeneity of Pb(Zr,Ti)O3 thin films by chemical solution deposition: Extended x-ray absorption fine structure spectroscopy study of zirconium local environment

Malič

Arčon

Kodre

et al. 2006

Journal of Applied Physics

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Sols for Pb(Zr 0.53 Ti 0.47)O 3 (PZT) thin films were prepared by 2-methoxyethanol route from lead acetate, titanium n-propoxide and zirconium n-propoxide, the latter either unmodified or modified with acetylacetone or acetic acid in a 2/1 molar ratio, and deposited on sapphire (0001). By Zr K-edge Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy , the structural changes in the Zr local environment, induced by the addition of the two modifiers, were followed from the synthesis of the PZT sol and to the transition to the amorphous film. In the unmodified PZT sol segregation of Zr species occurs from the original dimers present in the Zr propoxide solution in 2-methoxyethanol. The immediate neighborhood of Zr atoms changes markedly at the transition from the sol to the amorphous film: the local structure around Zr atoms is similar to the one found in tetragonal zirconia particles. The modification of Zr propoxide with acetylacetone in 2-methoxyethanol results in Zr monomers. In PZT sol clustering of Zr species is observed continuing into the amorphous film. By modification with acetic acid the original dimeric structure of the Zr precursor is retained in the PZT sol and further in the amorphous film. Selective modification of Zr alkoxide with acetic acid therefore results in a more homogeneous distribution of Zr atoms in the PZT sol and amorphous film than in both as-received or acetylacetone-modified Zr propoxide.

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EXAFS study of zirconium alkoxides as precursors in the sol-gel process: II. The influence of the chemical modification

Cited by 38 publications

References 13 publications

Zirconium speciation in lactate solutions and polyacrylate gels

Zirconium speciation in lactate solutions and polyacrylate gels

Homogeneity issues in chemical solution deposition of Pb(Zr,Ti)O3 thin films

Homogeneity of Pb(Zr,Ti)O3 thin films by chemical solution deposition: Extended x-ray absorption fine structure spectroscopy study of zirconium local environment

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