Synthesis, Decomposition and Crystallization Characteristics of Peroxo-Cetrato-Niobium: An Aqueous Niobium Precursor

Y. Narendar, Gary L. Messing

Research output: Contribution to journalArticle

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Abstract

The synthesis of peroxo-citrate-niobium, a novel aqueous precursor of niobium, is reported. Niobium oxalate was decomposed with acidified H2O2 to form a peroxo-niobium complex, which was reacted with citric acid at pH ∼ 7.5 to form the stable peroxo-citrato-niobium complex. IR and Raman spectroscopy indicate that the peroxo-citrato-niobium complex consists of tridentate bridging citrato and bidentate peroxo ligands. The aqueous complex is binuclear with peroxo groups chelated to niobium and the precipitated complex is polynuclear with bridging type peroxo groups. Due to kinetic limitations during crystallization, the formation of seven-coordinated niobium in peroxo-citrato-niobium energetically favors the formation of niobium oxides with seven-coordinated niobium, viz. TT-Nb2O5 and T-Nb2O5. Consequently, nanocrystalline metastable TT-Nb2O5, with a particle size of ∼25 nm, crystallizes from the peroxo-citrato-niobium complex at 580°C. On further heating, TT-Nb2O5 transforms to T-Nb2O5 at 800°C, M-Nb2O5 at 1000°C, and H-Nb2O5 at 1200°C. The nanometric particle size is retained after heating to 1200°C and H-Nb2O5 has an average crystallite size of 53 nm.

Original languageEnglish (US)
Pages (from-to)580-587
Number of pages8
JournalChemistry of Materials
Volume9
Issue number2
StatePublished - Feb 1 1997

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Niobium
Crystallization
Decomposition
Citric Acid
Particle size
Niobium oxide
Heating
Oxalates
Citric acid
Crystallite size
Raman spectroscopy
Infrared spectroscopy

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Chemical Engineering(all)
  • Materials Chemistry

Cite this

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title = "Synthesis, Decomposition and Crystallization Characteristics of Peroxo-Cetrato-Niobium: An Aqueous Niobium Precursor",
abstract = "The synthesis of peroxo-citrate-niobium, a novel aqueous precursor of niobium, is reported. Niobium oxalate was decomposed with acidified H2O2 to form a peroxo-niobium complex, which was reacted with citric acid at pH ∼ 7.5 to form the stable peroxo-citrato-niobium complex. IR and Raman spectroscopy indicate that the peroxo-citrato-niobium complex consists of tridentate bridging citrato and bidentate peroxo ligands. The aqueous complex is binuclear with peroxo groups chelated to niobium and the precipitated complex is polynuclear with bridging type peroxo groups. Due to kinetic limitations during crystallization, the formation of seven-coordinated niobium in peroxo-citrato-niobium energetically favors the formation of niobium oxides with seven-coordinated niobium, viz. TT-Nb2O5 and T-Nb2O5. Consequently, nanocrystalline metastable TT-Nb2O5, with a particle size of ∼25 nm, crystallizes from the peroxo-citrato-niobium complex at 580°C. On further heating, TT-Nb2O5 transforms to T-Nb2O5 at 800°C, M-Nb2O5 at 1000°C, and H-Nb2O5 at 1200°C. The nanometric particle size is retained after heating to 1200°C and H-Nb2O5 has an average crystallite size of 53 nm.",
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Synthesis, Decomposition and Crystallization Characteristics of Peroxo-Cetrato-Niobium : An Aqueous Niobium Precursor. / Narendar, Y.; Messing, Gary L.

In: Chemistry of Materials, Vol. 9, No. 2, 01.02.1997, p. 580-587.

Research output: Contribution to journalArticle

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AB - The synthesis of peroxo-citrate-niobium, a novel aqueous precursor of niobium, is reported. Niobium oxalate was decomposed with acidified H2O2 to form a peroxo-niobium complex, which was reacted with citric acid at pH ∼ 7.5 to form the stable peroxo-citrato-niobium complex. IR and Raman spectroscopy indicate that the peroxo-citrato-niobium complex consists of tridentate bridging citrato and bidentate peroxo ligands. The aqueous complex is binuclear with peroxo groups chelated to niobium and the precipitated complex is polynuclear with bridging type peroxo groups. Due to kinetic limitations during crystallization, the formation of seven-coordinated niobium in peroxo-citrato-niobium energetically favors the formation of niobium oxides with seven-coordinated niobium, viz. TT-Nb2O5 and T-Nb2O5. Consequently, nanocrystalline metastable TT-Nb2O5, with a particle size of ∼25 nm, crystallizes from the peroxo-citrato-niobium complex at 580°C. On further heating, TT-Nb2O5 transforms to T-Nb2O5 at 800°C, M-Nb2O5 at 1000°C, and H-Nb2O5 at 1200°C. The nanometric particle size is retained after heating to 1200°C and H-Nb2O5 has an average crystallite size of 53 nm.

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