Comparative study of {beta}-nickel molybdate phase obtained by conventional precipitation and the sol-gel method
Various samples of {beta}-NiMoO{sub 4} phase consisting of nickel and molybdenum in a stoichiometric ratio were prepared by precipitation from nickel nitrate hexahydrate and ammonium heptamolybdate, and also in presence of Si(OCH{sub 3}){sub 4} and Si(OEt){sub 3}(CH{sub 2}){sub 3}NH(CH{sub 2})NH{sub 2} using the sol-gel method. The stabilised {beta}-NiMoO{sub 4} phase is synthesised using the sol-gel technique. The development of this phase is achieved by using a direct crystallisation in the silica matrix due to a high dispersion of Ni and Mo salts into silica gels derived from silicon alkoxides hydrolysis and condensation reactions. The mutual influences in hydro-alcoholic solutions between the two growing phases, i.e. the molybdate crystallites ions and the silica colloidal oligomers particles, cause a dramatic increase in the gelation rate. The gel thermal treatment causes the ionic species migration to form highly dispersed nanometer-sized NiMoO{sub 4} crystallites of ca.120 nm. XRD, Raman, TG-DTG, and XPS techniques were used for the characterisation of the material. The solids are semicrystalline materials with a surface area of 280 m{sup 2} g{sup -1}. DTG and XPS analyses provide evidence for the interactions between SiO{sub 2} and NiMoO{sub 4} systems which are responsible for the stabilisation of {beta}-NiMoO{sub 4}. Unsupported {beta}-NiMoO{sub 4} is a high-temperature metastable phase; it transforms (back transition) into {alpha}-NiMoO{sub 4} at ca. 250 deg. C, while {beta}-NiMoO{sub 4} stabilised by a silica matrix does not.
- OSTI ID:
- 20888048
- Journal Information:
- Materials Research Bulletin, Vol. 39, Issue 4-5; Other Information: DOI: 10.1016/j.materresbull.2003.11.005; PII: S0025540803003635; Copyright (c) 2003 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0025-5408
- Country of Publication:
- United States
- Language:
- English
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