Publications by authors named "Ali Kalaji"
Crystalline precipitates resulting from the hydrolysis and subsequent condensation of Hf(IV) aqueous acidic solutions at 60-95 °C are examined and compared. By varying the concentrations of the acid and sulfate source, a variety of complex hafnium-oxo-hydroxo-sulfate clusters are isolated and structures accessed. Four novel compounds were discovered, while the structures of two known compounds, an 18-mer and a planar hexamer, were updated.
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- The study investigates how the speciation of Hf(4+) in sulfate solutions relates to the structures of precipitates formed.
- High-energy X-ray scattering and Raman spectroscopy reveal that Hf(4+) forms significant clusters in acidic solutions rather than individual metal ions.
- The presence of sulfate alters the species in solution, breaking down larger clusters into smaller sulfate-capped dimers and single Hf-sulfate monomers, impacting the crystallization process and highlighting differences between Hf and Zr's aqueous behaviors.
Monolithic gels have been produced by reaction of Si(NHMe)(4) with ammonia in THF solution and converted to high surface area aerogels by critical point drying with ammonia saturated diethylamine solvent.
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