Hydrolysis of Titanium(IV) Sulfate Solutions under Hydrothermal Conditions

The structure and the phase, granulometric, and chemical composition of hydrated titanium dioxide obtained by hydrolysis of oxotitanium(IV) sulfate and ammonium titanium(IV) oxysulfate solutions under hydrothermal conditions (130-170°C) were studied by X-ray and chemical analyses, electron microscopy, and thermogravimetry. The effect of hydrolysis conditions on the formation of samples with globular shape of particles was studied.     

Phase Formation in the System FeOOH-Zn(OH)2-H2O under Hydrothermal Conditions

Sequence of chemical transformations occurring in the system FeOOH-Zn(OH)₂-H₂O in the course of heat treatment at 125-200°C was studied by X-ray phase analysis, electron microscopy, and chemical analysis.     

Crystallochemical Aspect of Phase Formation in the γ-FeOOH-H2O-NaOH System

Phase transition of metastable -FeOOH into -FeOOH and its chemical transformation into -Fe₂O₃ upon hydrothermal treatment in 0-5 M NaOH solutions at 100-230°C were studied. The regions of formation of the above phases were specified. The probable composition of the crystallizing complexes formed in the solutions and the reactions occurring at their incorporation into various atomically smooth faces of -FeOOH and -Fe₂O₃ were considered.     

Thermal Transformations of Hydrated Titanium Dioxide with a Globular Structure of Aggregates

The phase and chemical transformations in hydrated titanium dioxide with a globular structure of aggregates, prepared by thermal hydrolysis of aqueous solution of oxotitanium(IV) sulfate and calcined in air at 200-1100°C, were studied. The effect of modifying additives (potassium, zinc, magnesium, and phosphorus compounds) and seed crystals of rutile-like structure on the kinetics and temperature of the polymorphous transition of anatase into rutile, morphology of crystals, and particle size of the resulting product was studied.     

Effect of Synthesis Parameters on the Phase Formation in the System FeSO4-H2O-H+/OH--O2 (3.5 ≤ pH ≤ 13)

Regular trends in the phase formation in the course of oxidation of aqueous FeSO₄ solutions and(or) Fe(OH)₂ suspensions under steady-state conditions (pH₀ = const, T = const) with atmospheric oxygen were studied within broad ranges of pH, temperature, total concentration c ⁰Fe(II), and air space velocity.     

Effects of Mechanochemical Activation and α-Fe2O3 Addition on the Formation of Corundum in Thermal Transformations of γ-Al(OH)3

Transformations of hydrargillite -Al(OH)₃ during mechanochemical activation in various grinding mills and further calcination of activated samples at 200-1300°C were studied. The effects of mechano-chemical activation and additions of iron(III) oxide compounds on the temperature of corundum formation and on its crystal size distribution were studied.