A sol-hydrothermal method has been proposed to prepare uniform and unaggregated nanocrystals of pure anatase and rutile from various acidic mediums. The phase formation, particle sizes, and morphologies varying with different acids and their concentrations at different reaction temperatures and times have been investigated using X-ray diffraction and transmission electron microscopy. The use of HCl and the effect of its concentrations on the formation of rutile phase at different temperatures for various reaction times have been described in detail. The effect of the addition of NaCl salt on particle sizes and rutile fractions has also been studied. In this work, the phase transformation from anatase to rutile in the presence of and the absence of NaCl salt has been considered both in neutral and in acidic mediums. The presence of a trace rutile in starting materials of anatase can show obvious effects on the phase transformation under hydrothermal conditions.

Hollow spheres of mesostructured lead titanate, denoted as PTM-1, have been prepared via a combined oil-in-water emulsion mediated and neutral amine supermolecular templated route. The variety of reaction temperatures and KOH concentrations indicates hollow spheres can be formed under a very critical condition. The structure and composition of the as-synthesized PTM-1 have been determined by powder X-ray diffraction, high-resolution transmission electron microscopy (HRTEM), energy-dispersive X-ray spectroscopy (EDS), CHN (carbon-hydrogen-nitrogen) elemental analysis, and thermal analysis. Chemical extraction of organic templates by a cosolvent of weak acid and alcohol has resulted in the formation of a new mesoporous material of non-silica oxide with high porosity.

Tetragonal BaTiO3 powders were prepared hydrothermally, using Ba(OH)2·8H2O and TiO2 (anatase), in the absence of anions such as chloride ions, at a temperature of 220°C for several days. Characterization via X‐ray diffractometry, scanning electron microscopy, and differential scanning calorimetry confirmed that increasing the Ba:Ti molar ratios (from 1:1 to 4:1) and alkaline concentrations (from 1.0M to 3.0M) promotes the formation of tetragonal BaTiO3.