Effect of precursor solution pH on the structural and crystallization characteristics of sol–gel derived nanoparticles

Abstract

This paper concerns with the effect of pH on the structure and crystallization behavior of particulate sol–gel derived zirconium titanate. According to differential scanning calorimetry, it was found that the thermal stability of the synthesized amorphous particles was enhanced by increasing the precursor solution pH value from 4 to 10, as confirmed by X-ray diffraction. Transmission electron microscopy studies on the xerogel and crystallized nanoparticles showed that the pH value does not fairly affect their size and morphology; thus, these structural features cannot have a meaningful contribution to the detected crystallization difference. The realized thermal behavior was explained based on a mechanism relating to the adsorption of hydroxide ions (OH−) existing in the medium to metallic hydroxide precipitates synthesized during the sol–gel process. In this regard, it was speculated that the more the pH value is increased, as reasonably accompanied by the more hydroxide adsorption, the more the crystallization event is inhibited.