The crystallization process of HfO2 and ZrO2 under hydrothermal conditions

Fast and Tunable Synthesis of ZrO2 Nanocrystals: Mechanistic Insights into Precursor Dependence

“…16,42 Water is believed to increase the solubility of the formed ZrO2 precipitates during synthesis which facilitates the effective operation of dissolution and precipitation leading to the more stable m-ZrO2. 16,[43][44][45] To assess the role of water in in our synthesis method, distilled water was added to the propoxide precursor. From the resulting XRD and TEM analysis it is clear that the presence of water does not lead to a change in crystal phase of ZrO2 (Table 3, Figure 4 and SAED Figure 5B).…”

Fast, microwave-assisted synthesis of monodisperse HfO2 nanoparticles

“…Even the use in biological applications should not be excluded because of the negligible cytotoxicity of HfO2 (Field et al 2011). Hafnium oxide nanoparticles have already been synthesized with a variety of methods, such as surfactant based (Dahal and Chikan 2012;Tang et al 2004;Chaubey et al 2012;Tirosh and Markovich 2007), hydrothermal (Stefanic et al 2005), microwave assisted hydrothermal (Eliziario et al 2009), ultrasonically assisted hydrothermal (Meskin et al 2007), solvothermal (Pinna et al 2004;Pucci et al 2009;Boyle et al 2012;Buha et al 2010), precipitation ) and sonochemical synthesis . However, most of these methods are unfavorable because of a long reaction time, a broad size distribution, the agglomerated state of the particles or the large diameter.…”

Ball milling assisted hydrothermal synthesis of ZrO2 nanopowders

“…3 and 7), tetragonal phase forms in addition to monoclinic phase. This difference results from different starting materials (i.e., solution versus aqueous gel) because in situ crystallization of amorphous aqueous zirconia proceeds via a dissolution-precipitation process rather than a topotactic crystallization (e.g., structural rearrangement of amorphous hydrous zirconia), and nanocrystalline monoclinic (m), tetragonal (t) and cubic (c) ZrO 2 phases form practically simultaneously during hydrothermal treatment of zirconia gel depending on the hydrothermal conditions, particularly pH [6,14,17,18]. Denkewicz et al [18] reported that crystallization takes place by an in situ topotactic process in a neutral or mild acidic medium due to low solubility, which facilitates predominantly t-ZrO 2 formation.…”