Assessment of the Role of Speciation during Cold Sintering of ZnO Using Chelates

Cold sintering (CS) is a chemically driven densification technique enabling a substantial decrease in the sintering temperature of oxides, by several hundreds of degrees Celsius. Although the densification process in CS is known to be mainly driven by pressure solution creep, additional fundamental aspects driving the interfacial chemistry reactions are still a subject of debate. Herein, we focus on the aspect of speciation in the densification process. The densification of zinc oxide (ZnO) by CS using zinc acetylacetonate hydrate (Zn(acac)2·xH2O), a versatile ligand often used as a precursor for ZnO synthesis in wet chemistry, is reported. The successful densification of ZnO using H2O and Zn(acac)2·xH2O confirms the importance of speciation in CS, as ZnO has a very low solubility in pure H2O. The evolution of the system at different stages of sintering and the role of the Zn(acac)2·xH2O species were evaluated.