Processing–structure–property of nanocrystalline materials produced using novel and cost-effective ESAVD-based methods

This paper presents an overview of the emerging cost-effective Electrostatic Spray-Assisted Vapour Deposition (ESAVD)-based methods for the synthesis of nanocrystalline oxide and non-oxide ceramic films and powders. The ESAVD process involves spraying atomised precursor droplets across an electric field. If the processing conditions are tailored such that the droplets undergo heterogeneous chemical reaction near the vicinity of the heated substrate, this produces a stable solid film with excellent adhesion onto a substrate in single production run. This is an atomistic deposition method, which can produce highly pure materials with structural control at the nanometer-scale level at low processing temperatures. The structure, stoichiometry, crystallinity and texture can be controlled by optimising the deposition conditions. Powders can be produced by tailoring the homogeneous gas phase reactions to occur during the deposition. The deposition mechanism of the ESAVD process will be presented. The scientific and technological significance of the ESAVD-based methods to produce nanostructured films and powders of oxide (e.g., Y2O3:Eu, TiO2) and non-oxide (ZnS and CdS) materials will be likewise presented. The processing–structure–property relationships of the deposited materials will be discussed. The benefits of ESAVD will be highlighted and compared with other processing techniques.