Nowadays, researches have been dire

Nowadays, researches have been directed towards materials that possess high performance at low cost and limited environmental impact, since awareness of carbon dioxide emissions and global warming has increased [7, 8]. Therefore, sintering processes are being driven by these challenges that motivate research into environmentally friendly technologies inspired by natural phenomena [7, 9-11]. These studies found a relationship between pressure and heating for consolidation ceramics using water as a densification enhancing agent. In this context, an innovative energy-saving technology was developed in 2016 called cold sintering process (CSP), which operates in an open system under non-equilibrium conditions [9-12]. Various paths have been adopted to obtain dense ceramics at low temperature using CSP depending on the chemistry of materials and transient solvents [9, 13]. In materials with high water solubility, CSP is easily implemented as a dissolution/precipitation process, and thus densification directly occurs due to congruent dissolution [9]. For materials showing negligible dissolution, CSP takes place via surface reaction through selecting the appropriate solvent to allow high ionic exchanges on particle surfaces [9, 14, 15]. However, materials with incongruent dissolution show the appearance of a passive layer appears on particle surfaces, which prevents the dissolution or reaction/precipitation process [9, 11, 16]. Therefore, a saturated solution that produces amorphous or intermediate phases around the particles after evaporation must be introduced. These phases are then transformed into the required crystalline phase by heat treatment. In the case that attention should be given to electronic properties rather than mechanical properties, a chemical active solvent such as water-soluble salts was used to obtain fully dense ceramic in a single densification step [11, 13]. Another promising route is the use of a water-containing precursor such as hydroxides, which are then converted to the wanted oxide after heat treatment [7, 13, 17].