The CSP is a sintering route in whi

The CSP is a sintering route in which a large number of process parameters can be evaluated and optimized [4,8], which is an advantage both for densifying materials in a controlled way and tailoring the final properties of the sintered pieces. Here, an investigation on the incorporation of ZnO in its nano form into micro powders and its effect on the densification of the cold sintered ZnO samples is followed. A first study on both the optimal annealing temperature and the dimension ratio of the ceramic pieces is performed (see Figure S1 in SI). Significant modifications depending on the CSP temperature are found: an increase of the relative density from 67 % for the sample prepared at 110ºC to relative density values around 95 % at processing temperatures of 170 ºC -190 ºC, densifying the ZnO ceramics at temperatures well below those used in the CN process in accordance with previously reported experiments [12,16]. On the other hand, fixing the CSP processing temperature to 170 ºC, as the lowest temperature required to densify ZnO ceramics, relative density values close to 95 % are obtained for height/diameter ratio of pellets ≥ 0.38.