For the samples sintered by CSP var

For the samples sintered by CSP varying the process temperature and the pellet dimensions (used in the optimization study, shown in the SI), an increase of the crystallite size is found as the temperature and pellet ratio increase, as reported in the SI (Figure S3). Specifically, for the CSP sample sintered at 110 ºC from 100 % MPs a crystallite size of ca. 97 nm is obtained displaying a slight growth of crystallite size even at the lowest CSP temperatures. The aqueous solution of acetic acid employed to sinter by CSP the ZnO facilitates the mass transport and the occurrence of the dissolution-precipitation processes, followed by a controlled evaporation of the aqueous solution that drives its supersaturation to allow the crystalline growth of ZnO grains. During this process, the influence of the pellet die sealing needs to be mentioned. The appropriated sealing conditions allow the aqueous solution to be trapped favoring the dynamic, but also the leakage of a certain fraction by evaporation or extrusion process from the imperfectly sealed pellet die.