Hydrochemical synthesis of Ga-doped ZnO conductive powder through in-situ transformation of ε-Zn(OH)2 or ZnGa-LDH

Ga-doped zinc oxide (GZO) has attracted considerable interest for applications in electronic transport owing to its superior electrical properties. In this study, we report a low-temperature (<100°C) aqueous open-system route for the in-situ synthesis of GZO powders. The efficient substitutional doping of Ga 3+ into the ZnO lattice is achieved via a formation, in-situ transformation and dissolution–reprecipitation pathway of ε-Zn(OH) 2 or ZnGa-layered double hydroxide (ZnGa-LDH) intermediates, which simultaneously endows the products with unique flower-like or bundle-like morphologies. Chemical equilibrium calculations and time-dependent experiments reveal that the ionic species Zn(NH 3 ) 4 2+ and Ga(OH) 4 - , formed in the aqueous solution under high ammonia concentration, serve as reactive monomers that facilitate the formation and transformation of the intermediate phases. Electrical measurements combined with UV-Vis-NIR, EPR, and PL spectroscopic analyses indicate that Ga doping introduces shallow donor-type defects alongside zinc vacancy-related acceptor defects into the ZnO lattice, narrowing the optical bandgap and enhancing the electrical conductivity of the resulting powders. The GZO powder with a nominal doping ratio of 5% exhibits the lowest resistivity (Surface resistivity measured by the four-probe method is 3.43 × 10 4  Ω/□). This work provides a new pathway for the controllable preparation of functional conductive oxide powders.