Calcination effects on the properties of Gallium-doped zinc oxide powders

Highly conductive Gallium-doped zinc oxide (Zn_1-xGa _xO) powder was prepared by calcining precursor that was synthesized from ZnSO₄ · 7H₂O, GaCl₃, and NH ₄HCO₃ by the coprecipitation method. The effects of temperature, heating time, and atmosphere on the calcination process were studied, and we found that these factors are important to control the electrical conductivity, particle size, and agglomeration of Zn_1-xGa _xO powder. By studying these processing conditions, we found that the optimum one is calcining the precursor in H₂ at 540°C for about 1.5 h, and the product has a specific surface area higher than 28 m ²/g and volume resistivity lower than 16.8 Ω · cm. The chemistry details of the doping process were also discussed based on the experimental results.