Preparation of K_0.5Na_0.5NbO₃ thin film by the hydrothermal-assisted polymeric precursor method

The self-prepared niobium hydroxide, sodium carbonate, and potassium carbonate were used as raw material, citric acid (CA) and ethylene glycol (EG) were used as chelating agent and esterification agent separately. Potassium sodium niobate (KNN) thin films on SiO₂/Si substrates were prepared by the hydrothermal-assisted polymeric precursor method. The effects of the amount of CA and EG on the stability of the precursor Sol were investigated and the effects of Si slice and the annealed temperature on thin films were discussed. It was found that a homogeneous precursor Sol could be formed at the case of n (CA):n (metal ion) =3:1, n(CA):n(EG)=1:2. The crystallization and compact properties had been improved greatly when the Si slice was treated by hydrothermal method. With annealed temperature addition, the crystallization properties of thin films become better. The prepared thin films were uniformed in grain size, crack-free and grew directionally.