Growth Characteristic of Scheelite BaWO4 Film by Using Electrochemical Technique at Room Temperature

Abstract

Barium tungstate (BaWO4) films were prepared directly on metal tungsten substrates at room temperature by using constant current electrochemical technique, and the growth characteristic of the films was investigated from the early stage to the terminal stage. The growth process of the films was characterized through SEM and EDX measurement. It was found that at the early stage of film growth, the substrates form W-O4 anion coordination polyhedra through electrochemical reaction, a quantity of WO4 anion coordination polyhedra deposit on the defects of the substrate and form the scheelite framework, then the Ba2 + ions fill in the framework resulting in the growth units, the favorable units grow up and form the crystalline nucleus and granules with the tetragonal pyramid structure; along with the extension of the deposition time, the WO4 anion coordination polyhedra deposit and the Ba2 + ions fill in from the middle to the two sides of the crystalline granules continually, finally, the crystalline granules with tetragonal bipyramid form become full and bestrew the whole tungsten substrate to form the compact BaWO4 films.