Surface modification of NiW alloy substrates for coated conductor

Because of the similarity of chemistry properties between sulfur and oxide,the c(2×2)-S ordered structure formatting on the surface of NiW substrates is conducive to control the texture types of the epitaxial oxide layers on the surface of metal Ni substrates.Most of the previous reports about c(2×2)-S superstructure on the surface of Ni substrates focused on the method which used H2S as the sulfur source,combining with the absorption and desorption to format this structure.A new technology route was put forward in this paper.(NH4)2S aqueous solution was used as the sulfur source and then heat treatment was taken to dislodge the disordered physical adsorption layers.The composition and structure of the sample surfaces treated by the new technology route were investigated by AES and RHEED.The results showed that notable amount of S element could be observed on the metal substrates treated by the new method and the c(2×2)-S superstructure was formatted on the surface of the substrates.The results of the buffer layers preparation on the surface with c(2×2)-S superstructure proved the effectiveness of the new sulfur method on improving the physical chemistry property of the surface of NiW substrates and epitaxial growth of the oxide layers.