Recent activities in the R&D of coated conductors are reviewed. Coated conductors were classified into two groups based on the architecture. One group is textured metal substrates such as RABiTS. In this group, a high performance of Ic=186 A/cmw in a 34 m-long tape was realized using a TFA-MOD process with several PVD buffer layers. Remarkable results have also been reported by the other R&D group, which uses IBAD buffered substrates. Combined with the PLD method for the YBCO layer, the highest values of Ic·L have been obtained. The highest Ic·L value is 13230 Am by Fujikura. Aiming at lower processing costs, TFA-MOD and MOCVD processes have also been investigated using IBAD substrates. SRL achieved an extremely high Ic value of 413 A/cm-w in a tape produced using the TFA-MOD process. R&D efforts in long tape processing have led to a 8.6 m-long tape with 119 A/cm-w as the Ic value.
In order to shorten the calcination time in the metal-organic deposition (MOD) process using metal trifluoroacetate (TFA), a new combination of starting materials was developed using the F-free salt of Cu and TFA salts of Y and Ba as a so-called "new solution". Moreover, a new process temperature profile for this solution was developed as an advanced TFA-MOD process in which a high heating rate was achieved. Consequently, an overall transport Ic value of 210 A and a Jc value of 1.5 MA/cm2 (77 K, Self-field), similar to Ic and Jc values using TFA for all salts, were obtained. In order to obtain higher Jc performance, the effects of process parameters such as the heating rate in the calcination process for the Jc characteristics were investigated. As a result, a YBCO film with a thickness of 1.2μm was fabricated on a CeO2/IBAD-Gd2Zr2O7 layer-buffered Hastelloy substrate with Δφ∼7°. The overall Ic value of 251 A (77 K Self-field) corresponding to the Jc value of 2.1 MA/cm2 was achieved by calcination at a heating rate of 2°C/min.