BaMO₃(M = Zr, Hf) Doped REBCO Tapes Fabricated by Fluorine-Free MOD

Using a low-cost fluorine-free metal organic decomposition (FF-MOD) method, REBCO films with BaMO₃ (BMO, M = Zr, Hf) artificial pinning centers were fabricated. When M elements are conventionally added to the solution, the size of BMO formation depends on the growth conditions. But by adding preformed BMO nanoparticles, the size can be maintained on the nanometer order, meaning the nanoparticles act as effective pinning centers at low temperatures and magnetic fields. Adopting a polycrystallization sintering process enables the BaCO3 to decompose completely and polycrystalline REBCO films to form prior to REBCO orientation. After final sintering, REBCO orientation can be achieved over a wide temperature range even with the addition of BMO nanoparticles. By utilizing preformed BMO nanoparticles and a polycrystallization sintering process, BMO doped GdBCO over 100 m-long tapes which have a thickness of more than 3 μm can be achieved. This is the first report of 120-meter-long artificial pinned REBCO tapes with Ic exceeding 200 A/4 mm width at 77 K, self-field made by the FF-MOD method.