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Figure 2. (A) Crystal structures of single-perovskite ABO3, e.g., BaZrO3 (BZO). (B) Crystal structures of double-perovskite A2BB’O6, e.g., Ba2YNbO6 (BYNO) and Ba2YTaO6 (BYTO). (C) Crystal structures of REBCO, e.g., YBCO and GDBCO[35] © 2017 IOP Publishing Ltd. Printed in the UK.