“…The YBa [13,14]. Y 2 O 3 , CaCO 3 , Ba 2 CO 3 , SrCO 3 and CuO powders were thoroughly mixed in the proportions 1:3.5:0.5:10 of Y, Ba, Sr and Cu respectively for YBa(Sr)CuO samples, and in proportions 0.95:0.05:4:10 of Y, Ca, Ba, Cu for Y(Ca)BaCuO samples.…”