Growth of YBa2Cu3Ox single crystals by a self-flux method with alkali chlorides as additives

Abstract Single crystals of YBa 2 Cu 3 O x in sizes up to 10 x 5 mm 2 in area and 50 μm in thickness have grown by a BaOCuO self-flux method with alkali chlorides MCl (M=Na, K, and Rb) as additives. T c of a crystal annealed in an oxygen atmosphere is determined magnetically to be 86 K. The X-ray diffractometry for the same sample, however, suggests the structure of orthorhombic-II featured by a lower T c . This discrepancy is probably explained by inhomogeneous oxidation which may divide the crystal into high T c- and low T c- parts. Added MCl is found to evaporate completely during soaking and to be absent when crystal growth is in progress. The role of MCl is presumably to remove impurities from the flux surface thus enhancing the crystal growth.