Structure and orientation of a superconducting Y-Ba-Cu-O thin film on zirconia substrate. A study by micro-Raman spectroscopy

A thin film of YBa 2Cu 3O x deposited on Zirconia (100) substrate, and transiting at 92 K was examined by micro-Raman spectroscopy. The layer is revealed to be an aggregation of two types of micro-crystals: one of them is oriented with the c axis nearly perpendicular to the surface and having often truncatures which give them the appearance of nearly square pyramids, and the others with the c axis parallel to the surface. The oxygen content is evaluated to be x = 6.97, therefore the formula of the superconducting material could be YBa 2Cu 3O 7. This oxygen amount is relatively homogeneous at various areas on the surface even where the distribution of the crystal aggregate is not homogeneous. After six months, a lost of oxygen, down to x = 6.8 in the same sample is recorded. These micro-crystals appear to grow on a continuous ground which was identified as a green phase, Y 2BaCuO 5 resulting from the interaction at the interface between YBa 2Cu 3O 7 and the substrate dopped itself with Y 2O 3.