An All Sol-Gel Process for the Heteroepitaxial Growth of YBa2Cu3O7-x/LaNiO3/YBa2Cu3O7-x Tri-layer

The preparation of a YBa2Cu3O7 (x)/LaNiO3/YBa2Cu3O7-x sandwich structured film on a LaAlO3 (100) substrate by a sol-gel method was investigated. YBa2Cu3O7-x/LaNiO3/YBa2Cu3O7-x tri-layer heterostructures with different epitaxial characteristics can be deposited by controlling the heat treatment temperature. X-ray diffraction and transmission electron microscopy results show that the bottom YBCO film grows epitaxially on the LaAlO3 substrate along the c axis, and that this epitaxial growth trend is extended to the subsequently deposited LaNiO3 film. For this reason, the LaNiO3 film also grows epitaxially along the c axis. Furthermore, this epitaxial growth trend is extended to the top YBa2Cu3O7-x film, yielding YBa2Cu3O7-x/LaNiO3/YBa2Cu3O7-x tri-layer heterostructures with epitaxial growth characteristics along the c axis, which enables both the bottom and top YBa2Cu3O7-x layers to possess superconducting abilities.