Precise tuning of (YBa₂Cu₃O_7-δ) _1-x:(BaZrO₃)_x Thin film nanocomposite structures

Self-assembled nanocomposite films and coatings have huge potential for many functional and structural applications. However, control and manipulation of the nanostructures is still at very early stage. Here, guidelines are established for manipulating the types of composite structures that can be achieved. In order to do this, a well studied (YBa₂Cu ₃O_7-δ)_1-x:(BaZrO₃) _x 'model' system is used. A switch from BaZrO₃ nanorods in YBa₂Cu₃O_7-δ matrix to planar, horizontal layered plates is found with increasing x, with a transitional cross-ply structure forming between these states at x = 0.4. The switch is related to a release in strain energy which builds up in the YBa₂Cu ₃O_7-δ with increasing x. At x = 0.5, an unusually low strain state is observed in the planar composite structure, which is postulated to arise from a pseudo-spinodal mechanism.