Fabrication and characterization of dielectric nanocube self-assembled structures

Orderly assemblies of BaTiO ₃ (BT) cube-shaped nanocrystals (nanocubes) and BT-SrTiO ₃ (ST) mixture nanocubes were fabricated on Pt-coated Si substrates directly by capillary-force-assisted solution self-assembly and heat treatment. These dielectric nanocubes aligned face to face in quite a wide region of 10 × 50 μm2 on the average with a height of 1 μm. The local microstructure of the nanocube assembly was observed by high-resolution transmission electron microscopy. It was revealed that the lattice strain at the interface of the neighboring nanocubes was locally induced. The piezoresponse of the BT-ST mixture nanocube assembly showed a nonlinear curve and a stepwise behavior at a high poling field, which differed from the ferroelectric BT and paraelectric ST assemblies investigated by scanning probe microscopy. The characteristic behavior might be attributed to the interfacial lattice strain in mixture assemblies.