Controllable hydrothermal synthesis of KTa1-xNbxO3 nanostructures with various morphologies and their growth mechanisms

Various single-crystalline nanostructures of potassium tantalite-niobate (KTa1-xNbxO3, KTN) were synthesized by a hydrothermal method at 200 degrees C. Interesting structures including KTaO3 nano-octahedrons, KTa0.5Nb0.5O3, KTa0.35Nb0.65O3, and KTa0.77Nb0.23O3 nanocubes, KTa0.25Nb0.75O3 tower-like nanostructures, and KNbO3 truncated octahedrons were obtained. The amount of KOH and polyethylene glycol (PEG) is crucial for the formation of pure phase KTa1-xNbxO3 with specific morphologies. The dissolution-precipitation growth mechanism should be accountable for the formation of perfect KTN cubes, and the competition between the supersaturation ratio and the surface energies of nanoclusters may react to the growth of octahedron and truncated octahedron KTN. The experimental results show that the formation of high-quality single-crystalline KTN with tower-like nanostructures may be ascribed to the oriented attachment mechanism.