Nanotubes folded from cubic and orthorhombic SrZrO3: First-principles study

Hybrid functional of the density functional theory has been applied for investigations of the electronic and atomic structure of nanotubes (NTs) based on cubic and orthorhombic strontium zirconate. The full optimization of all atomic positions in the considered systems has been performed to study the atomic relaxation and to determine the most favourable nanostructures. The stability of the single-walled nanotubes of chiralities (n, 0) and (n, n) for the cubic, and (n1, 0) and (0, n2) for the orthorhombic SrZrO3 has been investigated in dependence on their diameter, the number of layers (2 or 4) in the slab, and the outer surface termination (SrO or ZrO2). The spontaneous splitting of the SrO-terminated (n, n) 4-layer nanotubes folded from the cubic phase into the two separated NTs has been found. The NTs folded from the orthorhombic phase, generally, preserve the atomic distortions inherent to the bulk SrZrO3 orthorhombic phases. However, the concrete NT surface structure depends on the chirality, the number of layers and termination type.