Tunable morphology of strontium titanate nanocubes controlled by tert-butylamine-assisted solvothermal method and their enhanced electrical conductivity

Abstract

The exploration of the size and shape of well-defined strontium titanate (SrTiO3) nanocubes remains challenging despite the increasing interest in this material, owing to its remarkable morphology-dependent electron and phonon transport abilities. This paper discusses the controllable solvothermal synthesis of SrTiO3 nanocube with tunable morphology in the ethanol-water solvent, using cetyltrimethylammonium bromide (CTAB) as a capping agent and tert-butylamine (TBA) as a mineralizer. The SrTiO3 nanocubes crystallization can be described as the dissolution-precipitation process, and the addition of CTAB and TBA affects the transformation of oriented attachment in forming a well-defined nanocube. In this study, the X-Ray Diffraction (XRD) data supported by the Le Bail refinement analysis revealed the shape-dependent tuning in lattice parameters of polycrystalline samples. The electrostatic interaction of CTAB and TBA on the particle surface of SrTiO3 was proven by the appearance of specific absorption peaks in the IR spectrum. XPS spectra show the chemical shift toward higher binding energy confirming the attraction of the nitrogen N-containing groups from CTAB and TBA with SrTiO3 through the synergistic capping effect. Meanwhile, HRTEM images showed that the nanocube particles have a uniform shape, sharp edges and vertices, flat faces, and narrow size distribution. In addition, the electrical conductivity in the bulk samples with uniform nanocubes increases three-fold compared to non-uniform nanocubes. These findings can potentially set a foundation for establishing synthesis techniques for producing morphologically-distinct particles based on surface interactions through the selective adsorption of additives.