Morphology-Tuned Phase Transitions of Horseshoe Shaped BaTiO₃ Nanomaterials under High Pressure

Exploring new physical properties of nanomaterials with special morphology have been important topics in nanoscience and nanotechnology. Here we report a morphology-tuned structural phase transition under high pressure in the horseshoe shaped BaTiO₃ nanomaterials with an average diameter of 26 ± 4 nm. A direct structural phase transition from the tetragonal to the cubic phase without local rhombohedral distortion was observed at about 7.7 GPa by in situ high-pressure X-ray diffraction and Raman spectroscopy, which is clearly different from the phase transition processes of the BaTiO₃ bulks and nanoparticles. Additionally, bulk modulus of the tetragonal and cubic phases were determined to be 125.0 and 211.7 GPa, respectively, obviously smaller than the estimated values for BaTiO₃ nanoparticles with the same grain size. Further analysis shows that the unique phase transition process and the enhanced structural stability of the tetragonal horseshoe shaped BaTiO₃ nanomaterials, may be attributed to the similar axes compressibility. Comparing with the high-pressure study on BaTiO₃ nanoparticles, this study suggests that the morphology plays an important role in the pressure-induced phase transition of BaTiO₃ nanomaterials