Structure Determination and Compositional Modification of Body-Centered Tetragonal PX-Phase Lead Titanate

The fibrous PX-phase of lead titanate (PT), which can be synthesized by a hydrothermal method, has been studied to clarify its structural aspects on the atomic level. By combining synchrotron X-ray diffraction and electron microscope analysis with a first-principles calculation, a unique open-channel structure with a 5.529 angstrom diameter bore through the whole wire is determined. First-principle modeling reveals that the PX-phase structure has an indirect wide band gap and a higher formation enthalpy than the tetragonal perovskite phase. Both the frequency and symmetry of Raman-active lattice vibrational modes have been identified with polarized Raman spectra on individual monocrystalline PX-phase PT wires, showing a good match with the first-principles calculation. Furthermore, the doping of Zr in the PX-phase PT and the influence on the structure were investigated, showing a limit of 17% incorporation of Zr in the PX-phase PT.