Effects of Pyrolysis Temperature on Structural, Raman, and Infrared Properties of Perovskite PbTiO3 Nanotubes

In this work, we investigated the effects of the pyrolysis temperature on the structural, Raman, and infrared properties of PbTiO3 nanotubes (PTO-NTs). The PTO-NTs were synthesized by spin coating a sol-gel solution on porous anodic alumina membranes, followed by the pyrolysis step at 400 -600 degrees C. Then, PTO-NTs were finally crystallized at 600 - 700 degrees C in an oxygen atmosphere to get the perovskite phase. The PTO-NTs had an outer diameter of about 420 nm and a wall thickness of about 10 nm. X-ray diffraction patterns showed that the tetragonality (c/a) increased from 1.019 to 1.028 as the pyrolysis temperature was increased from 400 to 600 degrees C. Raman spectroscopy showed that the phonon modes of A(1)(nTO) and E(nTO) increased with a redshift of the A(1)(3TO) mode as the pyrolysis temperature was increased. In the Fourier-transform infrared spectra of PTO-NTs embedded in the porous anodic alumina membrane, the transmittance of the band at 499 cm(-1) increased as the pyrolysis temperature was increased, which might be due to an increase in the tetragonality.