Effect of vanadium ion implantation on the crystallization kinetics and phase transformation of electrospun TiO<inf>2</inf> nanofibers

Abstract

© 2015, Springer-Verlag Berlin Heidelberg. The influence of V ion implantation on the thermal response of electrospun amorphous TiO<inf>2</inf> nanofibers was studied with reference to structural phase transformation behavior, using in situ synchrotron radiation diffraction (SRD) measurements from room temperature to 1000 °C. Analysis of the SRD data provided activation energies for amorphous-to-crystalline TiO<inf>2</inf> (anatase and rutile) and anatase-to-rutile transformations, and also assessments of the influence of V ion implantation on microstructure development during calcination using estimates of crystallite size and microstrain. Non-implanted nanofibers were initially amorphous, with crystalline anatase first appearing at 600 °C, followed by rutile at 700 °C. The corresponding activation energies were 69(17) kJ/mol for the amorphous-to-crystalline TiO<inf>2</inf> transformation and 129(5) kJ/mol for the anatase-to-rutile transformation. V ion implantation resulted in a lowering of the temperature at which each crystalline phase first appeared, with both phases being initially observed at 500 °C and with the anatase-to-rutile transformation being accelerated relative to the non-implanted sample. The effect of V ion implantation is seen through the substantial reduction in activation energies, which are 25(3) kJ/mol for amorphous-to-crystalline TiO<inf>2</inf> and 16(3) kJ/mol for anatase-to-rutile transformations.