Abstract
Single-crystal TiO2(B) nanofibers were synthesized by the hydrothermal treatment in supercritical fluid at c.a. 375∼425°C under 23∼37 MPa using 10 mol·L-1 NaOH aq. followed by ion-exchange of Na to H in dilute HCl aq. and post-heating at 400°C in air. Thus prepared TiO2(B) nanofibers were characterized by XRD analysis, SEM/TEM observations, DTA/TG and BET surface area measurements. Electrical conductivity of the nanofibers and thermal conductivity of the nanofiber-compacts were also evaluated using "Nano-probe" and an Xenon flash measurement systems, respectively. Compared to the conventional TiO2(B) fibers prepared from the normal hydrothermal treatment at c.a.185°C for 8 h, the present TiO2(B) with several microns in length and 300∼400 nm in diameter, revealed higher thermal stability; TiO2(B) phase was stable even after heating at 800°C for 5 h in air, and an extreme high electrical conductivity of 1.2∼1.3 S·m-1 in addition to high thermal conductivity; the former and the latter were higher 1011 and 1.5 times than those of anatase TiO2 and normal TiO2(B).
