Synthesis of potassium hexatitanate whiskers using hydrothermal method

High quality potassium hexatitanate whiskers were hydrothermally synthesized in one step under moderate temperature and pressure conditions. Effects of the titanium source and reaction conditions on the hydrothermal reaction rate, product phase component, and morphology of whiskers were investigated. The results show that the reactivity of hydrated titania, anatase TiO2, and rutile TiO2 with KOH decreases in turn, and with hydrated titania as titanium source, it is difficult to obtain potassium hexatitanate whiskers with good morphology. In contrast, uniform potassium hexatitanate whiskers with a length of 10-20 μm and a diameter of 200-700 nm were obtained using anatase TiO2 as titanium source. The investigation demonstrates that the initial KOH concentration, annealing temperature and time, molar ratio of K2O/TiO2, etc. significantly affect the morphology of the as-synthesized whiskers. The optimized synthesis condition is as follows： anatase as a titanium source 10 wt.% KOH solution; annealing temperature and time of 300℃ and 5 h, respectively; K2O/TiO2 molar ratio of 5, etc. A rhombic potassium hexatitanate was prepared under the optimum condition and the whisker grew along the [110] direction. The reaction mechanism was discussed.

Molecular Dynamics Simulation of Rutile TiO_2 and Potassium Hexatitanate (K_3Ti_6O_(13)) Crystal

This paper presents the results of molecular dynamics (MD) simulation on the rutile titanium dioxide and potassium hexatitanate (K2O.6TiO2 or K2Ti6O13) crystal. The interaction of atoms is described by two-body central force interatomic potential, which includes Coulombic term, Gilbert-type repulsion term, van der Waals term and Morse-type potential. The optimized crystal structure of rutile TiO2 is in very good agreement with the experimental data in the literature. The present MD simulation also gives several physical properties, including volume thermal expansivity and elastic bulk modulus.

A HRTEM and XRD Study of the Potassium Hexatitanate Nanowires

The structure of potassium hexatitanate (K_2Ti_6O_13) nanowires has been investigated using both the Rietveld powder diffraction profile fitting technique and high resolution transmission electron microscopy (HRTEM) image simulations. From the Rietveld analysis it was shown that the nanowires had a monoclinic structure of the space group C2/M and the lattice parameters were a=1.5582 nm, 6=0.382 nm, c=0.9112 nm. HRTEM conclusions agree with refinement results obtained from experimental XRD data. The good agreement between the experimental and simulated images confirms that the nanowires is indeed K_2Ti_6O_13 nanowire.The growth axes of nanowires were mainly along the [010] direction.

ADSORPTION BEHAVIOR OF Pb(II) ON POTASSIUM HEXATITANATE WHISKER BY FAAS

Based on the advantage of high surface area and strong adsorption ability of potassium hexatitanate whisker, a method to determine trace Pb(II) content by combining solid phase extraction with Flame atomic absorption spectrometry (FAAS) was established. The adsorptive behavior of potassium hexatitanate whisker to Pb(II), primary influencing factors of adsorption and elution and effect of coexistence ions were investigated systemically. The optimal analytical conditions were discussed and examined. It was found that the adsorption rate of potassium hexatitanate whisker to Pb(II) was 100% at pH 4.0. Pb(II) could be eluted from potassium tetratitanate whisker with HCl (2mol/L) under boiling water for 30min. The detection limit was 5.75ng/mL, and relative standard deviation was 1.66% (n=9, CPb=2.0μg/mL).

Fabrication and properties of aluminum silicate fibrous materials with in situ synthesized K2Ti6O13 whiskers

To improve their mechanical and thermal insulation properties, aluminum silicate fibrous materials with in situ synthesized K_2Ti_6O_(13) whiskers were prepared by firing a mixture of short aluminum silicate fibers and gel powders obtained from a sol–gel process. During the preparation process, the fiber surface was coated with K_2Ti_6O_(13) whiskers after the fibers were subjected to a heat treatment carried out at various temperatures. The effects of process parameters on the microstructure, compressive strength, and thermal conductivity were analyzed systematically. The results show that higher treatment temperatures and longer treatment durations promoted the development of K_2Ti_6O_(13) whiskers on the surface of aluminum silicate fibers; in addition, the intersection structure between whiskers modulated the morphology and volume of the multi-aperture structure among fibers, substantially increasing the fibers' compressive strength and reducing their heat conduction and convective heat transfer at high temperatures.