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Title: Microwave-hydrothermal process for the synthesis of rutile

Abstract

The synthesis of pure rutile titanium dioxide is not an easy achievement, as the crystallization process generally leads to mixtures of two or even three phases; moreover the synthetic processes normally used by industry require harsh reaction conditions. We carried out the synthesis of titanium dioxide from an aqueous titanium tetrachloride solution under microwave irradiation in the reaction time range of 5-120 min. We mostly obtained mixtures of rutile and anatase, but obtained single-phase rutile after a 2-h treatment at 160 deg. C; transmission electron micrographs revealed well-dispersed spherical nanoparticles. We also investigated the effects of dilution and addition of a dispersant (polyvinylpyrrolidone) on phase crystallization and particle shape.

Authors:
 [1];  [2];  [1];  [1]
  1. Di.Sci.Far., Viale Benedetto XV, 3, University of Genoa, 16132 Genoa (Italy)
  2. Materials Research Institute, Pennsylvania State University, University Park, PA 16802 (United States). E-mail: komarneni@psu.edu
Publication Date:
OSTI Identifier:
20888114
Resource Type:
Journal Article
Resource Relation:
Journal Name: Materials Research Bulletin; Journal Volume: 40; Journal Issue: 11; Other Information: DOI: 10.1016/j.materresbull.2005.05.023; PII: S0025-5408(05)00208-4; Copyright (c) 2005 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; CERAMICS; CHEMICAL PREPARATION; CRYSTALLIZATION; IRRADIATION; MICROWAVE RADIATION; NANOSTRUCTURES; PVP; RUTILE; TITANIUM CHLORIDES; TITANIUM OXIDES; X-RAY DIFFRACTION

Citation Formats

Baldassari, Sara, Komarneni, Sridhar, Mariani, Emilia, and Villa, Carla. Microwave-hydrothermal process for the synthesis of rutile. United States: N. p., 2005. Web. doi:10.1016/j.materresbull.2005.05.023.
Baldassari, Sara, Komarneni, Sridhar, Mariani, Emilia, & Villa, Carla. Microwave-hydrothermal process for the synthesis of rutile. United States. doi:10.1016/j.materresbull.2005.05.023.
Baldassari, Sara, Komarneni, Sridhar, Mariani, Emilia, and Villa, Carla. Thu . "Microwave-hydrothermal process for the synthesis of rutile". United States. doi:10.1016/j.materresbull.2005.05.023.
@article{osti_20888114,
title = {Microwave-hydrothermal process for the synthesis of rutile},
author = {Baldassari, Sara and Komarneni, Sridhar and Mariani, Emilia and Villa, Carla},
abstractNote = {The synthesis of pure rutile titanium dioxide is not an easy achievement, as the crystallization process generally leads to mixtures of two or even three phases; moreover the synthetic processes normally used by industry require harsh reaction conditions. We carried out the synthesis of titanium dioxide from an aqueous titanium tetrachloride solution under microwave irradiation in the reaction time range of 5-120 min. We mostly obtained mixtures of rutile and anatase, but obtained single-phase rutile after a 2-h treatment at 160 deg. C; transmission electron micrographs revealed well-dispersed spherical nanoparticles. We also investigated the effects of dilution and addition of a dispersant (polyvinylpyrrolidone) on phase crystallization and particle shape.},
doi = {10.1016/j.materresbull.2005.05.023},
journal = {Materials Research Bulletin},
number = 11,
volume = 40,
place = {United States},
year = {Thu Nov 03 00:00:00 EST 2005},
month = {Thu Nov 03 00:00:00 EST 2005}
}
  • Uniform nanoparticles of rutile and anatase were prepared, respectively, by a new approach, a microemulsion-mediated method, in which the microemulsion medium was further treated by hydrothermal reaction. Herein, the combined procedure of microemulsion and hydrothermal synthesis to prepare nanoparticles is referred to as a microemulsion-mediated hydrothermal (MMH) method. This MMH method could lead to the formation of crystalline titania powders under much milder reaction conditions than the normally reported microemulsion-mediated methods, in which posttreatment of calcination was necessary. In this work, a kind of solution was formed by dissolving tetrabutyl titanate into hydrochloric acid or nitric acid, and the solutionmore » was dispersed in an organic phase for the preparation of the microemulsion medium. The aqueous cores of water/Triton X-100/hexanol/cyclohexane microemulsions were used as constrained microreactors for a controlled growth of titania particles under hydrothermal conditions. The product of hydrothermal synthesis was separated and dried for characterization. The phase components and the morphologies and grain sizes of products were determined by X-ray diffraction (XRD) and by transmission electron microscopy (TEM). The effects of changing the variables of the reaction conditions, such as the use of acid, the concentrations of acid, the reaction temperatures, and/or the reaction times on the phases and morphologies of the titania product are described.« less
  • In this paper, a simple and efficient methodology for the low-temperature synthesis of phase-pure nanocrystalline rutile TiO{sub 2} with tuned morphology is reported. Control on morphology has been achieved by simple variation of the hydrothermal process, starting with titanium-tetrachloride without using mineralizers, additives or templating agents. The X-ray diffraction (XRD) and selected area electron diffraction (SAED) patterns showed no other phases of TiO{sub 2} establishing the formation of phase-pure rutile titania in the entire temperature range of synthesis (40-150 deg. C) and most noticeably even at a considerably low temperature (40 deg. C). Fourier transform infrared (FT-IR) spectra strongly indicatedmore » the presence of hydroxyl group or surface adsorbed water and the thermogravimetry and differential thermo-gravimetry (TG-DTG) showed no phase change up to 1000 deg. C. A combination of reaction parameters (temperature, time) with a thorough transmission electron microscopy (TEM) study demonstrated the formation of phase-pure rutile titania nanocrystals as nano-rods, bunched nano-spindles or spherical nanoparticles depending on the hydrothermal reaction conditions. The photocatalytic activity of the synthesized nanocrystals has been successfully evaluated on the photodegradation of methyl orange (MO), a well-known pollutant azo-dye, as a model reaction.« less
  • Pure rutile phase titanium oxides (TiO{sub 2}) nanocrystals were synthesized via hydrothermal method with titanium tetrachloride (TiCl{sub 4}) and water (H{sub 2}O) treated in an autoclave. The particle size and phase assemblages were characterized using Scanning electron microscopy (SEM) and X-ray diffraction (XRD) respectively. Band gap energy (E{sub g}) of the nanocrystals was estimated from the Ultra violet – visible light (UV-vis) absorption spectra. It was demonstrated that TiO{sub 2} nanocrystals can be prepared through increasing of temperature and period of treatment. It is believed that the presence of acid chloride (HCl) as by-product during the hydrolysis played an importantmore » role in controlling the growth of morphology and crystal structures. The E{sub g} of the samples were estimated from the plot of modified Kubelka-Munk function were in the range of 3.04 – 3.26eV for the samples synthesized at temperature ranging from 50 to 200°C for 16 hours.« less
  • Rutile TiO{sub 2} nanorod arrays (TNRs) were achieved by hydrothermal process on TiCl{sub 4} pretreated Ti foil. Subsequently, TNRs were hydrothermally etched in HCl solution to form hollow TiO{sub 2} nanorod arrays (H-TNRs). The TiCl{sub 4} pretreatment plays key roles in enhancement of Ti foil corrosion resistance ability and crystal nucleation introduction for TNRs growth. TNRs with desired morphology can be obtained by controlling TiCl{sub 4} concentration and the amount of tetrabutyl titanate (TTB) accordingly. TNRs with the length of ∼1.5 μm and diameter of ∼200 nm, obtained on 0.15 M TiCl{sub 4} pretreated Ti foil with 0.6 mL TTB,more » exhibits relatively higher photocurrent. The increased pore volume of the H-TNRs has contributed to the increased surface area which is benefit for Dye-Sensitized Solar Cells (DSSC) application. And the 180 °C-H-TNRs photoanode obtained from the 0.15-TiCl{sub 4}-TNRs sample demonstrated 128.9% enhancement of photoelectric efficiency of DSSC compared to that of the original TNR photoanode. - Graphical abstract: Rutile hollow TiO{sub 2} nanorod array photoanode obtained from original TiO{sub 2} nanorod array photoanode by hydrothermal etching demonstrates enhanced photoelectric efficiency of DSSC. - Highlights: • TiO{sub 2} nanorods are prepared via hydrothermal process on TiCl{sub 4}-pretreated Ti foil. • Hollow TiO{sub 2} nanorods are obtained by hydrothermal etching of TiO{sub 2} nanorods. • TiCl{sub 4} pretreatment plays a key role in protecting Ti foil from chemical corrosion. • Hollow TiO{sub 2} nanorods photoanode shows enhanced photoelectric efficiency for DSSC.« less
  • Nanocrystalline ceria powders (CeO{sub 2}) have been prepared by adding NaOH to a cerium ammonium nitrate aqueous solution under microwave-hydrothermal conditions. In particular the effect of the synthesis conditions (time, pressure and concentration of both the precursor and the precipitant agent solutions) on the physical properties of the crystals have been evaluated. Microwave-hydrothermal treatment of 5 min at 13.4 atm allows to obtain almost crystallized powders (amorphous phase 4%) as underlined by Rietveld-reference intensity ratio (RIR) results.