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Continuous-reactor, pH-controlled synthesis of multifunctional mesoporous nanocrystalline anatase aggregates

X-Ray Diffractometer (XRD) application in the research of the phase identification, crystal lattice structure and calculate crystal size
MIAM | 1 Apr 2016

Continuous-reactor, pH-controlled synthesis of multifunctional mesoporous nanocrystalline anatase aggregates

Research Published at:Ìý, , , 1 March 2016, Pages 398-409

Authors:ÌýBenedetto Marelli,† Chiara E. Ghezzi,† Jake E. Barralet,‡ Aldo R. Boccaccini,§ and Showan N. Nazhat*,†

  • Department of Mining and Materials Engineering, Faculty of Dentistry, Ï㽶ÊÓƵ,
  • Department of Materials Science and Engineering, University of Erlangen-Nuremberg, Germany

Research Method:

For phase identification, X-ray diffraction (XRD) was performed. scanning took place between 20° and 70° (2h) with 0.005°step/second. Background subtraction and smoothening were performed on EVA software. The XRD patterns were compared against JCPDS reference data of anatase (#00-021-1272). Crystallite size was determined using following Scherrer equation:

Dhkl = kλ/(β cosθ)

Where, Dhkl is crystal size in nm, k is 0.89, k is wavelength of Cu radiation (0.1549 nm), b is FWHM (Full Width at Half Maximum) corresponding to (hkl) plane in radians, and h is the Bragg angle corresponding to (hkl) plane in radians.

XRD research figÌý

Fig. 3.ÌýXRD patterns of TiO2Ìýproducts synthesized at: (a) 70Ìý°C, (b) 80Ìý°C, and (c) 90Ìý°C compared toÌýanataseÌýreference pattern. Constant conditions: [TiCl4]feedÌý=Ìý0.1ÌýM, pHsteady-stateÌý=Ìý3,ÌýÏ„: 30Ìýmin.

Rutile peak at 27.5° is evident. At pH 6 the product became amorphous.

XRD research fig 2

Fig. 4.ÌýXRD patterns of steady state products compared toÌýanataseÌýreference pattern: The effect of pH: (a) pH 2, (b) pH 3, (c) pH 4, (d) pH 5; constant conditions:ÌýTÌý=Ìý80Ìý°C, [TiCl4]feedÌý=Ìý0.1ÌýM,ÌýÏ„Ìý=Ìý30Ìýmin. The effect of [TiCl4]feed: (e) 0.1ÌýM, (f) 0.2ÌýM, (g) 0.3ÌýM, (h) 0.4ÌýM, (i) 0.5ÌýM; constant conditions:ÌýTÌý=Ìý80Ìý°C, pHsteady-stateÌý=Ìý3,ÌýÏ„Ìý=Ìý30Ìýmin.

Results:

  • XRD patterns show all characteristic of body-centered tetragonal anatase phase, according to JCPDS #00-021-1272 (data base);
  • The peaks are broad and low density, indicative of nano-sized-crystals;
  • The average diameters of the anatase crystallites (4.01~ 5.5 nm) nicely agree with the TEM crystallite size data;
  • The peaks overall get shorter and broader, revealing a decrease in crystallinity.
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