Nanocrystalline TiO2 preparation by microwave route and nature of anatase–rutile phase transition in nano TiO2

Abstract

Nanopowders of TiO 2 has been prepared using a microwave irradiation-assisted route, starting from a metalorganic precursor, bis(ethyl-3-oxo-butanoato)oxotitanium (IV), [TiO(etob) 2 ] 2. Polyvinylpyrrolidone (PVP) was used as a capping agent. The as-prepared amorphous powders crystallize into anatase phase, when calcined. At higher calcination temperature, the rutile phase is observed to form in increasing quantities as the calcination temperature is raised. The structural and physicochemical properties were measured using XRD, FT-IR, SEM, TEM and thermal analyses. The mechanisms of formation of nano-TiO 2 from the metal-organic precursor and the irreversible phase transformation of nano TiO 2 from anatase to rutile structure at higher temperatures have been discussed. It is suggested that a unique step of initiation of transformation takes place in Ti 1/2 O layers in anatase which propagates. This mechanism rationalizes several key observations associated with the anatase-rutile transformation.

Preparation of N doped TiO2 via microwave-assisted method and its photocatalytic activity for degradation of Malathion

“…Nowadays, preparation of N-doped TiO 2 with anatase phase has been of great interest for photocatalytic applications. Although, there are several methods are available for the preparation of metal oxide nanomaterials but the microwave assisted technique has potential advantages over the conventional methods such as the growth rate of product is very high for small particle size and always the product exhibits a narrow size distribution as a consequence of fast homogenous nucleation, molecular homogeneity and selective heating rate [17].…”

Understanding the phenomenon of x-ray diffraction by crystals and related concepts

“…The grain size increased from 100 • C to 200 • C but there was a decrease at 300 • C. No anatase phase was found in the range of tested temperatures. Neelgund et al (2011) applied a microwave method of preparation of nanoparticles of TiO 2 and calcinated them at 150, 400, 500, 600, 700 and 800 • C. At 150 • C they found an amorphous structure. At 400 • C the XRD pattern corresponded to the anatase phase.…”

Hydrothermal Transformation of Titanate Scrolled Nanosheets to Anatase over a Wide pH Range and Contribution of Triethanolamine and Oleic Acid to Control the Morphology

“…The synthesis of these titania-based nanotubes (TNTs), also referred to as scrolled nanosheets (SNSs), is based on the hydrothermal treatment of TiO 2 powder, at high temperatures in a highly concentrated NaOH solution without sacrificial templates and was first reported by Kasuga et al , in 1998. This simple and cost-effective hydrothermal method provides a large-scale quantity of pure titania-based nanotubes with small diameter (9–10 nm) and lengths as high as several hundred nanometers and has been the subject of many efforts. ,, The different studies on the reactivity of these SNSs in various media ,,− show they can be effectively used as a cost-effective starting material as compared to titanium alkoxides for the controlled synthesis of targeted morphologies of TiO 2 . We propose in this paper to use these SNSs in hydrothermal conditions under mild conditions (140 °C, 3 d) and scan the influence of parameters such the pH and the nature of the capping agents suggested by Sugimoto to direct NPs growth starting from molecular precursors .…”