Synthesis of mesoporous zirconium titanates using alkycarboxylate surfactants and their transformation to dense ceramics Vittorio Luca * , Willem K. Bertram, Jonathan Widjaja, David R.G. Mitchell, Christopher S. Griffith, Elizabeth Drabarek Australian Nuclear Science and Technology Organization, Institute of Materials and Engineering Sciences, PMB 1, Menai, NSW 2234, Australia Received 22 June 2006; received in revised form 4 January 2007; accepted 9 January 2007 Available online 25 January 2007 Abstract Mesoporous zirconium titanates with Ti/Zr ratios of two have been prepared through the controlled hydrolysis of mixtures of zirco- nium and titanium alkoxides and long chain carboxylates (lauric, palmitic or stearic acids) in the absence of solvent. X-ray diffraction, transmission electron microscopy, and gas adsorption measurements indicate that the zirconium titanate mesophases consist of a disor- dered arrangement of uniform pores. The average pore diameter obtained depends on the carboxylate chain length. These zirconium titanate mesophases are stable to temperatures in excess of 600 °C and possess a uniform distribution of Zr and Ti within the pore walls without the formation of extraneous phases as determined by XRD and energy dispersive X-ray analysis. The formation of the meso- phase was also investigated by small angle X-ray scattering which shows the growth of fractal structures as a function of time. When impregnated with calcium ions the reactive mesoporous precursor can be converted to the dense ceramic, zirconolite, at temperatures as low as 900 °C. The zirconolites formed using the present methods exhibit some compositional variability. Crown Copyright Ó 2007 Published by Elsevier Inc. All rights reserved. Keywords: Mesoporous; Zirconium; Titanium; Carboxylate; Lauric; Palmitic; Stearic 1. Introduction The preparation of mesoporous transition metal oxide materials using surfactant self-assembly has attracted con- siderable interest this decade [1,2]. For the specific case of titanium oxide-based mesophases, much of the interest stems from the unique chemical and semiconducting prop- erties of this oxide which leads to important potential applications in the fields of catalysis, electrochemistry and optoelectronics. As a consequence there have now been many reports of titanium oxide [3–6] and oxo-phos- phate mesophase materials [7] with considerable recent emphasis being placed on thin films [8–14]. There are virtu- ally no reports of the preparation of high quality bulk mes- oporous titanium oxide materials having high thermal stability (>400 °C) even though such materials are no less useful especially for applications in adsorption and cataly- sis. Perhaps of lesser technological significance, but never- theless also much studied, are mesoporous zirconium oxides and zirconium oxo-sulfate and phosphates [15–22]. In this case mostly bulk materials have been studied. Areas that are now receiving increased attention are the preparation of bulk mesoporous mixed metal oxides and materials with unique porosity including the region of porosity below about 3 nm. Mixed mesoporous metal oxi- des can potentially offer a modulation of surface acidity, thermal stability, and redox activity leading to enhanced activities and different applications compared with the pure oxides [23]. The review by Reddy and Khan [24] provides a striking example of the superiority of mixed ZrO 2 –TiO 2 xerogels compared with either individual component in cat- alytic applications. Another example is provided by Schattka et al. [25] who have prepared macroporous mixed Ti–Zr oxides with Ti/Zr ratios ranging from 0 to 1 and sur- 1387-1811/$ - see front matter Crown Copyright Ó 2007 Published by Elsevier Inc. All rights reserved. doi:10.1016/j.micromeso.2007.01.024 * Corresponding author. Tel.: +61 2 9717 3087; fax: +61 2 9543 7179. E-mail address: vlu@ansto.gov.au (V. Luca). www.elsevier.com/locate/micromeso Microporous and Mesoporous Materials 103 (2007) 123–133