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Low temperature nanostructured lithium titanates: Controlling the phase composition, crystal structure and surface area

Mohammadi, M. R ; Sharif University of Technology | 2010

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  1. Type of Document: Article
  2. DOI: 10.1007/s10971-010-2209-6
  3. Publisher: 2010
  4. Abstract:
  5. Low temperature lithium titanate compounds (i.e., Li4Ti 5O12 and Li2TiO3) with nanocrystalline and mesoporous structure were prepared by a straightforward aqueous particulate sol-gel route. The effect of Li:Ti molar ratio was studied on crystallisation behaviour of lithium titanates. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) revealed that the powders were crystallised at the low temperature of 500 °C and the short annealing time of 1 h. Moreover, it was found that Li:Ti molar ratio and annealing temperature influence the preferable orientation growth of the lithium titanate compounds. Transmission electron microscope (TEM) images showed that the average crystallite size of the powders annealed at 400 °C was in the range 2-4 nm and a gradual increase occurred up to 10 nm by heat treatment at 800 °C. Field emission scanning electron microscope (FE-SEM) analysis revealed that the deposited thin films had mesoporous and nanocrystalline structure with the average grain size of 21-28 nm at 600 °C and 49-62 nm at 800 °C depending upon the Li:Ti molar ratio. Moreover, atomic force microscope (AFM) images confirmed that the lithium titanate films had columnar like morphology at 600 °C, whereas they showed hill-valley like morphology at 800 °C. Based on Brunauer-Emmett-Taylor (BET) analysis, the synthesized powders showed mesoporous structure containing pores with needle and plate shapes. The surface area of the powders was enhanced by increasing Li:Ti molar ratio and reached as high as 77 m2/g for the ratio of Li:Ti = 75:25 at 500 °C. This is one of the smallest crystallite size and the highest surface areas reported in the literature, and the materials could be used in many applications such as rechargeable lithium batteries and tritium breeding materials
  6. Keywords:
  7. Low temperature ; Sol-gel ; Annealing temperatures ; Annealing time ; Atomic force microscopes ; Average grain size ; Crystallisation ; Field emission scanning electron microscopes ; Lithium titanate ; Low temperatures ; Mesoporous ; Mesoporous structures ; Molar ratio ; Nano-crystalline structures ; Nano-structured ; Nanocrystalline ; Nanocrystallines ; Orientation growth ; Plate shape ; Rechargeable lithium battery ; Sol-gel routes ; Surface area ; Synthesized powder ; TiO ; Transmission electron microscope ; Tritium breeding materials ; Annealing ; Crystal structure ; Crystallite size ; Electron microscopes ; Field emission ; Fourier transform infrared spectroscopy ; Fourier transforms ; Gels ; Lithium compounds ; Morphology ; Nanocrystalline alloys ; Nanocrystalline powders ; Scanning electron microscopy ; Sol-gel process ; Sol-gels ; Sols ; Surface structure ; Transmission electron microscopy ; Tritium ; Wavelet transforms ; X ray diffraction ; X ray powder diffraction ; Lithium
  8. Source: Journal of Sol-Gel Science and Technology ; Volume 55, Issue 1 , 2010 , Pages 19-35 ; 09280707 (ISSN)
  9. URL: http://link.springer.com/article/10.1007%2Fs10971-010-2209-6