In situ high-temperature electron microscopy of 3DOM cobalt, iron oxide, and nickel
- 359 Downloads
High-temperature electron microscopy was used to follow how the structure of two specimens of three-dimensionally ordered macroporous (3DOM) materials, also known as inverse opals, and one specimen of a precursor to a 3DOM material changed with temperature. The change in grain size with temperature of 3DOM cobalt and 3DOM iron oxide (as magnetite) was monitored in situ in the TEM by heating in stages to 900 and 1,000 °C, respectively. The two materials studied by TEM showed contrasting grain growth behavior. For 3DOM cobalt, carbon surrounding the nanometer-size grains led to slower grain growth in thinner sample areas than in areas in closer contact with other grains; a bimodal grain-size distribution was observed after heating above 700 °C for 90 min. The grains of the 3DOM iron oxide had no carbon coating and coarsened more evenly to give a unimodal size distribution. Line scans from selected-area diffraction (SAD) patterns were used for phase analysis and showed that traces of cobalt oxide present in the 3DOM cobalt sample at room temperature disappeared when the sample was heated above 500 °C. The transformation of a 3DOM precursor material, nickel(II) oxalate–polystyrene (PS) latex composites, was followed in situ by variable-temperature environmental scanning electron microscopy (ESEM) from room temperature to ca. 700 °C in 0.5–0.7 kPa O2. The ESEM examination of the 3DOM precursors permitted real-time observation of the polymer template decomposition and the shrinkage that occurs upon calcination of these precursor materials.
KeywordsEnvironmental Scanning Electron Microscopy Colloidal Crystal Powder Diffraction File Cobalt Metal Lithium Iron Phosphate
The authors thank Dr. Hongwei Yan for providing the samples of 3DOM materials, Dr. Stuart McKernan for assistance with the ESEM and TEM, and the David and Lucile Packard Foundation and the 3M Heltzer Endowed Chair of the University of Minnesota for research funding.
- 4.Lytle JC, Stein A (2006) In: Cao G, Brinker CJ (eds) Annual reviews of nano research. World Scientific Publishing, Hackensack, NJ, pp 1Google Scholar
- 8.Joannopoulos JD, Meade RD, Winn JN (1995) Photonic crystals: molding the flow of light. Princeton University Press, PrincetonGoogle Scholar
- 11.van Bekkum H, Flanigen EM, Jansen JC (1991) Introduction to zeolite science and practice. Elsevier, AmsterdamGoogle Scholar
- 26.Schroden RC, Stein A (2004) In: Caruso F (ed) Colloids and colloid assemblies: synthesis, modification, organization and utilization of colloid particles. Wiley VCH, Weinheim, Germany, pp 465Google Scholar
- 28.Anderson MW, Ohsuna T, Sakamoto Y, Liu Z, Carlsson A, Terasaki O (2004) Chem Commun 907Google Scholar
- 29.Kamino T, Yaguchi T, Konno M, Hashimoto T (2005) J Electron Microsc 54:461Google Scholar
- 44.Blanford CF (2000) Ph.D. Dissertation, University of Minnesota, Twin CitiesGoogle Scholar
- 61.Lide DR (ed) (1996) CRC handbook of chemistry and physics. CRC Press, Ann ArborGoogle Scholar
- 68.Carter CB, Norton MG (2007) Ceramic materials: science and engineering. Springer-Verlag, New YorkGoogle Scholar