Electron diffractive imaging of oxygen atoms in nanocrystals at sub-ångström resolution.

High-resolution imaging of low-atomic-number chemical elements using electron microscopy is challenging and may require the use of high doses of electrons. Electron diffractive imaging, which creates real-space images using diffraction intensities and phase retrieval methods, could overcome such issues, although it is also subject to limitations. Here, we show that a combination of electron diffractive imaging and high-resolution transmission electron microscopy can image individual TiO(2) nanocrystals with a resolution of 70 pm while exposing the specimen to a low dose of electrons. Our approach, which does not require spherical and chromatic aberration correction, can reveal the location of light atoms (oxygen) in the crystal lattice. We find that the unit cell in nanoscale TiO(2) is subtly different to that in the corresponding bulk.

[1]  K. Urban,et al.  Studying Atomic Structures by Aberration-Corrected Transmission Electron Microscopy , 2008, Science.

[2]  I. Djerdj,et al.  An analysis of evolution of grain size-lattice parameters dependence in nanocrystalline TiO2 anatase , 2002 .

[3]  Pierre Stadelmann,et al.  EMS-A software package for electron diffraction analysis and HREM image simulation in materials science , 1987 .

[4]  Jian-Min Zuo,et al.  Coordination-dependent surface atomic contraction in nanocrystals revealed by coherent diffraction. , 2008, Nature materials.

[5]  S. Marchesini,et al.  X-ray image reconstruction from a diffraction pattern alone , 2003, physics/0306174.

[6]  P D Nellist,et al.  Direct Sub-Angstrom Imaging of a Crystal Lattice , 2004, Science.

[7]  L. Dubrovinsky,et al.  Nonlinear size dependence of anatase TiO2 lattice parameters , 2006 .

[8]  H. Fuess,,et al.  Rietveld analysis of electron powder diffraction data from nanocrystalline anatase, TiO2 , 2000, Ultramicroscopy.

[9]  Experimental design of exit wave reconstruction from a transmission electron microscope defocus series , 1993 .

[10]  Benedetta Carrozzini,et al.  Phasing at resolution higher than the experimental resolution. , 2005, Acta crystallographica. Section D, Biological crystallography.

[11]  R. Gerchberg.  A practical algorithm for the determination of phase from image and diffraction plane pictures , 1972 .

[12]  Garth J. Williams,et al.  Keyhole coherent diffractive imaging , 2008 .

[13]  M. V. Ganduglia-Pirovano,et al.  Oxygen vacancies in transition metal and rare earth oxides: Current state of understanding and remaining challenges , 2007 .

[14]  J. Miao,et al.  Extending the methodology of X-ray crystallography to allow imaging of micrometre-sized non-crystalline specimens , 1999, Nature.

[15]  Fang-hua Li,et al.  Image processing in high-resolution electron microscopy using the direct method.I.Phase extension , 1985 .

[16]  C. Giacovazzo,et al.  Ab initio phasing of proteins with heavy atoms at non-atomic resolution: pushing the size limit of solvable structures up to 7890 non-H atoms in the asymmetric unit , 2008 .

[17]  R. Bokel,et al.  Determination of the orientation in small areas of the exit wave. , 2001, Ultramicroscopy.

[18]  Henry N. Chapman,et al.  On the Extendibility of X‐ray Crystallography to Noncrystals , 1998 .

[19]  S Ramaseshan,et al.  Crystal Physics, Diffraction, Theoretical and General Crystallography , 1981 .

[20]  Xiaobo Chen,et al.  Titanium dioxide nanomaterials: synthesis, properties, modifications, and applications. , 2007, Chemical reviews.

[21]  W. Schaff,et al.  Direct Determination of Local Lattice Polarity in Crystals , 2006, Science.

[22]  S Marchesini,et al.  Invited article: a [corrected] unified evaluation of iterative projection algorithms for phase retrieval. , 2006, The Review of scientific instruments.

[23]  D. Muller.  Structure and bonding at the atomic scale by scanning transmission electron microscopy. , 2009, Nature materials.

[24]  P. Cozzoli,et al.  Low-temperature synthesis of soluble and processable organic-capped anatase TiO2 nanorods. , 2003, Journal of the American Chemical Society.

[25]  André C. Arsenault,et al.  Nanochemistry: A Chemical Approach to Nanomaterials , 2005 .

[26]  John T Yates,et al.  Surface science studies of the photoactivation of TiO2--new photochemical processes. , 2006, Chemical reviews.

[27]  Jian-Min Zuo,et al.  Sub-ångström-resolution diffractive imaging of single nanocrystals , 2009 .

[28]  P. Turner,et al.  Relativistic Hartree–Fock X‐ray and electron scattering factors , 1968 .

[29]  Transmission electron microscopy studies of nanostructured TiO2 films on various substrates , 2005 .

[30]  J. Banfield,et al.  The size dependence of the surface free energy of titania nanocrystals. , 2009, Physical chemistry chemical physics : PCCP.

[31]  Gianfranco Pacchioni,et al.  Nature of Ti Interstitials in Reduced Bulk Anatase and Rutile TiO2 , 2009 .

[32]  C. Giacovazzo,et al.  Quanto: a Rietveld program for quantitative phase analysis of polycrystalline mixtures , 2001 .

[33]  J. Zuo,et al.  Atomic Resolution Imaging of a Carbon Nanotube from Diffraction Intensities , 2003, Science.

[34]  S. Marchesini,et al.  Invited article: a [corrected] unified evaluation of iterative projection algorithms for phase retrieval. , 2006, The Review of scientific instruments.