We report on structural and optical changes induced by impurity incorporation in ZnO nanorods grown via electrodeposition. We find the lattice parameters of the hexagonal ZnO rods to be larger than in defect-free single-crystalline ZnO. SIMS measurements indicate impurity incorporation and doping in the bulk of the nanorods. The impurity content correlates with changes in the electroluminescence spectra. The maximum of the defect luminescence band around 600 nm shifts towards longer wavelengths with metal incorporation. Aluminum incorporation leads to a narrow luminescence band close by the bandgap of ZnO around 390 nm. Published by Elsevier B.V.

A brief introduction to lattice fringe fingerprinting in two dimensions (2D) with database support is given. The method is employed for the identification of the crystal phase of a small ensemble of nanocrystals. The enhanced viability of this method in aberration-corrected transmission electron microscopes (TEMs) and scanning TEMs (STEMs) is also illustrated.

Terry Maguire, International Centre for Diffraction Data, Newtown Square, PA 19073 The International Centre for Diffraction Data held its Annual Spring Meetings at the Newtown Square Headquarters during the week of 20–24 March 2006. ICDD members and guests from around the world benefited from interactions with fellow scientists working in various fields of materials characterization. The spring meetings also provided forums to discuss the business and technical aspects of the ICDD and the Powder Diffraction FileTM. A Plenary Session was held on Tuesday, March 21, and featured guest speakers from Venezuela and Japan, Professors José Miguel Delgado and Nobuo Ishizawa. Dr. John Faber, ICDD’s Principal Scientist discussed the development of PDF-4 , ICDD’s newest product, and future product enhancements. Finally, Scott Sitzman of HKL Technology, Inc. highlighted some recent developments in electron backscatter diffraction analysis.

Gallium nitride powders were calcined with copper oxide in either air or N 2 and analyzed by means of powder X-ray diffraction (XRD), high-resolution parallel illumination (HRTEM) and scanning probe transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDXS), and electron energy loss spectroscopy (EELS) in order to address the structural and electronic effects of Cu-incorporation into GaN. Gallium oxide and multiple copper oxide phases corresponding to the calcination environment were detected. Significant changes in the lattice parameters and electronic structure of the N 2 -processed GaN indicate incorporation of both copper and oxygen into the GaN lattice as well as changes in the chemical bonding due to the calcinations process. SQUID magnetometer measurements at 300 K demonstrated ferromagnetism in selected samples.

Because a great deal of nanoscience and nanotechnology relies on crystalline nanometer sized or nanometer structured materials, crystallographers have to provide their specific contributions to the National Nanotechnology Initiative. Here we review two open access internet-based crystallographic databases, the Crystallography Open Database (COD) and the Nano-Crystallography Database (NCD), that store information in the Crystallographic Information File (CIF) format. Having more than ten thousand crystallographic data sets available on the internet in a standardized format allows for many kinds of internet-based crystallographic calculations and visualizations. Examples for this that are dealt with in this paper are interactive crystal structure visualizations in three dimensions (3D) and calculations of theoretical lattice-fringe fingerprint plots for the identification of unknown nanocrystals from their atomic-resolution transmission electron microscopy images.

Crystallographic databases for inorganic materials that are freely accessible over the internet are reviewed. The Nano-Crystallography Database project is described. Instructions are given on how to visualize in three dimensions the atomic arrangements of several thousand entries of the Crystallography Open Database.

Powder X-ray diffraction analyses of Mn-and Cu-doped ZnO powders calcined at 500˚C, show shifts in the wurtzite type semiconductor's lattice constants and unit cell volume which correspond to the nominal concentrations of transition metal dopants. Marked reductions in the a-lattice constant and unit cell volume for a small concentration of Cu dopants, which is not maintained upon increased Cu concentration, suggest a change in the copper ion hybridization state due to the dopant concentration. In all the samples, only ZnO and CuO phases were detected, aiding the ascertainment of any ferromagnetic response from the samples as arising from the formation of a true dilute magnetic semiconductor.

Extract HTML view is not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button. Extended abstract of a paper presented at Microscopy and Microanalysis 2005 in Honolulu, Hawaii, USA, July 31--August 4, 2005

New needs to determine the crystallography of nanocrystals arise with the advent of science and engineering on the nanometer scale. Direct space high-resolution phase-contrast transmission electron microscopy (HRTEM) and atomic resolution Z-contrast scanning TEM (Z-STEM), when combined with tools for image-based nanocrystallography possess the capacity to meet these needs. This paper introduces such a tool, i.e. fringe fingerprinting in two dimensions (2D), for the identification of unknown nanocrystal phases and compares this method briefly to qualitative standard powder X-ray diffractometry (i.e. spatial frequency fingerprinting). Free-access crystallographic databases are also discussed because the whole fingerprinting concept is only viable if there are comprehensive databases to support the identification of an unknown nanocrystal phase. This discussion provides the rationale for our ongoing development of a dedicated free-access Nano-Crystallography Database (NCD) that contains comprehensive information on both nanocrystal structures and morphologies. The current status of the NCD project and plans for its future developments are briefly outlined. Although feasible in contemporary HRTEMs and Z-STEMs, fringe fingerprinting in 2D (and image-based nanocrystallography in general) will become much more viable with the increased availability of aberration-corrected transmission electron microscopes. When the image acquisition and interpretation are, in addition, automated in such microscopes, fringe fingerprinting in 2D will be able to compete with powder X-ray diffraction for the identification of unknown nanocrystal phases on a routine basis. Since it possesses a range of advantages over powder X-ray diffractometry, e.g., fringe fingerprint plots contain much more information for the identification of an unknown crystal phase, fringe fingerprinting in 2D may then capture a significant part of the nanocrystal metrology market.

Journal Article Image-based 3D Nanocrystallography by Means of Tilt Protocol/Lattice-Fringe Fingerprinting with Contemporary Side-entry Specimen Goniometers Get access P Moeck, P Moeck Portland State University, Portland, Oregon Search for other works by this author on: Oxford Academic Google Scholar B Seipel, B Seipel Portland State University, Portland, Oregon Search for other works by this author on: Oxford Academic Google Scholar W Qin, W Qin Freescale Semiconductor, Chandler, Arizona Search for other works by this author on: Oxford Academic Google Scholar E Mandell, E Mandell University of Missouri St. Louis, St. Louis, Missouri Search for other works by this author on: Oxford Academic Google Scholar P Fraundorf P Fraundorf University of Missouri St. Louis, St. Louis, Missouri Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 11, Issue S02, 1 August 2005, Pages 632–633, https://doi.org/10.1017/S1431927605500564 Published: 01 August 2005

Extended abstract of a paper presented at the Pre-Meeting Congress: Materials Research in an Aberration-Free Environment, at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, July 31 and August 1, 2004.

We analysed x-ray powder diffraction data of spray pyrolytic precursor powders for the oxide-powder-in-tube (OPIT) technology by means of the Rietveld method. For calcinations in air we find a typical phase composition of 2212, 14-24, 11, CP and 3321 at 800 °C (13 h). At 820 °C 2212 is in equilibrium with 14-24 and CP after 48 h calcination. In 8% O2 at 800 °C 2212 exists together with 14-24, 21, CP and CuO, in 99.999% N2 at 760 °C the stable phase assemblage consists of 2212, 21 and CuO. The highest amount of 2212 can be found in the powder calcined at 8% O2 (72.4 wt%) compared with 68.9 wt% for the powder calcined in 21% O2 and 69.3 wt% for the powder calcined in flowing N2. A first trace of 2223 can be observed in powders calcined in air at temperatures of 838 °C and 842 °C. The crystallographic features of the 2212 phase correlate with the calcination atmosphere: under reducing atmospheres the satellite reflections of the x-ray powder diffractogram disappear and the orthorhombic lattice distortion z increases due to Pb2+-incorporation into 2212. With increasing O-content the c lattice parameter becomes significantly shorter in samples calcined in oxidizing atmospheres. It is possible to infer a cationic ratio of Sr:(Sr + Ca) ≈ 0.12 for the 11 phase and Ca:(Ca + Sr + Bi) ≈ 0.57 for 14-24 in precursors from lattice parameter data.

Crystallographic databases for inorganic materials that are freely accessible over the internet are reviewed. The Nano-Crystallography Database project is described. Instructions are given on how to visualize in three dimensions the atomic arrangements of several thousand entries of the Crystallography Open Database.