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Crystallographic texture in ceramics and metals
No full textPreferred crystallographic orientation, or texture, occurs almost universally, both in natural and man-made systems. Many components and devices in electronic and magnetic systems are fabricated from materials that have crystallographic texture. With the rapidly increasing use of thin film technology, where sharp axisymmetric crystallographic texture normal to the film plane is frequently observed, the occurrence and impact of texture are rising. Thin film applications in which the texture of the material plays a key role in determining properties and performance are broad: complex oxides in random access memory devices, ZnO thin film resonators for cell phone applications, metallic alloys in magnetic recording media, and Al and Cu interconnects in integrated circuits are but a few examples. Texture is established during the synthesis or post-synthesis heat treatment of a material and thus has a strong dependence upon processing history. Accurate measurement of texture is not simple and a variety of tools and approaches are being actively employed in texture studies. X-ray, neutron and electron diffraction based techniques are practiced around the world at varying levels of complexity with regard to equipment and analysis methods. Despite the well-documented existence of these varied approaches, many reported texture measurements on electronic materials are based solely on the relative intensities of conventional theta-2theta x-ray diffraction peaks, which typically yield inaccurate results. NIST has developed quantitative texture measurement techniques that employ equipment commonly available in most industrial and academic settings. A number of examples of texture measurement in ceramic and metal systems will be presented, taken from the historical development and application of these techniques at NIST over the past 7 years
Contributions of NIST/NBS researchers to the crystallography of construction materials
No full textFor more than 100 years, the primary theme underlying the NBS/NIST staff contribution to the crystallography of building materials has been the development of an improved understanding of concrete materials performance. Over that time period, portland cement concrete has become one of the most important of our construction materials for roads, buildings, and other large municipal structures. At the beginning of the 20th century our understanding of portland cement composition, performance, use in concrete, and how the concrete performs in harsh environments was lacking. The efforts of NIST have served to advance construction materials science and technology through the combined efforts of experimental, field study, and theoretical computational materials science. One major achievement in the late 1920s, derived from studies on phase equilibria in cement clinker, allows calculation of potential cement clinker composition. Known as the Bogue calculation, this continues to be an essential tool in cement plant process control to this day. Additionally, contributions of NIST scientists to our knowledge of the chemistry and nature of cement hydration products have been crucial in our understanding of cement hydration and concrete durability. Today, computational materials science is a rapidly developing discipline, and NIST is developing tools incorporating predictive models aided by empirical studies. Examples include a computer-integrated knowledge system for prediction and optimization of performance and life-cycle cost of high performance concrete and the Virtual Cement and Concrete Testing Laboratory. Understanding the relationships between material and performance properties has not been confined only to portland cements. One of the longest running experiments at NIST, the stone test wall, has stood for over 50 years as one of the worlds largest single collections of building stone, and is invaluable for studying weathering effects associated with stone mineralogy and texture. Standards development has also been promoted through participation on ASTM subcommittees on stone, cement, and concrete. The Cement and Concrete Reference Laboratory, established in 1929, continues to provide testing and training for outside laboratories and maintains a historical record of test data on construction materials
Vibrational branching ratios and asymmetry parameters in the photoionization of CO2 in the region between 650 angstrom and 840 angstrom
No full textThe vibrational branching ratios and asymmetry parameters for CO2 have been determined in the wavelength region of 650 Angstrom to near the ionization onset at about 840 Angstrom. The study was performed using synchrotron radiation from the Daresbury storage ring that was dispersed with a 5 m grating monochomator that afforded resolution of 0.1 Angstrom to 0.2 Angstrom. This resolution allowed the study of the branching ratios and asymmetry parameters with enough detail to see the changes in the parameters within the pronounced autoionization structure in CO2 in this wavelength region. While the electron spectrometer resolution was not sufficient to resolve the spin orbit and Renner-Teller splitting in the photoelectron spectra, we are able to fit the data with a model that identifies the major structure in terms of the symmetric stretch and elements of the asymmetric stretch and bending modes. A calculation of the expected relative vibrational excitations based upon the Franck-Condon principle clearly showed non-Franck-Condon behavior in some of the vibrational-electronic transitions
Lattice symmetry and identification - The fundamental role of reduced cells in materials characterization
No full textIn theory, physical crystals can be represented by idealized mathematical lattices. Under appropriate conditions, these representations can be used for a variety of purposes such as identifying, classifying, and understanding the physical properties of materials. Critical to these applications is the ability to construct a unique representation of the lattice. The vital link that enabled this theory to be realized in practice was provided by the 1970 paper on the determination of reduced cells. This seminal paper led to a mathematical approach to lattice analysis initially based on systematic reduction procedures and the use of standard cells. Subsequently, the process evolved to a matrix approach based on group theory and linear algebra that offered a more abstract and powerful way to look at lattices and their properties. Application of the reduced cell to both database work and laboratory research at NIST was immediately successful. Currently, this cell and/or procedures based on reduction are widely and routinely used by the general scientific community: (i) for calculating standard cells for the reporting of crystalline materials, (ii) for classifying materials, (iii) in crystallographic database work (iv) in routine x-ray and neutron diffractometry, and (v) in general crystallographic research. Especially important is its use in symmetry determination and in identification. The focus herein is on the role of the reduced cell in lattice symmetry determination
Phase equilibria and crystallography of ceramic oxides
No full textResearch in phase equilibria and crystallography has been a tradition in the Ceramics Division at National Bureau of Standards/National Institute of Standatrds and Technology (NBS/NIST) since the early thirties. In the early years, effort was concentrated in areas of Portland cement, ceramic glazes and glasses, instrument bearings, and battery materials. In the past 40 years, a large portion of the work was related to electronic materials, including ferroelectrics, piezoelectrics, ionic conductors, dielectrics, microwave dielectrics, and high-temperature superconductors. As a result of the phase equilibria studies, many new compounds have been discovered. Some of these discoveries have had a significant impact on US industry. Structure determinations of these new phases have often been carried out as a joint effort among NBS/NIST colleagues and also with outside collaborators using both single crystal and neutron and x-ray powder diffraction techniques. All phase equilibria diagrams were included in Phase Diagrams for Ceramists, which are collaborative publications between The American Ceramic Society ( ACerS) and NBS/NIST. All x-ray powder diffraction patterns have been included in the Powder Diffraction File ( PDF). This article gives a brief account of the history of the development of the phase equilibria and crystallographic research on ceramic oxides in the Ceramics Division. Represented systems, particularly electronic materials, are highlighted
Richard D. Marshall
No full textRICHARD D. MARSHALL
Inducted: 2001
Citation:
For structural and wind engineering research with significant contributions to the estimation of hurricane wind speeds, the effects of wind loads on buildings and other structures, and the improvement of national building standards and codes
Tenure: 1968-1996
Birth: 1934, Mandan, North Dakota
Death: 2000, Rockville, Maryland
Education:
North Dakota State University, BS (civil engineering), 1956
University of Colorado, MS (civil engineering), 1959
Colorado State University, PhD, 1968
Positions held:
Research Structural Engineer, Structures Division, Building and Fire Research Laboratory
Leader, Structural Evaluation Group, Structures Division, Building and Fire Research Laboratory
Honors:
U.S. Department of Commerce: Silver Medal, 1975; Gold Medal, 1982
National Hurricane Conference Engineering Award, 1991 and 1997
ASCE/SEI Walter P. Moore Jr. Award, 1998
Colorado State University Lifetime Achievement Award, 1999
Memberships:
American Society of Civil Engineers
Wind Research Council
Publications:
Over 100 technical publications in structural and wind engineering with significant contributions in the estimation of hurricane wind speeds, the effects of wind loads on buildings and other structures, and the impro
Four dinner guests at the NIST 2001 Centennial Gala
No full text(L to R) Joe Reader, Mrs. Reader, Mrs. Deslattes, and Richard "Dick" Deslattes attending the NIST 2001 Centennial Gala dinner on March 6, 2001.
NIST hosted a number of celebratory events to mark the 100th anniversary of its founding. The NIST Centennial Gala was held on March 6, 2001. The evening's program included remarks by US Secretary of Commerce Donald Evans
NIST 2001 Centennial Gala dinner guests, including Reeves Tilley (2nd from left)
No full textJerome Kruger, aka NIST’s 'Mr. Corrosion' (left) with W. Reeves Tilley (second from left) and two guests at the
NIST Centennial Gala held on March 6, 2001.
NIST hosted a number of celebratory events to mark the 100th anniversary of its founding. The NIST Centennial Gala was held on March 6, 2001. The evening's program included remarks by US Secretary of Commerce Donald Evans
John Mayo-Wells and Karen Brown with the time capsule during the NIST 2001 Centennial
No full textJohn Mayo-Wells and Karen Brown in the NIST Gaithersburg red auditorium with the centennial time capsule during the NIST 2001 Centennial.
NIST celebrated its centennial in March 2001. Attendees included Acting NIST Director Karen Brown, NIST staff, alumni, and guests. This image is part of the NIST 2001 Centennial collection. The NIST 2001 Centennial collection includes images of various celebrations of the 100th anniversary of the National Institute of Standards and Technology (NIST), previously known as the National Bureau of Standards
Lewis Branscomb delivering address at the grand opening of the Lobby and Information Center during the NIST 2001 Centennial
No full textLewis Branscomb, NIST Director 1969-1972. NIST celebrated the grand opening of its Lobby and Information Center during its March 2001 Centennial Celebration. Attendees at the opening included Acting NIST Director Karen Brown, NIST staff, alumni, and guests. This image is part of the NIST 2001 Centennial collection. The NIST 2001 Centennial collection includes images of various celebrations of the 100th anniversary of the National Institute of Standards and Technology (NIST), previously known as the National Bureau of Standards