Foreword.

This Special Issue, which focuses on crystallography, is part of The Centennial Celebration of the National Institute of Standards and Technology (NIST), formerly known as the National Bureau of Standards (NBS). NBS/NIST has a long history (more than 50 years) of crystallographic research with contributions from many scientists from various divisions and diverse disciplines. The research was carried out as a fundamental part of the overall mission of NBS/NIST and its research programs. The mission of NBS/NIST enables its scientists to undertake large, long-term, research projects to develop fundamental understanding, data, and measurement methods that result in significant bodies of work and create a stimulating research environment. Crystallography represents one such area and this Special Issue was assembled to review work in this area by giving a brief overview of the role of crystallography at NBS/NIST--past, present, and future.

The articles cover a broad spectrum of topics including high-pressure crystallography, magnetic structure determinations, quasi-crystals, novel biomaterials, biological minerals, structure determination via neutron and x-ray diffraction, reduced cells, standard reference materials, phase equilibria and ceramic oxides, crystallographic texture, zeolitic materials, near perfect crystals, electron diffraction, crystallographic databases, protein crystallography, crystallography in construction, and synchrotron radiation. The articles are preceded by a memorial tribute to Richard Deslattes, a highly respected NBS/NIST scientist who is well known throughout the United States and the international scientific communities. His major scientific contributions were in the fields of x-ray physics, precision measurements and fundamental constants.

There is scientific diversity in the articles along with a number of fascinating highlights. For example, the article on quasi-crystals strikes at the fundamental definition of a crystal lattice. The article on bone cement shows that specialized crystalline materials can be designed to play a vital role in orthopedic surgical procedures. Several of the papers demonstrate that some of the outstanding achievements at NBS/NIST were arrived at by serendipity--not a direct part of a "defined" project, but arising from a creative and stimulating scientific environment. This type of research has long been an integral part of the synergistic NBS/NIST culture. For example, the diamond anvil pressure cell was invented "by scientists of different interests, different research activities and different backgrounds, who interacted on a professional level and recognized an opportunity to make a significant contribution to scientific research."

From these articles, it is obvious that crystallographic research at NBS/NIST will continue to play an important role in the future. The development of new and novel materials, material characterization techniques, standards, and standard reference materials will continue to be vital to the scientific community and the nation's economy. Several broad themes are apparent: (1) that collaborative efforts with outside organizations and individuals will continue to be an important part of the NBS/NIST research culture; (2) that instrumentation will continue to be emphasized; and (3) that work on databases will expand to meet the needs of the scientific community.

An especially important NBS/NIST activity is the development of state-of-the-art instrumentation and making it available to the scientific community. In particular, ar ticles on the NIST Center for Neutron Research capabilities describe the elegant instrumentation available for the rapid collection of neutron powder diffraction data and for property measurement. This equipment has provided the data required to solve and understand many unique structures of critical scientific importance, e.g., superconductors. These structure solutions have helped revolutionize concepts in inorganic chemistry. Similarly, another article gives a detailed discussion on the NBS/NIST synchrotron facilities for materials science.

NBS/NIST has long supported collaborative research efforts with external groups. Accordingly, several such efforts are illustrated in the articles. For example, the Polymers Division and the American Dental Association have collaborated in research on dental materials for many years. An article on the development of a novel bone cement illustrates a medically important biomaterial that is a product of this collaboration. Another long-term and fruitful collaboration has been that between NBS/NIST and the International Centre for Diffraction Data (ICDD). This effort has focused on collecting and evaluating data for the Powder Diffraction File, a database that is used in laboratories worldwide for materials characterization. Finally, a "Research Collaboratory for Structural Bioinformatics (RCSB)," involving three groups, has recently been created.

Another theme embodied in this Special Issue is the increasing realization of the critical importance of crystallographic data centers to the needs of the scientific community. Concepts and software developed at NBS/NIST for the standardization of lattice parameters, for symmetry determination and for identification are widely used by the scientific community. In the future, computer-driven scientific instruments will funnel data into the public domain at an unprecedented rate. In response, there will be an increasing emphasis on computational techniques to work with and exploit this data. This trend is demonstrated by the creation of crystallographic databases in support of materials development. To handle the deluge of protein data, NIST, in partnership with Rutgers University and the UCSD, formed the RCSB, which acquired the Protein Data Bank in 1997. An important future role of NIST in crystallographic databases will be to set data standards, provide accessibility, interlink data, evaluate information, an d create research and data mining software tools.

Leslie E. Smith

Director, Materials Science and Engineering Laboratory Chair, NIST Centennial Committee