Howard F. McMurdie

Methods of Producing Standard X-Ray Diffraction Powder Patterns

Patterns useful for identification are obtained by automated diffractometer methods. The lattice constants from the experimental work are refined by least-squares methods; reflections are assigned hkl indices consistent with space group extinctions. Relative intensities, calculated densities, literature references, and other relevant data are included.

JCPDS-ICDD Research Associateship (cooperative program with NBS/NIST)

The Research Associateship program of the Joint Committee on Powder Diffraction-International Centre for Diffraction Data (JCPDS-ICDD, now known as the ICDD) at NBS/NIST was a long standing (over 35 years) successful industry-government cooperation. The main mission of the Associateship was to publish high quality x-ray reference patterns to be included in the Powder Diffraction File (PDF). The PDF is a continuing compilation of patterns gathered from many sources, compiled and published by the ICDD. As a result of this collaboration, more than 1500 high quality powder diffraction patterns, which have had a significant impact on the scientific community, were reported. In addition, various research collaborations with NBS/NIST also led to the development of several standard reference materials (SRMs) for instrument calibration and quantitative analyses, and computer software for data collection, calibration, reduction, for the editorial process of powder pattern publication, analysis of powder data, and for quantitative analyses. This article summarizes information concerning the JCPDS-ICDD organization, the Powder Diffraction File (PDF), history and accomplishments of the JCPDS-ICDD Research Associateship.

Standard X-Ray Diffraction Powder Patterns of Fifteen Ceramic Phases

Fifteen reference patterns of oxide ceramics are reported. Included in the fifteen reference patterns are data for nine high critical temperature superconducting oxide and related phases Ba 2 Cu 3 ErO 7 , Ba 3.2 Cu 1.7 Er 0.8 O 6.1 ·xCO 2 , Ba 2 Cu 3 HoO 7 , Ba 2 Cu 3 (Pr 0.5 Y 0.5 )O 7 , Ba 3 Dy 4 O 9 , Ba 3 Yb 4 O 9 , (Ba 0.6 Sr 0.4 ) 2 Cu 3 YO 7 , (Ba 0.8 Sr 0.2 ) 2 Cu 3 YO 7 , and CuNd 2 O 4 . The general methods of producing diese X-ray powder diffraction reference patterns were described previously in this journal (Vol. 1, No. 1, pg. 40 (1986)). The symbols used in diis article are defined in the PDF cards.

Reference X-Ray Diffraction Powder Patterns of Fifteen Ceramic Phases

Fifteen reference patterns of boride, silicide, selenide, telluride and oxide ceramics are reported. Included in the 15 reference patterns are data for three oxide phases which are related to high critical temperature (T c ) superconducting materials: BaCuO 2 , BaCuSm 2 O 5 and BaCuYb 2 O 5 . Four other patterns are included which represent phases previously not contained in the PDF. The remaining six are major corrections of data already included in the file. Reference data for phases Ba 2 CuY 3 O 6.8 and Ba 2 Y 3 CuO 6 appeared in the special July superconductor issue of the Advanced Ceramic Materials , 1987. The general methods of producing these X-ray powder diffraction reference patterns are described in this journal, Vol. 1(1), 40 (1986). Samples were mixed with one or two internal standards: silicon (SRM640a), silver, tungsten, or fluorophlogopite (SRM675). Expected 2θ values for these internal standards are specified in the methods described ( ibid. ). Data were measured with a computer controlled diffractometer. The POWDER-PATTERN system of computer programs was used to locate peak positions, to calibrate the patterns, and to perform variable indexing and least-squares cell refinement. A check on the overall internal consistency of the data was also provided by a computer program.

Phase Equilibria and Crystallography of Ceramic Oxides

Research 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.