Fracture accidents of engineering structures and machines in operation sometimes result from defects. One of the purposes of fracture analysis are to determine the causes of failure, and to use the information to prevent similar failure accidents. It is important to obtain quantitative analysis from the fracture surface. X-ray diffraction technique as well as Electron Fraotography has been widely used for fracture analysis of engineering structures and machines.

We report the implementation of two new methods of accurate comparison of lattice parameters against a silicon standard using a high resolution X-ray diffractometer. The double axis method uses a specimen rotation stage which set the limit of reproducibility (at 3 sigma) to 3 parts in 105. An application of the technique is illustrated in measurements of the zinc concentration in Cd1-xZnx Te to an accuracy of 0.1%. The triple axis technique uses beam conditioner and analyser crystals to define the incident and diffracted wave vectors. In measurement of the lattice parameters of InAs, we found a precision of 1 part in 105 and traceable accuracy of a several parts in 105.

In this paper, the application of recently developed x-ray diffraction techniques to the characterization of thin epitaxial films will be discussed. The double-crystal diffractometer, with high resolution in the non-dispersive arrangement, enables the materials scientist to study epitaxial systems having a very small mismatch with high precision. A key part of the characterization of an epitaxial film is the determination of the strain tensor by measuring lattice spacing! in various directions The determination of strain and composition profiles in ion-implanted films, epitaxial layers and superlattices by rocking-curve analysis will also be reviewed. Grazingincidence diffraction, an emerging new technique, can be used to obtain structural details parallel to the interface on films with thicknesses ranging down to a few atomic layers. The synchroton has now become increasingly available as a powerful source of x radiation which will facilitate the application of conventional and grazing-incidence diffraction to ultra-thin films.

The JCFDS-ICDD based in Swarthmore, PA maintains and distributes a database of powder diffraction data. This database is widely used throughout the world by x-ray analytical laboratories for crystalline phase identification. It is the charter of that organization to update, expand and upgrade the quality of data in the database. As this work is carried out, the database is made available on an annual basis at a fee Commensurate with the committee's operation as a self-sustaining, non-profit organization.

An adapter for a standard Norelco spectrographte attachment will be described which permits the examination of a selected area of the specimen by X-ray fluorescence analysis. The size of the area can be varied depending upon the choice of pinholes with sizes available dovwi to 0.010 in. or 250μ. The sample is placed into a specially modified sample holder so that it can be moved at orthogonal directions under the beam from outside the spectrograph while the sample is under X-ray irradiation. Dam on applications will also be given.

Traditionally, clinical studies of lead's effect on health have relied on blood lead levels to indicate lead exposure. However, this is unsatisfactory because blood lead levels have a half-life of approximately 5 weeks (Rabinowitz et al., 1976), and thus reflect recent exposure. Over 90% of the lead body burden is in bone, and it is thought to have a long residence time, thus implying that measurements of bone lead reflect cumulative exposure (Barry, 1975). So, measurements of bone lead are useful m understanding the long-term health effects of lead.

X-Ray diffraction measurements of MnO confirm the hypothesis that the structural temperature and the magnetic transition temperature, or Néel temperature) are the same. The usefulness of X-ray diffraction intensity data of MnO, with respect to an atomic structural refinement problem involving α-Mn powders, is discussed. Lattice constant values of MnO are listed between 100 and 310°K

A prototype of a new high temperature chamber has been developed at our institute. Like most of such chambers it has an evacuated housing which is watercooled, and in its center a tungsten heating strip is mounted on watercooled clamps (fig.1). A special way of clamping compensates for thermal expansion automatically and thus keeps the specimen in an aligned position. The specimen is mounted directly onto the heating strip's surface. Specimens are prepared using fine powders mixed with distilled water and acetone to give a thin slurry. This mixture is put onto the heating strip and carefully dried with a heatgun. This way of preparing a specimen makes it cling to the heating strip quite well even at temperatures above 3000K and therefore provides good thermal contact.

While x-ray fluorescence spectrometry is a highly sensitive and highly repoducible method of analysing samples, its one weakness is its relatively low sensitivity for light elements. This is mainly due to two problems: firstly the low fluorescent yield of the low atomic number elements, and secondly to the inherent inefficiency of exciting these elements. While it is not possible to improve the fluorescent yield, considerable improvements in light element sensitivity can be achieved by improvements in x-ray tubes.

Improving the detection limits in TXRF by optimizing the excitation conditions is the goal of this work. The properties of the exciting radiation due to spectral distribution, polarisation, intensity and energy are investigated and compared to find best conditions. Results are given from experiments performed with synchrotron radiation, Bragg polarized monoenergetic x-rays, high energy cut-off reflector in the primary beam path of a high power x-ray tube and several geometries for the sample reflector.

Bremsstrahlung emission from four x-ray tubes operating at 12 to 300 kV was measured. Spectral distributions are given in terms of absolute-photon and energy fluxes. Silicon and germanium semiconductors, sodium iodide scintillators, and a xenon proportional counter were used to measure the spectra. Detector distortions were corrected by assuming an undistorted spectrum, distorting the spectrum with a Monte Carlo computer program, and comparing the results with measurement. The assumed undistorted spectrum was revised until the Monte Carlo calculation gave satisfactory agreement with spectral measurements from all four types of detectors. The effects on the spectra of varying the tube potential, tube current, target aperture, and detector aperture were investigated. Corrections for the intervening material and the solid angle subtended by the detector were applied to obtain the absolute-photon and energy flux from the target. Total fluxes in the L lines, K lines, and continuum are given. X-ray-production efficiencies varied from 0.026% at 12 kV to 1% at 300 kV. The constant of proportionality varied in the range (0.23 to 0.73) x 10-6 kV-1.

X-ray tubes are used extensively in energy dispersive x-ray spectrometers in preference to radioactive sources because of their high output, variable intensity and tuneable energy spectrum. Tubes for this application have certain requirements which make them different in detail from the more common radiographic or therapy tubes and this paper sets out to present a review of some of the fundamental features of modern spectrometry grade tubes.

The Digital Equipment Corporation (DEC) operating system RSX-11M has recently been installed on a DEC PDP 11/34 computer which is used for the control of, and to acquire and process data from, three X-ray diffractometers, one X-ray fluorescence analysis unit and an electron microprobe. The RSX-11M system replaced the modified DEC 1 - 8 User BASIC previously employed, thus replacing an operating system which was known in detail only to its writer by a system which is supported by the computer manufacturer. There are three major advantages in the use of RSX-11M over 1 - 8 User BASIC: an improved handling of program scheduling, the integration of the software driver for the computer - X-ray electronics interface into the operating system without a major modification of the latter, and the ability of RSX-11M to undertake concurrent execution of instrument control, data acquisition, and data reduction. The 11/34 - RSX-11M system has been implemented to use FORTRAN; a BASIC interpreter has, however, been added which allows users to interact on-line with the computer. A command interpreter which can accept a command line from a terminal has been included.

The XRF11 program by John Criss and the EXACT program are two commercially available fundamental parameters programs for energy dispersive x-ray fluorescence spectrometry (EDXRF). These programs are both based on the same underlying equations but use different approaches to the calculations. The EXACT program assumes monochromatic excitation, and the XEF11 program models polychromatic excitation sources. There are also great differences in how the two programs approach the iterations in the calculations and in how the data from standards are used in the two programs for calibration.

To produce the monochromatic excitation neeiled by the EXACT program, secondary targets have been the preferred method. But it is also possible to approximate monochromatic excitation by using filtered direct excitation. The purpose of this study is to compare the data obtained from both secondary targets and direct filtered excitation as processed through both XRF11 and EXACT.

Real time observations of the YBa2Cu3O7-δ (123) melting process by high temperature XRD and optical microscopy reveal a reaction sequence which does not correspond well with the literature. CO2 gas, present in the air, reacts with 123 to produce the Y2CU2O5 phase. This reaction begins well below 800°C and persists up to 970°C when BaCuO2 begins to form. The previously unreported BaCuO2 reaction occurs in either air or oxygen and this phase grows at the expense of the 123 until both rapidly disappear at 1050°C with the appearance of Y2B2CuO5 (211), Formation of Y2O3 from the 211 melt occurs more slowly, beginning at 1150°C. Dynamic 00ℓ orientation has been observed at 950°C upon cooling from the melt. The orientationa) growth is believed to be a surface tension dependent, liquid assisted sintering reaction.

When an x-ray diffraction profile Is measured for stress analysis or profile analysis by the use of a linear (straight line) position sensitive proportional counter (PSPC) , a convex-type background line is obtained because of the geometrical problem and the absorption of x-rays. Such phenomenon is remarkable when a wide angular range is set on a linear PSPC and it is, in particular, necessary to correct with a straight background for accurate measurement of diffraction angle or half-value breadth of the broadened diffraction profile.

Two new methods of comparison of lattice parameters are described. The first method uses a double crystal diffractometer, fitted with a specimen rotation stage. Bragg peak positions of a silicon reference and the specimen crystal are recorded for the crystals at 0 and rotated 180° about the diffraction vector. From the mean Bragg positions the lattice parameters can, in principle, be compared to parts in 106. The second method is a variant on the above, using a triple axis diffractometer. It uses a beam conditioner and monochromator to define the incident wavevector ko, and an analyser crystal to define the diffracted wave vector kh. Only the analyser motion must be accurate and stable to the arc second level. We present a detailed error analysis for the case where reference and specimen Bragg angles differ significantly. Peak location to a confidence level of 1 arc second permits absolute, traceable lattice parameter determination to several parts in 106.

Accurate phase characterization of the alteration products of rad-waste requires the separation and identification of scattered individual grains from among the bulk product. These grains are typically 5 to 100 μm in size. Bulk x-ray powder diffraction will normally not detect these minor phases, and even if the phase can be detected, it often may not be identifiable. The use of the Gandolfi technique with the individual particle not only facilitates the identification, but also allows the assignment of the identification to the specific grain.