The homogeneity of solid solutions of cadmium selenide and cadmium sulfide has been investigated. Crystals of the solid solutions having different selenium contents were grown in the Aerospace Research Laboratories by the conventional methods as described in the earlier conferences. The composition of these solid solutions were analyzed chemically for their selenium content by a procedure perfected in the Aerospace Research Laboratories.

Crystals in the form of lumps were cut to optimum size suitable to be inserted into the commercially available sample holder. The selenium content of these crystals was ascertained by scanning the samples with stationary colljmators of small aperture. The spectrograph used for the present study was operated at 75 KVP and 50 mA. The target tube was constructed of molybdenum. The results from the chemical method were used to correlate the counts per second obtained from the X-ray spectrograph.

The effect of temperature change on LiF, ADP, and EDDT analyzing crystals was studied by measuring the change In intensity of a selected X-ray spectral line while maintaining a constant 2θ position on the spectrometer. A change in interplanar spacing due to thermal expansion and contraction satisfactorily account for experimentally observed line shifts for LiF and ADP. EDDT showed a large unexplained decrease in reflectivity with increasing ambient temperature.

An equation was developed to express the change in intensity at a constant 2θ position as an exponential function of temperature. In this equation the thermal expansion coefficients of the principal axes of the crystal, the width of the spectral line at half-height, and the Bragg angle appear as factors. Intensity changes due to peak shift were tabulated for LiF, ADP, NaCl, silicon, germanium, quartz, calcite, fiuorite, and topaz.

A rapid method for the determination of rubidium in cesium metal by X-ray fluorescence is described. Cesium metal is converted to the chloride, and pellets are pressed with molybdenum trioxide as an internal standard. The rubidium to molybdenum intensity ratio is used to eliminate the effect of small amounts of the other alkali metals. The analytical curve is linear from 0.05 to 15% rubidium, which covers the range of samples normally encountered. Rubidium can be determined with a coefficient of variation of 1.3% in this range. Good agreement was shown with results obtained by flame photometry.

Since the advent of vacuum and helium path X-ray spectrometers, and flow proportional counters, the determination of low-atomic-number elements by X-ray fluorescence has become relatively common for light-element matrices. However, there are no reports in the literature on the determination of the low atomic-number elements in a rnatrix approaching that of uranium. This paper describes the successful application of the vacuum path X-ray spectrometer for the determination of calcium in the range of 0.03 to 1.75% (on a U3O3 basis) in uranium ore concentrates. The procedure provides a 50% saving in analyst time, with no sacrifice of accuracy or precision, compared to the chemical method previously used. With a chromium target tube, the intensity of the calcium radiation is quite sufficient for accurate analyses even though the samples contain approximately 80% uranium. The heavy uranium matrix actually serves to minimize any absorption or enhancement effects that would normally be expected from the large number of impurities that are present in widely varied concentrations.

Samples are prepared by dissolving 1.8 g of concentrate in 10.0 g of Na2B4O7 at 1050°C and casting into a disk on a polished aluminum plate. The advantages of this preparation compared to the use of pelletised powders will be discussed. The Ca Kα-to-U Mγ ratio is used to minimize the1 effect of instrumental and sample variations and to provide a linear relation with respect to the calcium concentration on a U3O8 basis. Calibration standards are prepared by the addition of CaHPO4 to either pure U3O8 or a uranium ore concentrate of low residual calcium. Data obtained during routine application of this procedure will be presented.

The application of X-ray fluorescence to the qualitative and quantitative analysis of chemically modified cotton textile materials is described. The scope and flexibility of the technique have permitted the determination of more than 20 elements with, greatly reduced elapsed time compared with the corresponding spectroscopic or wet methods. Precautions to be observed in preparing standards are discussed. Results of the analysis of typical modifications and their significance in the development of cottons for specific uses are described.