X-ray diffraction studies were performed on ammonium fluoroborate [NH4BF4], ammonium perchlorate [NH4ClO4], ammonium chloride [NH4CI] and ammonium phosphate [(NH4)H2PO4] within a temperature range of ambient to −190°C. For these experiments a specimen holder was designed to effect rapid cooling of the sample. Results indicate that the fluorob orate and perchlorate salts undergo a polymorphic transition at −190°C. The decreasing intensities of the (011) and (112) reflections of the orthorhombic modification indicates a firstorder reaction. No transition was observed when these salts were cooled to −40°C. The ammonium chloride shows a transition at about −30°C which confirms the results obtained by G. H. Goldschmidt and D. G. Hurst. The ammonium phosphate (NH4)H2PO4, which is tetragonal at ambient temperature also undergoes a transition if cooled to −190°C. The kinetics of this reaction are discussed.

In this study, X-ray diffraction analysis is used to investigate the composition of aerosols produced by exploding wires with the current surge from a 4000-joule capacitor. Qualitative analyses of aerosols from 15 different metals exploded in air or inert atmosphere indicate that the particles are crystalline with the normal crystal structure and that explosion of noble metals in air and of base metals in argon produces aerosols consisting of metallic particles. Base metals exploded in air produce aerosols consisting primarily of oxides. Nitrides were not observed. An analytical scheme is described for the Cu-Cu2O-CuO mixtures collected on membrane filters from explosions of copper wires in air. The composition of aerosols is determined for various initial voltages (2-18 kv) on the 20-μf capacitor bank for two series of wires. In one, the weight fraction of CuO increases rapidly with voltage until it accounts for almost the entire sample while the Cu2O and Cu content decrease smoothly. In the other, CuO and Cu2O are about equal for explosions above 6 kv while Cu decreases. Differences are attributed to a change in the circuit and mass of wire used.

Preferred orientation in polymers has been studied by preparation of pole figures. The diffraction data are collected on punch tape under the control of a programmer for the orienter which permits step wise or continuous scanning. A computer is programmed to prepare the data for an off-line automatic curve plotter. Several projections are available.

From pole figure data, the orientation of a crystallographic direction R in any reference direction Q in a sample can be quantitatively expressed by the average <cos2σ>, where σ is the angle between Q and R in a crystal. In general, <cos2σ> can be evaluated in terms of the experimental averages <cos2ϕhkl> whereϕhkl is the angle between Q and the normal to the (hkl) planes. The number of independent <cos2ϕhkl> measurements needed varies from one to five depending on the crystal system, hkl indices, and other factors discussed. Experimental techniques found useful for measuring <cos2φ> are described.

Using an X-ray diffractonieter cryostat, the lattice constants of the isotopes 20Ne and 22Ne as well as the naturally occurring mixture have been measured throughout most of the temperature range in which they exist as solids (0 to approximately 24°K), The heavier isotope has the smaller lattice constant, the values obtained at 4.2°K being: 20Ne—4.4624 Å, 22Ne—4.4540 Å, and 11Ne—4.4622 Å. The absolute error in these values is believed to be no greater than 0.001 A. The volume expansion coefficient, which does not appear to differ significantly in the three cases, increases to a value of 6.3 × 10−3/°K at 24°K.

The adaptation of high-frequency heating techniques to a vertical diffractometer will be discussed. The heating system functions as a. portion of an integrated system that provides a wide range of atmospheric and temperature control. Some of the design problems and their solutions and operating characteristics of the system will be described. The useful temperature range is from less than 200°C to greater than 1600°C, depending upon the fur-nace atmosphere and susceptors used. Gaseous pressures may be from vacuo of about 10−6 mm to about 30 psia; and, the sample may be heated in oxidizing, neutral, or reducing atmospheres.

This paper presents some of the physical considerations which must be considered in operating an X-ray generator to obtain maximum stability and reproducibility of intensity measurements. In addition, a typical X-ray generator will be discussed from the standpoint of enabling the user to realize all of the stability and reproducibility capabilities which were designed into the equipment.

Detailed EMX specifications are presented. Performance data obtained on several production instruments are discussed and some future applications of microprobe analysis are suggested.

The electron-pro be analyzer has been developed in a period of thirteen years to a point where several different instruments are commercially available and about one hundred are already in use. At the present time it is possible to analyze volumes of about 1 μ3 at the surface of a specimen for elements above sodium in the periodic table with a concentration sensitivity of the order of 0.1-0.01%. New developments in the field include efforts to extend the range of Z to lower atomic numbers and to increase the spatial resolution of the method so that smaller volumes niay be analyzed. Progress in the analysis of the light elements centers at present mainly on the use of nondispersive detectors and. computer techniques for the resolution of overlapping pulse-height distributions. With such methods qualitative detection of elements down to beryllium has been achieved in the presence of their near neighbors. Efforts to increase the spatial resolution of the probe have led to the use of thin specimens which are partially transparent to electrons. Partly as a consequence of this approach, apparatus has been developed in which an electron microscope with facilities for selected area diffraction has been combined with an electron-probe analyser. The ever-widening range of application of the electron-pro be technique has inevitably disclosed problems in the interpretation of quantitative data, and it is clear that at the present time more information on the process of X-ray production by electrons is required before semi-empirical methods can be entirely eliminated. Examples of the use of the method in metallurgical and mineralogical studies illustrate some of the current trends in the refinement of measurement technique and interpretation of experimental data.

In view of the amount of data per time unit the scanning electron probe is capable of producing, time economy in data presentation is of great practical importance. In this paper, the characteristics and advantages of various previously known techniques of data presentation are described, and some novel procedures are proposed.

Applications of filters are routine and useful techniques in X-ray diffraction and.can also be useful in X-ray spectrography to improve analytical results with very simple procedures. Fankuchen demonstrated the use of filters over the window of the X-ray tube to minimize background from the target element and/or elements in other components of the X-ray tube in research programs at the X-ray- Laboratory, Metallurgy Division, Denver Research Institute during the summer of 1952. This general procedure has been adapted to routine analyses by modification of the spectrograph to provide for movement of filters in and out of position between the window of the X-ray tube and the sample while the instrument is in operation. Placement of filters in the X-ray beam path of the spectrograph between the sample and the analyzing crystal is also a useful procedure to reduce interferences by elements exhibiting lines at closely adjacent wavelengths.

Three basic methods for the daily use of the X-ray spectrograph are presented with the object of demonstrating simplicity of operation, reliability of results, and ease of use of the basic Norelco X-ray spectrograph by personnel not highly trained in the operation of such equipment. The methods to be outlined briefly are: (1) Determination of calcium fluoride in reduction cell electrolyte; (2) Analysis of cast iron for Si, P, Mn, S; find (3) Analysis of carbon materials for S, K, Ca, V, Mn, Fe, and Ni. The mechanics of the methods will be outlined with the reasons for their selection, and the operating and maintenance problems which have been encountered will be discussed.

A vesta Steel Works manufactures stainless steel, low-alloy steel, alloys for precision casting, welding electrodes, and ferro alloys. When it was decided in 1958 that a new laboratory for production control was to be built, there was an investigation into different spectrographic possibilities. A combination of X-ray and optical methods was selected, that is, determination of C, P, and S was to be made optically while Si, Ti, and heavier elements were to be determined on X-ray equipment. Specimen taking and specimen preparation techniques were worked out. Certain interelement effects were recorded and methods to correct for them found. Methods to. correct for surface properties in determination of high concentrations have been taken into use. This laboratory has now been in continuous use for more than two years. Statistical data on accuracy, reliability, and continuity of operation are given.

Aluminum, is determined within the range 2-16% in iron. Repeatability of X-ray determinations is within a standard deviation of 0.07 % aluminum for a sample containing 10.2% aluminum. The standard deviation of the chemical values from the straight line calibration curve is 0.3% aluminum. X-ray analytical time is approximately 5% of the time required for chemical analysis. Peak-to-background ratio is improved by using a chromium-target thin-window X-ray tube instead of a tungsten tube.

The measurement of the area density of zinc coatings on steel by X-ray fluorescence is considered from an instalment design point of view. Each of the two general approaches, i.e., measurement of the attenuation of the iron emission line by the zinc coating and measurement of the sine emission line has limitations. Calculations indicate that contrast requirements are best satisfied by the iron attenuation technique in the coating weight interval 0.2-1.2 oz/ft2 per side. Experimental data collected on galvanised and zinc foil samples are presented in support of this contention. Conversely, advantages in the application of the zinc emission method to very thin zinc coatings are pointed out. Spectral resolution is discussed in terms of the ultimate precision and range of coating weight measurements. For the iron attenuation method, it is concluded that a black plate to infinite zinc intensity ratio of approximately 500 permits reasonably precise measurement of zinc foil coating weights in the vicinity of 1.2 oz/ft2 per side. This requirement can be met through the use of a LiF monochroraator crystal and 5 in. of effective 0.020-in. flat plate collimation.

The paper is divided into two parts. The first section presents a review of three basic methods of X-ray spectrochemical analysis, including the internal standard method, the absolute intensity method, and the ratio method. The applications and limitations of each are discussed briefly. The second section presents the ratio method at length. Included are the methods of acquiring standards, sample preparation, curve plotting, and a discussion of the factors contributing to the precision of the analysis. Various analytical curves are presented and discussed and the sensitivity for minor constituents is shown.

As is well known, the fluorescent yield decreases very rapidly with the atomic number with the result, for example, that sensitive sodium and magnesium analysis is extremely difficult if not impossible with conventional X-ray spectrographs. It is demonstrated, however, that analysis for sodium and magnesium can be accomplished with sensitivity comparable to that conventionally obtained for elements such as aluminum, silicon, and phosphorous, providing that the conditions for excitation and measurement of the associated soft X-radiations are optimized, A high-intensity demountable tube using an aluminum anode has been developed which can be used interchangeably with the conventional spectrographic X-ray source. This provides a large amount of incident radiation, aluminum foil filtered, optimally close in wavelength to that of the line radiation being excited. A gypsum analyzing crystal is used along with greatly reduced beam collimation. The standard flow proportional counter and pulse height discrimination is employed. An appropriate filter, such as aluminum foil, is used as a window for the counter1 to provide further discrimination and enhanced signal-to-background ratio.

Moderate counting rates, in excess of 400 cps at a signal/noise ratio of 18 on 3.5% NaaO in rocks, permit high-precision quantitative analysis for light elements in silicates. Special advantages of fluorescence analysis in the 10 A region, with adequate excitation provided by an aluminum target tube, will be described. These advantages include an ease of discrimination by excitation potential and by high dispersion using large 2d space crystals. Minor and simple modifications of the optic path combined with electronic discrimination make the method ideal for sodium and magnesium. Routine runs over periods of days have been made possible by a new technique of calibration involving computer corrections for systematic drift from any source. Repeated tests show that the total analytical error, including specimen preparation, closely approaches that of the counting statistics used, and that the drift corrections are complete. In granitic rod; analyses resulting precisions (standard deviation/mean) are 1% for 2-5% Na2O and 2% for 0.25-1.0% MgO.

Analysis schemes for eleven rare earths (Ce, Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb) taken singly in Y-Fe garnet powders are presented. Straight-line calibrations result in all cases, usually over a range from below 0.5 wt.% to better than 6 wt.%. Errors were held to ±5-10% even using extraordinarily simple sample preparation techniques. Data are presented relating to the effects of particle size and sample preparation on precision and accuracy of the resulting analysis.

A Norelco Autrometer (automatic multielement X-ray spectrograph) is being used by a petroleum refinery control laboratory for process control and product quality control. As many as 100 analyses covering 13 elements are run per day. Concentrations range from a few ppm to 25%.

The instrument has reduced the elapsed time for many analyses from 8 hr to 5 min, made possible in many cases greater accuracy than previously used wetchemical methods, reduced laboratory manpower and increased refinery production efficiency in many instances.