Geiger Counter Spectrometer Research Articles

Geiger Counter Spectrometer for Industrial Research

X-ray diffraction has many applications in the chemical and metallurgical industries, but its techniques have been confined until recently to the laboratory and to highly trained personnel. Conventional procedure entails photographic exposure, processing, and density comparisons of the finished film strips.The Geiger counter spectrometer described below measures x-ray intensities and diffraction angles directly, without intermediate photographic steps. It is simple enough for unskilled operators performing routine industrial processes yet also meets the precise requirements of laboratory research. The instrument was developed at the Naval Research Laboratory, where it has been in regular use for the past two years.

X-ray diffraction profiles from deformed metals

Pure diffraction profiles have been obtained for several reflections from cold worked and partially annealed samples of spectroscopically pure aluminium and copper and four alloys containing aluminium and copper. Intensity distributions were determined with the help of crystal monochromated copper Kα radiations and a Geiger counter spectrometer manually operated and provided with scalars and dekatron counters. The observed line profiles were corrected for Kα2 overlap, thermal diffuse scattering, Lorentz and polarization factors, absorption and background error. A method has been developed for correcting for the background level from multiple measurements of the integral breadths of the line profiles at several assumed background levels. From the corrected line profiles, pure diffraction line profiles were recovered by the method due to Stokes. The R(x) test described by Mitra when applied to these pure diffraction profiles showed that none of them belonged to either Cauchy or Gauss type. Since many experimental R(x) curves were found to terminate at about x = 2, another function, the R'(x) function, has been developed. This function assumes the theoretical curves also to be truncated at the same ranges as the experimental curves. R'(x) tests also showed that the pure diffraction profile was neither of Cauchy nor of Gaussian type. The parameter γ = μ4/μ22, μ4 and μ2 being fourth and second central moments respectively of the profiles, has been evaluated for all the curves, and comparison with standard statistical tests showed that most of the curves belonged to Pearson types VII and IV while some might also be Gaussian. The results indicate that the intensity distribution curves can be expressed in terms of a maximum number of four unknown parameters and hence determination of the first four moments only is expected to lead to the proper expression for the line profile.

Release of lattice energy and annealing of dislocations in deformed silver

Measurements of the changes in intensity distribution have been made, using a Geiger counter spectrometer, in the spectra of cold worked silver. An attempt has been made to interpret the Fourier coefficients of pure x-ray diffraction line profiles by assuming Gaussian as well as Cauchy strain distributions. Finite values of domain sizes and lattice strains have been obtained in both cases. Except at room temperature, where a twin fault probability β equal to 0.01 is obtained, the composite broadening in each case has been attributed partly to strain and partly to small particle size. From a study of the variation of particle size with temperature, recovery and recrystallization stages have been clearly identified. Observations on annealing of dislocations support the recent electron microscope observations that dislocations are arranged in a cell structure.

Mosaic Size in Lead from X-Ray Measurements

The size of mosaic blocks in lead powder was determined on the basis of the primary extinction effect of x rays. Integrated intensities of nine reflection lines in the Debye-Scherrer spectrum with CuKα radiation were measured with a Geiger counter spectrometer. The mosaic size was calculated by comparing these values with theoretical values of the intensities. Correction for absorption of x rays in the specimen powder was especially important because of the large absorption coefficient of lead. The order of magnitude of the mosaic size was found to be 10−4 cm. From this value, the dislocation density was calculated to be of the order of 108 cm−2. The dislocation density decreased slightly when the specimen was annealed in vacuo at 150°C for a long time.

Investigation of the annealing of nickel deformed by compression by X-ray and stored energy measurements

Abstract X-ray diffraction patterns from bulk specimens of nickel deformed by compression have been measured with a Geiger-counter spectrometer. A composite specimen has been used to overcome the effects of preferred orientations. The results indicate that during the annealing there is no change in the background intensity. No evidence has been found for stacking faults or changes in lattice parameter. The integrated intensities of all lines remain constant up to a temperature of annealing of about 480[ddot]c. A large decrease (30–75%) in the integrated intensity of all lines occurs on annealing to 600[ddot]c and this is attributed to extinction; an estimate of 2–4 μ is obtained for the size of the 'perfect' regions required to produce this effect. The diffraction profiles are analysed by a number of methods. The broadening produced by the particle size effect is small. The stored energies derived from the various methods of analysis range from 0.04-2-4cal/g. Best agreement is obtained between values of s...

Development and Comparison of Two X-Ray Methods for Determining the Crystallinity of Cotton Cellulose

Two x-ray methods have been developed for determining the crystallinity of cellulose using a Geiger counter spectrometer. The two methods were applied to six native cotton varieties, to a cross-bred variety, and to two cottons chemically modified with ethylamine. The x-ray scattering curves for each of the nine samples were compared with those from a highly crystalline sample, a cotton hydrolyzed in HCl, and an amorphous cotton sample to provide a relative measure of crystallinity, or crystalline index. With fully corrected data the average crystalline index of the six cotton varieties was found to be 68.3 and 78.7% by the correlation and by integral methods, respectively. The crystalline indices of the remaining samples determined by the correlation and by the integral methods are, respectively, cross-bred cotton (S×P), 54.3 and 77.2%; cotton treated with anhydrous ethylamine, 29.7 and 50.9%; and cotton treated with 75% aqueous ethylamine, 28.3 and 50.3%.

Cross-rolling and annealing textures in high-purity iron

The deformation and annealing textures of cross-rolled high-purity iron specimens were determined by use of an X-ray Geiger counter spectrometer. The deformation texture was predominantly (100) [011], plus minor texture components of the (111) [110] or the (111) [112] type. In a partially recrystallized specimen, the minor deformation texture components were replaced by new orientations, while the (100) [011] main deformation texture was retained. A rather complex and widely scattered texture was developed in the completely recrystallized specimen. This recrystallization texture could be derived from the deformation texture components by rotations around (110) poles. The difference in the tendency for recrystallization among different deformation texture components may serve as an important factor in the formation of annealing textures.

Investigation of the annealing of deformed nickel powder by X-ray and stored energy measurements

Abstract The stored energy was measured by a calorimetric method. The measured value of 3.6 cal/g and the manner of its release suggests that a wide range of deformations is present, both the maximum and average deformations being considerably greater than those present in heavily deformed solid specimens of nickel. The diffraction patterns, measured with a Geiger counter spectrometer, show that during annealing there is no change in the background intensity. The integrated intensities of the high angle lines remain constant and small changes in the low angle lines are attributed to changes in extinction. Only small changes occur in the tails of the lines at temperatures of annealing up to 400°C. No evidence has been found for stacking faults or changes in lattice parameter. The diffraction profiles are analysed by a number of methods, the broadening in each case being attributed partly to strain and partly to small particle size. The results indicate two stages in the relief of strain. The first occurs m...

A Method for Obtaining a Quantitative Pole Figure of Stretched Rubber

AbstractWork at the Detroit Arsenal has shown that techniques similar to those employed for the determination of pole figures of metals can be utilized for studying organic materials such a a stretched rubber latex. The rubber, when stretched, forms a preferred orientation pattern which is proportional in intensity to the degree of elongation, and which can be used to plot a pole figure.A Geiger-counter spectrometer was used to study samples of rubber stretched 600 to 1000 per cent. Using a transmission technique, the specimens were tilted to the impinging X-ray beam in five degree increments while rotating through 360 degrees to allow the measurement of the diffracted beam from the selected atomic planes at various angles within the specimen. The intensities of the diffracted beam at these angles were plotted on a stereographic net to form the pole figures of the (002) and (012) planes of the stretched rubber. The geometry of the sample arrangements permitted the outer portion of the pole figure to be plotted from alpha angle 0 degrees to alpha angle 45 degrees.

X-Ray Study of the Local Atomic Arrangement in Partially Ordered Cu3Au

The atomic arrangement present in Cu3Au in a state of equilibrium partial long-range order has been investigated by measuring with x-ray techniques the short-range order existing below the critical temperature. A single crystal of Cu3Au, cut parallel to a (100) face was quenched into water from 380°C, just below the critical temperature for ordering. Using monochromated Cu Kα radiation and a Geiger counter spectrometer, the diffuse scattering from this crystal was measured in the (h1h20) plane of reciprical space. From these data, short-range order parameters and a first-neighbor size effect coefficient were obtained. The measurements show that there is a marked short-range order among the wrongly occupied sites below the critical temperature. It is shown that the measured short-range order parameters can be predicted by assuming that the wrongly occupied sites coalesce into tiny antiphase domains, and that these domains are one atomic plane in thickness, lie parallel to any one of the three sets of (100) planes in the crystal, and contain, on the average, about nine atoms each.

A New Alumina Trihydrate

DURING the development of a platinum-alumina catalyst, X-ray studies have revealed that, in addition to the well-known gibbsite and bayerite, a third crystalline form of Al(OH)3 exists. Pure samples of this new trihydrate have not been obtained. It is generally accompanied by bayerite, often by both bayerite and gibbsite. In samples where this new crystalline trihydrate is the major component, it has been possible to determine its chemical composition as Al(OH)3 and to resolve its X-ray diffraction pattern. This pattern of the new phase (as recorded with a Geiger counter spectrometer using copper Kα radiation) is:

Preferred Orientations in Rolled and Annealed Titanium

Preferred orientations in rolled and annealed titanium sheets were determined by the Geiger counter spectrometer X-ray diffraction technique. Five annealing textures dependent upon the temperature range of annealing were found, and in order of increasing annealing temperature are: 1—a deformationlike texture, 2—a rotated a-recrystallization texture, 3—a retained a-recrystallization texture on annealing at lower temperatures of the β-region, 4—a transformation texture based on recrystallized a and predicted by the Burgers’ relationship, and 5—a β-cube texture. These results are examined in terms of current theories of recrystallization textures.

The study of the elastic constants of white tin by diffuse X-ray reflexion

Tin crystals were grown by lowering a tube containing the melt through a vertical furnace, at a rate of 5 mm.hr.-L Crystals obtained were spherical or cylindrical of diameter about 2 em. Faces parallel to (100), (110) and (103) were cut with a chisel or microtome. The surface imperfections were removed by electrolytic polishing. The diffuse reflexions from regions of reciprocal space surrounding the reciprocal points 400, 440 and 103 were investigated using a Geiger-counter spectrometer. The results were: c n ----8.6, caa = 13.3, c44 = 4.9, c66 ---5.3, c12----3-5, c13----30×10 n dyne. era.-, the estimated accuracy being 7 %. The values for caz, c44, c6~ and c~2 differ considerably from previous values given by Bridgman. A noteworthy feature of the diffuse reflexion was the backgrotmd intensity. Although this did not interfere with the measurement of the elastic constants, it indicates the presence of diffuse refle.vion due to some other cause than that which is associated with the long acoustic waves.

X-Ray Measurements of Particle Size and Strain Distribution in Cold Worked Silver

X-ray diffraction profiles from filed solid silver specimens were measured with a Geiger counter spectrometer using crystal-reflected Cu Kα radiation. It is shown that for values of n>7, the assumption of a Gauss strain distribution fits the observed Fourier coefficients far better than a Cauchy distribution. The results obtained from solid specimens are consistent with those previously measured for silver filings. The influence of background errors is discussed.

Integrated X-ray intensity measurements from a solid solution of copper–gold

In a solid solution random displacements of the solute and solvent ions from the mean crystal lattice are produced by the elastic strkins associated with their different sizes. A prediction of the effects on the X-ray spectrum is based on a model which treats the solute ions as centres of dilation in a finite isotropic elastic continuum. The resultant theory shows that the addition of solute atoms produces a mean lattice parameter change upon which are superimposed random displacements of the ions. These displacements result in a decrease in the integrated X-ray intensities of the high-order diffraction lines of the form associated with thermal vibrations. The effect is particularly marked in the copper-gold solid solution and comparison of the measured X-ray intensities from copper and a 15 atomic % solution of gold in copper enable one to deduce a value for the root mean square displacement ~/(~) due to distortion, when that due to thermal vibration has been allowed for. Measurements of the X-ray spectra were made using a Geiger-counter spectrometer from which it is deduced that ~/(~2) = 0.11 ~. This value compares favourably with the value predicted from the elasticity theory, namely V(~ ~) = 0.13 A.

Preferred Orientations in Beta-Annealed Zirconium

Preferred orientations in unalloyed zirconium were determined by the Geiger counter spectrometer X-ray diffraction technique. With increasing β-annealing temperature the following textures were obtained: 1—a retained α-annealing texture, 2—additional orientations predictable from the α-β (Burgers) relationship, and 3—a texture derived from a cube texture in the β phase. Earlier work on cold-worked and α-annealed zirconium was reappraised to show a quantitative dependence of rotations on temperature and to identify spurious areas of some of the pole figures.

X-ray measurements on silver filings

A Geiger counter spectrometer, with crystal-reflected CuKα radiation, is used to determine the shapes and breadths of the X-ray diffraction profiles of filings from high purity (99.999 per cent) and electrolytic (99.6 per cent) silver. Because the filings recover rapidly at room temperature, the observations are made on specimens kept at− 30°C. From the Fourier coefficients and breadths of the diffraction profiles, particle size and strain values are calculated. Normal strain values are found and particle size values of the order of 200 Å are obtained. No experimental evidence is found for the presence of stacking faults in plastically deformed silver. Curves illustrating the rate of recovery (increase in intensity with time of a profile maximum) of two specimens filed under different conditions are given.

X-ray measurement of order in CuAu

The long-range order in CuAu has been measured with a Geiger counter spectrometer using filings quenched from various annealing temperatures. The long range order is essentially perfect at low temperature, and decreases to about 0.97 at 380°C, where the material changes to CuAuII. Short-range order coefficients were determined from measurements of the diffuse intensity from a single crystal of CuAu. The coefficients indicate a preference for unlike nearest neighbors, and they are qualitatively similar to those for Cu 3Au. An outward shift of the 100 and 300 diffuse peaks suggests but does not prove the existence of a microlayering, similar to CuAuI, even above the critical temperature.

Preferred orientation in α-uranium

The preferred orientation of uranium rolled in the α-range has been investigated by X-ray diffraction using a spherical specimen in the Geiger counter spectrometer. Complete figures of the principal pole distributions have been obtained without absorption correction. At low rolling temperatures, a texture is obtained having principal pole maxima corresponding to a single unit cell orientation. The (001) and (100) pole maxima lie in the plane normal to the rolling direction at 30 and 60 degrees respectively to the compression axis; the (010) pole maximum is parallel to the rolling direction. At higher rolling temperatures near the recrystallization point a duplex texture is obtained, having a common (001) pole maximum at 20 degrees to the compression axis, and having the (010) and 110) poles parallel to the rolling direction. The unit cell probability distribution has been derived using two principal pole distributions, and from this the inverse pole figures have been calculated, giving the distributions of the compression axis and of the rolling direction over the unit cell. A direct comparison of the rolling figures predicted by Calnan and Clews is obtained from the inverse pole figures. Good agreement is obtained with the figures predicted for rolling at low temperatures where deformation occurs predominantly by twinning with a small amount of slip. The rolling figures obtained at high temperatures giving the duplex texture are not in agreement with Calnan and Clews. A treatment of the deformation of α-uranium during tension, compression and rolling is described, using the glide mechanisms determined by Cahn, which is compatible with both the low- and high-temperature textures. The reorientation of the (010) axial and the duplex (010)-(110) axial textures upon recrystallization has been investigated. The (010) texture is shown to be relatively stable under recrystallization. The duplex texture undergoes reorientation to give a single component texture having the (151) pole axial. A (100) pole maximum occurs along the rolling direction which is shown to be due to overlapping of four symmetric components.

Elastic Spectrum of Zinc from the Temperature Scattering of X-Rays

The temperature diffuse scattering of x-rays from a single crystal of zinc has been measured at room temperature using a Geiger counter spectrometer and crystal monochromated Cu $K\ensuremath{\alpha}$ radiation. The theory of Born, together with Begbie's theory of lattice dynamics for a hexagonal crystal, was used in the interpretation. A method was developed to separate the contributions to intensity from the acoustical and optical bands. Frequency curves for the six modes of vibration propagating parallel to the ${b}_{3}$ axis, and for the six modes propagating parallel to the ${b}_{2}$ axis were obtained. Measurements were in agreement with theory for long wavelength acoustical modes, but for shorter wavelengths the first neighbor theory was not in agreement with the measurements. Approximate values for seven of the eight nearest neighbor force constants were obtained, and these values could be used for the calculation of an approximate frequency distribution curve.