Joint committee on powder diffraction standards download

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Data on the Go. Enhance Your Benchtop Performance. Comprehensive Mineral Collection. International Centre for Diffraction Data, - Science - pages. From inside the book. What people are saying - Write a review. Powder X-ray Diffraction XRD is one of the primary techniques used by mineralogists and solid state chemists to examine the physico-chemical make-up of unknown solids.

The jmol version is located here. X-Ray Powder Diffraction. Need an account? Click here to sign up. Download Free PDF. Joint Committee on Powder Diffraction Standards. Jefferson Creek. A short summary of this paper.

Lucite, were used. Samples containing no internal standard 4. For the bromide, however, it was necessary to esti- were then scanned, following alignment on the line mate the 2 0 angles of the key lines, , , , of the bromide, to provide complete interplanar spacing , and , to the nearest 0.

Integrated intensities were obtained able agreement between calculated and observed inter- from the diffractometer recording chart by counting planar spacings. Attempts to grind the crystals to a cell volume is The best value that can be placed on the were not successful.

The crystals were completely dehy- measured density is 2. It proved to be impossible to grind the crys- 4 Sorrell, C. Data, 19, 31 Received for review March 27, Accepted June 5, Vapor Pressure of Methanol from Frank Gibbard1 and Jefferson L. Other materials diffract X-rays less efficiently and yield diffraction patterns of measurable intensity only when they constitute a major portion of the sample.

As a result, certain minor constituents cannot be identified by XRD alone. For example, many of the feldspars have suffered minor incipient alteration, which manifests as small features in the Beckman spectra for example, the sharp feature around 2.

No alteration products were identified by XRD in the Sanidine sample. The problems associated with the detection limits of XRD analyses are discussed in detail in Klug and Alexander Chemical composition data were acquired by electron microprobe analysis for some of our minerals known to deviate significantly from idealized end-member compositions. Chemical compositions were obtained from polished grain mounts in the wavelength dispersive mode by using 15 keV accelerating potential, 1.

Compositionally well-characterized silicate minerals from the U. Raw data were reduced according to the ZAF correction scheme Henog et al. Hemispherical reflectance measurements in the visible and short-wavelength region of the electromagnetic spectrum 0.

The Beckman UV incorporates a single-pass monochromator and utilizes a diffraction grating as its dispersing element. The sampling interval is. Our instrument has been modified with an integrating sphere rotated 90 degrees, which facilitates measurement of powdered samples and soils by allowing the materials to remain in the sample holder in a horizontal position.

For reflectance measurements, the size-sorted samples were poured into aluminum sample holders that measured 3. The upper surface was carefully smoothed with the edge of a stainless steel spatula. Smoothing with a spatula may compact the sample and introduce some preferred orientation of grains. However, every effort was made to minimize these effects.

The sample was then placed in the sample compartment where it and a Halon reference standard were illuminated alternately by monochromatic radiation from a high-intensity halogen source lamp. Halon, a trade name for polytetrafluoroethylene powder, has been shown to be a good diffuser of incident radiation over the spectral range of the 0. However, Halon does have a small absorption feature near 2. This feature is manifest in spectra with a high reflectance in the 2.

In order to correct this Halon artifact, the spectra were multiplied by the reflectance of Halon vs a perfect diffuser given in Weidner and Hsia The correction largely removed the influence of the Halon absorption feature in our spectra.

Adams, J. Filice , Spectral reflectance 0. Karr, ed. Berry, L. Thompson , X-ray powder data for ore minerals: the Peacock atlas, Geol. Memoir, Borg, I. Smith , Calculated X-ray powder patterns for silicate minerals, Geol. Brindley, G.

Brown, eds.