Mineral phases and element composition of the copper hyperaccumulator lichen Lecanora polytropa

2008 ◽  
Vol 72 (2) ◽  
pp. 607-616 ◽  
Author(s):  
O. W. Purvis ◽  
B. Pawlik-Skowrońska ◽  
G. Cressey ◽  
G. C. Jones ◽  
A. Kearsley ◽  
...  
Keyword(s):  
Usnic Acid ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
Southern Sweden ◽  
X Ray ◽  
Mineral Phases ◽  
Position Sensitive ◽  
Metal Oxalate ◽  
Crystalline Aggregates ◽  
Non Destructive

AbstractMineral phases and element localization were investigated in the vivid turquoise-coloured lichen, Lecanora polytropa, sampled from a psammite boulder in a wall supporting mine spoil at the abandoned copper mine, Riddarhyttan Kopparverke, southern Sweden. Normally pale yellowish (usnic acid), the lichen is turquoise coloured internally with bluish inclusions. X-ray mapping shows that Cu occurs on and within the lichen and does not coincide with P or S, suggesting that it is indeed associated with carbon or other elements not detected (or reported) using X-ray mapping. Scanning electron microscopy in back-scatter mode confirmed that the greatest Cu concentrations occur in the form of crystalline aggregates in coloured inclusions below the major internal turquoise layer with smaller Cu contents. X-ray diffraction with a position-sensitive detector (XRD-PSD) confirmed coloured crystalline aggregates consisted of the copper oxalate, moolooite. The study confirms the value of XRD-PSD as a non-destructive tool to characterize small (~50 μm) metal oxalate inclusions obtained from within lichen samples.

Control of the phase composition of advanced calcium phosphates using an x-ray diffractometer with a curved position-sensitive detector

2020 ◽  
Vol 86 (6) ◽  
pp. 29-35
Author(s):  
V. P. Sirotinkin ◽  
O. V. Baranov ◽  
A. Yu. Fedotov ◽  
S. M. Barinov
Keyword(s):  
Phase Composition ◽  
Calcium Phosphates ◽  
Position Sensitive Detector ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Impurity Phases ◽  
Position Sensitive ◽  
Diffraction Peaks ◽  
Diffraction Patterns

The results of studying the phase composition of advanced calcium phosphates Ca10(PO4)6(OH)2, β-Ca3(PO4)2, α-Ca3(PO4)2, CaHPO4 · 2H2O, Ca8(HPO4)2(PO4)4 · 5H2O using an x-ray diffractometer with a curved position-sensitive detector are presented. Optimal experimental conditions (angular positions of the x-ray tube and detector, size of the slits, exposure time) were determined with allowance for possible formation of the impurity phases during synthesis. The construction features of diffractometers with a position-sensitive detector affecting the profile characteristics of x-ray diffraction peaks are considered. The composition for calibration of the diffractometer (a mixture of sodium acetate and yttrium oxide) was determined. Theoretical x-ray diffraction patterns for corresponding calcium phosphates are constructed on the basis of the literature data. These x-ray diffraction patterns were used to determine the phase composition of the advanced calcium phosphates. The features of advanced calcium phosphates, which should be taken into account during the phase analysis, are indicated. The powder of high-temperature form of tricalcium phosphate strongly adsorbs water from the environment. A strong texture is observed on the x-ray diffraction spectra of dicalcium phosphate dihydrate. A rather specific x-ray diffraction pattern of octacalcium phosphate pentahydrate revealed the only one strong peak at small angles. In all cases, significant deviations are observed for the recorded angular positions and relative intensity of the diffraction peaks. The results of the study of experimentally obtained mixtures of calcium phosphate are presented. It is shown that the graphic comparison of experimental x-ray diffraction spectra and pre-recorded spectra of the reference calcium phosphates and possible impurity phases is the most effective method. In this case, there is no need for calibration. When using this method, the total time for analysis of one sample is no more than 10 min.

Second Order Stresses Distribution in Textured Copper

2006 ◽  
Vol 524-525 ◽  
pp. 859-864
Author(s):  
Neila Hfaiedh ◽  
Manuel François ◽  
Khemais Saanouni
Keyword(s):  
Peak Position ◽  
Second Order ◽  
Polycrystalline Materials ◽  
Internal Stresses ◽  
Plastic Strains ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Position Sensitive ◽  
Specific Correction

Internal stresses are an important factor in understanding the work hardening behaviour of polycrystalline materials. The goal of the present paper is to study the development of second order stresses in textured copper sheets at large plastic strains, up to fracture by X-ray diffraction. Second order stresses manifest themselves as peak displacements and width changes as azimuth and tilt angles are varied. As the acquisition is performed with a position sensitive detector, a specific correction of intensities is required in order to take into account texture influence on peak shape and consequently on peak position and width.

Absorption corrections and digital filtering of X-ray diffraction profiles recorded with a position-sensitive detector

1985 ◽  
Vol 18 (6) ◽  
pp. 487-492 ◽  
Author(s):  
A. Burian ◽  
P. Lecante ◽  
A. Mosset ◽  
J. Galy ◽  
J. Van Dun ◽  
...  
Keyword(s):  
Digital Filtering ◽  
Position Sensitive Detector ◽  
Correction Function ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Absorption Correction ◽  
Pertinent Information ◽  
Position Sensitive ◽  
Transmission And Reflection

Expressions for the absorption correction function are obtained in the form of integral equations for the case of a flat-plate sample and a position-sensitive detector. It is shown that the absorption correction used for both transmission and reflection geometries with a conventional diffractometer may be applied to a diffractometer equipped with a linear position-sensitive detector. The application of a Savitzky–Golay-type digital filter considerably facilitates the analysis of the data without losing pertinent information.

Synthesis and Characterization of A Metastable (SiC)aN4 Phase

1994 ◽  
Vol 354 ◽  
Author(s):  
C. Uslu ◽  
B. Park ◽  
D. B. Poker
Keyword(s):  
Cubic Phase ◽  
High Dose ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
Cross Sectional ◽  
X Ray ◽  
Transmission Electron ◽  
Position Sensitive ◽  
New Phase

AbstractA metastable C-Si-N compound has been synthesized by high dose N+ implantation into polycrystalline /8-SiC (cubic phase). The thin films formed upon 100 keV implantations were characterized with respect to various ion doses and target temperatures. X-ray diffraction with a position-sensitive detector and cross-sectional transmission electron microscopy revealed that the as-implanted surfaces contained ∼0.15 jttm thick continuously-buried amorphous layers. Rutherford backscattering spectroscopy showed that the peak concentration of nitrogen saturated up to approximately 54 at. % with increasing doses, suggesting a new phase formation.

Automated Quantitative Multiphase Analysis Using a Focusing Transmission Diffractometer in Conjunction With a Curved Position Sensitive Detector

1987 ◽  
Vol 31 ◽  
pp. 325-330
Author(s):  
B. A. Foster ◽  
E. R. Wolfel
Keyword(s):  
Scintillation Counter ◽  
Position Sensitive Detector ◽  
Transmission Factor ◽  
Sensitive Detector ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sample Matrix ◽  
Position Sensitive ◽  
Transmission Measurements ◽  
Automatic Focusing

The method for quantitative X-ray diffraction analysis of multiphase mixtures presented here is based on transmission measurements of thin samples. The integral of all reflections of interest are measured with a position sensitive detector at one time while the transmission factor of the sample is measured simultaneously with a scintillation counter. The method has the advantages that only a few (1-5) mg of substance are required, absorption effects due to sample matrix are measured directly and the method is automated. The measurements are made with the STOE/ Nicolet Automatic Focusing X-ray Diffraction system in conjunction with the STOE/Nicolet Curved Position Sensitive Detector.

Non-Destructive X-Ray Diffraction with 30-Micron Spatial Resolution: Some Examples

1992 ◽  
Vol 267 ◽  
Author(s):  
M. Inaba ◽  
J. Miyata ◽  
R. Sugisita
Keyword(s):  
Powder Diffraction ◽  
Cross Sections ◽  
Small Samples ◽  
Wide Angle ◽  
X Ray Diffraction ◽  
X Ray ◽  
Multichannel Analyser ◽  
Position Sensitive ◽  
Non Destructive ◽  
Measurement Period

ABSTRACTWe have been measuring x-ray diffraction spectra of small samples of layers in cross-sections using a Micro X-ray diffractometer (PSPC/MDG) system since 1988. In measuring with xray diffractometry, the position sensitive proportional counter (PSPC) covers 150 degrees of x-ray diffraction, continuously. The data are accumulated by the multichannel analyser (MCA) and monitored on a CRT during the measurement period. Mounted samples can rotate around three axes. The XRD spectra are very like those from a wide angle goniometer used in powder diffraction. Normally the spatial limits are around 30 microns in diameter, as we have found experimentallly in our samples. We feel this system is very feasible for art and archaeological studies. Some case studies are presented.

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