A semiquantitative x‐ray diffraction method to determine mineral composition in stream sediments with similar mineralogy

1989 ◽  
Vol 10 (9) ◽  
pp. 833-844
Author(s):  
Daniel M. Webster
Author(s):  
Roman V. Smelyy ◽  
Ekaterina V. Kaneva ◽  
Anastasiya V. Oshchepkova ◽  
Valerii A. Bychinskii ◽  
Tat’yana S. Aisueva ◽  
...  

The paper reports comparison of three approaches to define the contents of minerals and mineral groups in the carbonate-silicate lake bottom sediments. The two approaches are based on the method of X-ray powder diffraction. The first one treats with the Rietveld Method in the software DIFFRAC Plus diffractometer D8 Advance (PDF-2 database). The second one uses the method of reference intensities (corundum ratios) and optimization of the model powder patterns from the X-ray phase standards of PDF-2 database and equations of the element balance with regularization of the least square functional. The third approach of physic-chemical modeling selects probable single mineral and multi-component phases through modelling the sold solutions, and it uses the data on the element composition obtained by XRF technique, as well as the data of X-ray diffraction on the qualitative mineral composition. Thirty samples of bottom sediment cores taken in the Zun-Torey Lake in East Siberia were analyzed by the three approaches described herein. The contents of mineral groups (feldspars, quartz, clay minerals and carbonates) varied within the range 10-40 mass %. The discrepancies between obtained results show the standard deviation ranging from 2 to 9 mass %. A relative standard deviation commonly provides the value below 30 %, so such determinations could be considered quantitative ones. With regard to the acquired data, it is hard to prefer this or that approach. Available data was employed to assess the error of X-ray phase powder analysis in measuring the abundance of mineral groups in the carbonate-silicate sedimentary rocks in the absence of reference materials to compare with certified mineral composition


2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Durga Sankar Vavilapalli ◽  
Ambrose A. Melvin ◽  
F. Bellarmine ◽  
Ramanjaneyulu Mannam ◽  
Srihari Velaga ◽  
...  

AbstractIdeal sillenite type Bi12FeO20 (BFO) micron sized single crystals have been successfully grown via inexpensive hydrothermal method. The refined single crystal X-ray diffraction data reveals cubic Bi12FeO20 structure with single crystal parameters. Occurrence of rare Fe4+ state is identified via X-ray photoelectron spectroscopy (XPS) and X-ray absorption spectroscopy (XAS). The lattice parameter (a) and corresponding molar volume (Vm) of Bi12FeO20 have been measured in the temperature range of 30–700 °C by the X-ray diffraction method. The thermal expansion coefficient (α) 3.93 × 10–5 K−1 was calculated from the measured values of the parameters. Electronic structure and density of states are investigated by first principle calculations. Photoelectrochemical measurements on single crystals with bandgap of 2 eV reveal significant photo response. The photoactivity of as grown crystals were further investigated by degrading organic effluents such as Methylene blue (MB) and Congo red (CR) under natural sunlight. BFO showed photodegradation efficiency about 74.23% and 32.10% for degrading MB and CR respectively. Interesting morphology and microstructure of pointed spearhead like BFO crystals provide a new insight in designing and synthesizing multifunctional single crystals.


Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 753
Author(s):  
Dmitriy Shlimas ◽  
Artem L. Kozlovskiy ◽  
Maxim Zdorovets

The interest in lithium-containing ceramics is due to their huge potential as blanket materials for thermonuclear reactors for the accumulation of tritium. However, an important factor in their use is the preservation of the stability of their strength and structural properties when under the influence of external factors that determine the time frame of their operation. This paper presents the results of a study that investigated the influence of the LiTiO2 phase on the increasing resistance to degradation and corrosion of Li2TiO3 ceramic when exposed to aggressive acidic media. Using the X-ray diffraction method, it was found that an increase in the concentration of LiClO4·3H2O during synthesis leads to the formation of a cubic LiTiO2 phase in the structure as a result of thermal sintering of the samples. During corrosion tests, it was found that the presence of the LiTiO2 phase leads to a decrease in the degradation rate in acidic media by 20–70%, depending on the concentration of the phase. At the same time, and in contrast to the samples of Li2TiO3 ceramics, for which the mechanisms of degradation during a long stay in aggressive media are accompanied by large mass losses, for the samples containing the LiTiO2 phase, the main degradation mechanism is pitting corrosion with the formation of pitting inclusions.


1990 ◽  
Vol 7 (7) ◽  
pp. 308-311
Author(s):  
Li Chaorong ◽  
Mai Zhenhong ◽  
Cui Shufan ◽  
Zhou Junming ◽  
Yutian Wang

1951 ◽  
Vol 22 (5) ◽  
pp. 665-672 ◽  
Author(s):  
Alfred J. Reis ◽  
Jerome J. Slade ◽  
Sigmund Weissmann

2014 ◽  
Vol 215 ◽  
pp. 470-473 ◽  
Author(s):  
Tamara V. Drokina ◽  
German A. Petrakovskii ◽  
Dmitrii A. Velikanov ◽  
Maksim S. Molokeev

In this paper we are reported about a peculiarity of the crystal structure and the magnetic state of TmFeTi2O7. The compound TmFeTi2O7 has been synthesizedusing the solid-phase reaction method. Using X-ray diffraction method the disorder in the distribution of the iron ions over five nonequivalent crystal sites was observed, also the populations of the iron atoms positions were determined. We show that below Tf = 6 K the magnetization of TmFeTi2O7 depends on the magnetic history of the sample. There are indications for spin glass state. This results allow us to assume the state of spin glass is realized below freezing temperature Tf = 6 K in TmFeTi2O7.


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