scholarly journals KSm(MoO4)2, an incommensurately modulated and partially disordered scheelite-like structure

2008 ◽  
Vol 64 (2) ◽  
pp. 160-171 ◽  
Author(s):  
Alla Arakcheeva ◽  
Philip Pattison ◽  
Gervais Chapuis ◽  
Marta Rossell ◽  
Andrey Filaretov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Synchrotron Radiation ◽  
Powder Diffraction ◽  
Rietveld Method ◽  
Cation Ordering ◽  
Powder Diffraction Data ◽  
Line Broadening ◽  
Transmission Electron ◽  
Wave Distribution

The incommensurately modulated scheelite-like KSm(MoO4)2 structure has been refined in the monoclinic superspace group I2/b(αβ0)00 by the Rietveld method on the basis of synchrotron radiation powder diffraction data. The systematic broadening of satellite reflections has been accounted for by applying anisotropic microstrain line-broadening. The microstructure has been studied by transmission electron microscopy (TEM). The partial disorder of the K and Sm cations in the A position is best approximated by a combination of harmonic and complex crenel functions with (0.952Sm + 0.048K) and (0.952K + 0.048Sm) atomic domains. This combination yields a compositional wave distribution from {KMoO4} to {SmMoO4} observed in the ab structure projection along q. The specific features of KSm(MoO4)2 and degree of the A-cation ordering are discussed in comparison with the previously reported structure of KNd(MoO4)2.

scholarly journals Combining powder diffraction with TEM for solving modulated structures

2014 ◽  
Vol 70 (a1) ◽  
pp. C135-C135
Author(s):  
Artem Abakumov
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Powder Diffraction ◽  
Diffraction Data ◽  
Real Space ◽  
Space Structure ◽  
Electron Diffraction Data ◽  
Powder Diffraction Data ◽  
Transmission Electron ◽  
Modulated Structures

In many materials competing interactions of different nature may give rise to incommensurate modulations causing extreme structure complexity. Ab initio solution of the modulated structures even with using high quality synchrotron X-ray and/or neutron powder diffraction data appears to be a very challenging problem due to weakness of the satellite reflections, ambiguity in the determination of the modulation vector(s) and superspace symmetry and difficulties in building the initial model for further Rietveld refinement. These problems can be resolved or, at least, mitigated if the diffraction, imaging and spectroscopic advanced transmission electron microscopy techniques are combined with the analysis of powder diffraction data. Complete reconstruction of the reciprocal space, structure solution using quasi-kinematical electron diffraction data, mapping projected scattering density in the unit cell, visualization of the light atoms, displacive and occupational ordering, mapping chemical composition and coordination number can be utilized to reveal the nature of incommensurate modulations and construct the reliable model for the refinement from powder diffraction data. The benefit of the strategy of combining the powder diffraction data with the reciprocal and real space information obtained using aberration-corrected scanning transmission electron microscopy will be illustrated on the examples of the transition metal oxides: Li3xNd2/3-xTiO3 perovskites with frustrated incommensurately modulated octahedral tilting pattern [1]; perovskites (Bi,Pb)1-xFe1+xO3-y, modulated by crystallographic shear planes [2]; CaGd2(1-x)Eu2x(MoO4)4(1-y)(WO4)4y scheelites with incommensurately modulated ordering of cation vacancies [3].

scholarly journals Synchrotron Radiation Spectroscopy and Transmission Electron Microscopy Techniques to Evaluate TiO2 NPs Incorporation, Speciation, and Impact on Root Cells Ultrastructure of Pisum sativum L. Plants

Nanomaterials ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 921
Author(s):  
Simonetta Muccifora ◽  
Hiram Castillo-Michel ◽  
Francesco Barbieri ◽  
Lorenza Bellani ◽  
Monica Ruffini Castiglione ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Synchrotron Radiation ◽  
Pisum Sativum ◽  
Emission Spectrometry ◽  
Root Cells ◽  
Tio2 Nps ◽  
X Ray ◽  
Pisum Sativum L ◽  
Transmission Electron

Biosolids (Bs) for use in agriculture are an important way for introducing and transferring TiO2 nanoparticles (NPs) to plants and food chain. Roots of Pisum sativum L. plants grown in Bs-amended soils spiked with TiO2 800 mg/kg as rutile NPs, anatase NPs, mixture of both NPs and submicron particles (SMPs) were investigated by Transmission Electron Microscopy (TEM), synchrotron radiation based micro X-ray Fluorescence and micro X-ray Absorption Near-Edge Structure (µXRF/µXANES) and Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES). TEM analysis showed damages in cells ultrastructure of all treated samples, although a more evident effect was observed with single anatase or rutile NPs treatments. Micro-XRF and TEM evidenced the presence of nano and SMPs mainly in the cortex cells near the rhizodermis. Micro-XRF/micro-XANES analysis revealed anatase, rutile, and ilmenite as the main TiO2 polymorphs in the original soil and Bs, and the preferential anatase uptake by the roots. For all treatments Ti concentration in the roots increased by 38–56%, however plants translocation factor (TF) increased mostly with NPs treatment (261–315%) and less with SMPs (about 85%), with respect to control. In addition, all samples showed a limited transfer of TiO2 to the shoots (very low TF value). These findings evidenced a potential toxicity of TiO2 NPs present in Bs and accumulating in soil, suggesting the necessity of appropriate regulations for the occurrence of NPs in Bs used in agriculture.

Synthesis and Characterizations of Nanocubes, Monodispersed Nanocrystals and Nanospheres of Au

2007 ◽  
Vol 353-358 ◽  
pp. 2163-2166
Author(s):  
Ming Yang ◽  
Guo Qing Zhou ◽  
Jiang Guo Zhao ◽  
Zhan Jun Li
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Powder Diffraction ◽  
Visible Absorption ◽  
X Ray ◽  
Transmission Electron ◽  
Uv Visible ◽  
Scherrer Formula ◽  
Visible Absorption Spectroscopy

Nanocubes, monodispersed nanocrystals and nanospheres of Au have been prepared by a simple reaction between HAuCl4·4H2O, NaOH and NH2OH·HCl in the presence of gelatin. The role of gelatin and the affection of pH in producing the nanoparticles of Au were discussed. The products were characterized by X-ray powder diffraction, transmission electron microscopy, and UV-visible absorption spectroscopy. The sizes of the monodispersed nanocrystals of Au were estimated by Debye-Scherrer formula according to XRD spectrum.

scholarly journals Crystallite Size Evaluation of ZnO Nanoparticles via Transmission Electron Microscopy and X-ray Powder Diffraction

2016 ◽  
Vol 22 (S3) ◽  
pp. 1610-1611
Author(s):  
Jonathan E. Cowen ◽  
Ashley E. Harris ◽  
Cecelia C. Pena ◽  
Stephen C. Bryant ◽  
Allison J. Christy ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Crystallite Size ◽  
Powder Diffraction ◽  
Zno Nanoparticles ◽  
X Ray ◽  
Transmission Electron ◽  
Size Evaluation

Ultrasonic Synthesis of Ag2Se Nanocrystal in Perrhenate Solution

2014 ◽  
Vol 919-921 ◽  
pp. 2109-2111 ◽  
Author(s):  
Wei Jun Shan ◽  
Qiang Yan ◽  
Du Li ◽  
Da Wei Fang ◽  
Shu Liang Zang
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Powder Diffraction ◽  
Ambient Pressure ◽  
Ion Source ◽  
Metal Chalcogenide ◽  
X Ray ◽  
Ultrasonic Synthesis ◽  
Transmission Electron ◽  
Se Nanoparticles

Ag2Se nanocrystal was successfully prepared by ultrasonic synthesis in water and ethanol systems at an ambient pressure. The powder of selenium was used as the selenium ion source. The size of the nanocrystals is in the scope of 10-20nm. The products were characterized by some means including X-ray Powder Diffraction (XRD) and Transmission Electron Microscopy (TEM) which was used to study the thermostability of the product. The result of the experiments indicated that the concentration of the reactant, the pH of the solution, the react temperature and the surfactant had some important influence on the formation and the size of the Ag2Se nanoparticles. The method we reported here is proved to be a new and an easy way to prepare the nanocrystals of metal chalcogenide.

Multidimensional Disorder in Zeolite IM-18 Revealed by Combining Transmission Electron Microscopy and X-ray Powder Diffraction Analyses

2018 ◽  
Vol 18 (4) ◽  
pp. 2441-2451 ◽  
Author(s):  
Magdalena O. Cichocka ◽  
Yannick Lorgouilloux ◽  
Stef Smeets ◽  
Jie Su ◽  
Wei Wan ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Powder Diffraction ◽  
X Ray ◽  
Transmission Electron
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