EXAFS investigation of the role of Cu on the chemical order and lattice distortion in L10Fe–Pt–Cu thin films

2014 ◽  
Vol 47 (5) ◽  
pp. 1722-1728 ◽  
Author(s):  
S. Laureti ◽  
C. Brombacher ◽  
D. Makarov ◽  
M. Albrecht ◽  
D. Peddis ◽  
...  
Keyword(s):  
Lattice Distortion ◽  
Structural Evolution ◽  
Local Environment ◽  
Linear Dichroism ◽  
Ternary Alloys ◽  
Chemical Order ◽  
Cu Content ◽  
Exafs Study

This work presents an extended X-ray absorption fine structure (EXAFS) characterization of ternary Fe–Pt–Cu alloys with different Cu content. The EXAFS measurements have been carried out at the CuKα and PtLIIIedges in order to describe the local environment around these elements in the Fe–Pt–Cu samples and to compare the structural evolution as a function of the Cu content. The EXAFS study, based on a substitutional model where the Cu atoms occupy Fe or Pt sites in the tetragonal structure, has been performed by using linear dichroism to enhance the sensitivity to differently oriented bonds and to gain a detailed description of the atomic environment. The study allowed the effects on the chemical order and lattice distortion induced by the Cu atoms to be distinguished experimentally. The determined positions of the Cu atoms in the chemically L10-ordered face-centred tetragonal lattice were correlated with the magnetic properties of Fe–Pt–Cu ternary alloys. In particular, the main effect of Cu atoms in the alloy is a linear reduction of thec/aratio, while the nonmonotonic behaviour of the chemical order is consistent with the variation of the magnetocrystalline anisotropy.

Structural role of copper in the minerals of the pearceite-polybasite group: the case of the new minerals cupropearceite and cupropolybasite

2007 ◽  
Vol 71 (06) ◽  
pp. 641-650 ◽  
Author(s):  
L. Bindi ◽  
M. Evain ◽  
P. G. Spry ◽  
K. T. Tait ◽  
S. Menchetti
Keyword(s):  
Chemical Characterization ◽  
Sample Space ◽  
The Other ◽  
Crystal Chemical ◽  
Structural Position ◽  
Space Group ◽  
Cu Content ◽  
Own Name

Abstract The pearceite-polybasite group of minerals, general formula [M6T2S7][Ag9CuS4] with M = Ag, Cu; and T = As, Sb, show a crystal structure which can be described as the succession, along the c axis, of two pseudo-layer modules: a [M6T2S7]2– A module layer and a [Ag9CuS4]2+ B module layer. Copper is present in one structural position of the B module layer and replaces Ag in the only fully occupied M position of the A module layer. When the Cu content is >4.00 a.p.f.u., the structural position of the A module layer becomes Cu-dominant and, consequently, the mineral deserves its own name. In this paper we report the crystal-chemical characterization of two Cu-rich members exhibiting the 111 unitcell type (corresponding to the Tac polytype). One sample (space group (P )m1, a 7.3218(8), c 11.8877(13) Å, V 551.90(10) Å3, Z = 1) having As >Sb and with the structural position of the A module layer dominated by Cu, has been named cupropearceite and the other sample (space group (P3̄)m1, a 7.3277(3), c 11.7752(6) Å, V 547.56(8) Å3, Z = 1) having Sb >As has been named cupropolybasite. Both the new minerals and mineral names have been approved by the IMA-CNMNC.

scholarly journals Peculiar Structural Effects in Pure and Doped Functional Single Crystals of Complex Compositions

Molecules ◽  
2020 ◽  
Vol 25 (10) ◽  
pp. 2451
Author(s):  
Galina Kuz’micheva ◽  
Irina Kaurova
Keyword(s):  
Single Crystal ◽  
Single Crystals ◽  
Functional Materials ◽  
Local Environment ◽  
Structural Effects ◽  
Local Structures ◽  
Annealing Conditions ◽  
Activator Ions

Results of a detailed structural characterization of nominally pure and doped single crystals of scheelite, eulytin, and perovskite families obtained by melt methods were considered and analyzed. The influence of growth and post-growth annealing conditions on actual compositions of crystals is shown. The reasons for the coloration of the crystals are explained. A change in crystal symmetry due to crystal–chemical and growth reasons is considered. The use of structural analysis and X-ray absorption spectroscopy is substantiated to reveal the role of activator ions in the formation of statistical and local structures, respectively. A relationship between the distribution of activator ions over crystallographic sites and photoluminescent parameters of materials is established, which allows selecting optimal systems for the application. The combined results of studying single-crystal compounds of other classes (huntite, sillenite, whitlockite, garnet, tetragonal bronzes) allow formulating and summarizing structural effects that appeared in the systems and caused by various factors and, in many cases, due to the local environment of cations. A principal difference in the structural behavior of solid solutions and doped compounds is shown. The methodology developed for single-crystal samples of complex compositions can be recommended for the systematic structural studies of functional materials of different compositions.

Structural characterization of Ti implanted AlN

1995 ◽  
Vol 10 (12) ◽  
pp. 3136-3142 ◽  
Author(s):  
M. Borowski ◽  
A. Traverse ◽  
J.P. Dallas
Keyword(s):  
Chemical Properties ◽  
Local Environment ◽  
Heat Of Formation ◽  
Implantation Process ◽  
Calculated Distribution ◽  
Final System ◽  
Post Implantation ◽  
Key Parameter

Sintered AlN ceramics were implanted by 1 × 1017 Ti/cm2 at an energy of 70 keV in order to investigate the role of the chemical properties of the implanted species on the phase formed during the implantation process. The implanted ions were found in a depth profile corresponding to the calculated distribution of the vacancies produced during the implantation process instead of the predicted ion profile. Identification of the local environment of Ti and of the resulting phase led us to conclude that Ti is surrounded by N after the collision cascade and forms TiN after post-implantation annealing. The TiN nucleus if formed by substitution of Al by Ti. Therefore, the heat of formation, which is more negative for TiN than for AlN, is found to be a key parameter to predict the final system.

Combinatorial Synthesis and Characterization of CoMnGe Alloys

2001 ◽  
Vol 700 ◽  
Author(s):  
Frank Tsui ◽  
Liang He ◽  
Lei Ma
Keyword(s):  
Structural Evolution ◽  
Magnetic Behavior ◽  
High Energy ◽  
Ternary Alloys ◽  
Si Substrates ◽  
Transport Studies ◽  
Time Scanning ◽  
High Spin Polarization ◽  
Spin Electronic

AbstractTernary alloys of CoMnGe have been synthesized and characterized using combinatorial molecular beam epitaxy techniques. Structural evolution was studied using real-time scanning reflection high-energy electron diffraction, and magnetic properties were probed using magnetooptic Kerr effect imaging and SQUID magnetometry. Growth and properties on several substrate orientations were explored. These alloys exhibit a rich variety of magnetic and magnetooptic behavior, including a robust phase near Co2MnGe with high spin polarization, Tc, and magnetooptic response. The observed magnetic responses show strong correlation with structural transformations, such that structural ordering leads to enhanced magnetism. The observed magnetic behavior and the alloys’ compatibility with Ge and Si substrates make them potential candidates for spin electronic transport studies and applications.

Digital x-ray mapping of nanometer-size supported bimetallic catalysts

1988 ◽  
Vol 46 ◽  
pp. 530-531
Author(s):  
L. T. Germinario
Keyword(s):  
Background Radiation ◽  
Metal Cluster ◽  
Single Element ◽  
Beam Diameter ◽  
X Rays ◽  
X Ray ◽  
Major Interest ◽  
Induced Changes

Understanding the role of metal cluster composition in determining catalytic selectivity and activity is of major interest in heterogeneous catalysis. The electron microscope is well established as a powerful tool for ultrastructural and compositional characterization of support and catalyst. Because the spatial resolution of x-ray microanalysis is defined by the smallest beam diameter into which the required number of electrons can be focused, the dedicated STEM with FEG is the instrument of choice. The main sources of errors in energy dispersive x-ray analysis (EDS) are: (1) beam-induced changes in specimen composition, (2) specimen drift, (3) instrumental factors which produce background radiation, and (4) basic statistical limitations which result in the detection of a finite number of x-ray photons. Digital beam techniques have been described for supported single-element metal clusters with spatial resolutions of about 10 nm. However, the detection of spurious characteristic x-rays away from catalyst particles produced images requiring several image processing steps.

Microstructure and reactivity of small metal particles: The role of Ce additives

1992 ◽  
Vol 50 (1) ◽  
pp. 318-319
Author(s):  
L.D. Schmidt ◽  
K. R. Krause ◽  
J. M. Schwartz ◽  
X. Chu
Keyword(s):  
Atmospheric Pressure ◽  
Noble Metals ◽  
Mixed Oxides ◽  
Catalytic Properties ◽  
Chemical Shifts ◽  
Catalytic Converter ◽  
Structural Evolution ◽  
Single Particles ◽  
Small Metal Particles

The evolution of microstructures of 10- to 100-Å diameter particles of Rh and Pt on SiO2 and Al2O3 following treatment in reducing, oxidizing, and reacting conditions have been characterized by TEM. We are able to transfer particles repeatedly between microscope and a reactor furnace so that the structural evolution of single particles can be examined following treatments in gases at atmospheric pressure. We are especially interested in the role of Ce additives on noble metals such as Pt and Rh. These systems are crucial in the automotive catalytic converter, and rare earths can significantly modify catalytic properties in many reactions. In particular, we are concerned with the oxidation state of Ce and its role in formation of mixed oxides with metals or with the support. For this we employ EELS in TEM, a technique uniquely suited to detect chemical shifts with ∼30Å resolution.

Consideraciones en torno a la reducción solipsista

1970 ◽  
Vol 11 ◽  
Author(s):  
Natalia Carolina Petrillo

ResumenEn el presente trabajo se intentará mostrar que la fenomenología no conduce a una postura solipsista. Para ello, se caracterizará en qué consiste el solipsismo. Luego, se intentará refutar a lo que se ha de llamar “solipsismo metafísico” y “solipsismo gnoseológico”, con el objetivo principal de poner de manifiesto el fundamento de motivación para la salida de la ficción solipsista.Palabras claves:Phenomenology – solipsim – empatía - HusserlAbstractWith the aim of showing that phenomenology does not lead in solipsism, I will first attempt a characterization of it. Then, I will attempt a refutation of the so-called “metaphysical” and “epistemological” solipsisms. Finally, the nature and role of Husserl´s solipsistic fiction is examined, and the grounds that motivate the overcoming of this standpoint are disclosed.key wordsFenomenología – solipsismo - empathy – Husserl

ART STUDIOS – A WAY TO DEVELOPE CHILDREN’S IMAGINATION

2020 ◽  
Vol 11 (1) ◽  
pp. 144-148
Author(s):  
Liuba Zlatkova ◽  
Keyword(s):  
Fairy Tale ◽  
Psychological Effects ◽  
Complete Product ◽  
The Arts ◽  
The Creation ◽  
Role Of Parents

The report describes the steps for creating a musical tale by children in the art studios of „Art Workshop“, Shumen. These studios are led by students volunteers related to the arts from pedagogical department of Shumen University, and are realized in time for optional activities in the school where the child studies. The stages of creating a complete product with the help of different arts are traced – from the birth of the idea; the creation of a fairy tale plot by the children; the characterization of the fairy-tale characters; dressing them in movement, song and speech; creating sets and costumes and creating a finished product to present on stage. The role of parents as a link and a necessary helper for children and leaders is also considered, as well as the positive psychological effects that this cooperation creates.

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