Stability of fcc phase FeH to 137 GPa

2020 ◽  
Vol 105 (6) ◽  
pp. 917-921
Author(s):  
Chie Kato ◽  
Koichiro Umemoto ◽  
Kenji Ohta ◽  
Shoh Tagawa ◽  
Kei Hirose ◽  
...  
Keyword(s):  
High Pressure ◽  
Ab Initio ◽  
Magnetic Transition ◽  
Stability Field ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
High Pressure And Temperature ◽  
Face Centered ◽  
Fcc Phase ◽  
Fcc Structure

Abstract We examined the crystal structure of FeHX (X~1) (FeH hereafter) at high pressure and temperature by X-ray diffraction up to 137 GPa. Results show that FeH adopts a face-centered cubic (fcc) structure at pressures of 43 to 137 GPa and temperatures of ~1000 to 2000 K. Our study revises a phase diagram of stoichiometric FeH in which fcc has a wider-than-expected stability field at high pressure and temperature. Based on our findings, the FeH end-member of the Fe-FeH system is expected to be stable in the fcc structure at the P-T conditions of the Earth's core, rather than in the double-hexagonal close packed (dhcp) structure as previously reported. We compared the experimentally determined unit-cell volumes of FeH with those from ab initio calculations. Additionally, we observed a change in compressibility at ~60 GPa, which could be attributed to a magnetic transition—an interpretation supported by our ab initio computations.

Ozone-Based Atomic Layer Deposition of HfO2 and HfxSi1-xO2 and Film Characterization

2004 ◽  
Vol 811 ◽  
Author(s):  
Yoshihide Senzaki ◽  
Seung Park ◽  
Douglas Tweet ◽  
John F. Conley ◽  
Yoshi Ono
Keyword(s):  
Atomic Layer ◽  
Optical Measurements ◽  
Face Centered Cubic ◽  
Hafnium Silicate ◽  
X Ray ◽  
Layer Deposition ◽  
Face Centered ◽  
Fcc Phase ◽  
20 Nm ◽  
Fcc Structure

Abstract:New ALD processes for hafnium silicate films have been developed at Aviza Technology by co-injection of tetrakis(ethylmethylamino)hafnium and tetrakis(ethylmethylamino)silicon precursors. Alternating pulses of the Hf/Si precursor vapor mixture and ozone allow process temperatures below 400°C to grow HfxSi1-xO2 films. Film characterization, including film density, crystallinity, and thermal anneal effect, was performed on five 20 nm thick HfxSi1-xO2 films where x = 0.2, 0.4, 0.6, 0.8, 1.0. X-ray measurements revealed the film densities and thicknesses for the as-deposited and 1000°C annealed samples. The densification with anneals seen in the optical measurements were confirmed. The as-deposited amorphous HfO2 and Hf0.8Si0.2O2 were crystallized after a 600°C anneal. The HfO2 formed the well known monoclinic phase while the silicate formed a face-centered-cubic (fcc) structure. This fcc phase has only recently been mentioned in the literature [1].

Grain Growth and Mechanical Properties of Nanograined Bulk Fe-25Ni Alloy

2005 ◽  
Vol 475-479 ◽  
pp. 3459-3462
Author(s):  
Hong Bin Wang ◽  
Xiao Yu Wang ◽  
J.H. Zhang ◽  
T.Y. Hsu
Keyword(s):  
Mechanical Properties ◽  
Grain Growth ◽  
Coarse Grained ◽  
Growth Exponent ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Ni Alloy ◽  
Face Centered ◽  
Fcc Phase

The grain growth and mechanical properties of nanograined bulk Fe-25at%Ni alloy prepared by an inert gas condensation and in-situ warm consolidation technique were investigated. About 43% high temperature face-centered-cubic (FCC) phase and 57% low temperature body-centered-cubic (BCC) phase were observed in the sample at room temperature, which was significantly different from that of the corresponding conventional coarse-grained alloy. The in-situ X-ray diffraction results show that the start and the finish temperature of BCC to FCC phase transformation are 450°C and 600°C, respectively. The isothermal grain growth exponent n from t k D D n n ¢ = − 1 0 1 for nanograined single FCC phase Fe-25at%Ni alloy is 0.38 at 750 °C . The mechanical properties changing with the grain size were studied by means of microindentation test.

Measured and calculated thermoelastic properties of supersaturated fcc Ni(Al) and Ni(Zr) solid solutions

1998 ◽  
Vol 13 (6) ◽  
pp. 1717-1723 ◽  
Author(s):  
J. Bøttiger ◽  
N. Karpe ◽  
J. P. Krog ◽  
A. V. Ruban
Keyword(s):  
Solid Solutions ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Lattice Constants ◽  
Thermal Expansion Coefficients ◽  
Debye Temperatures ◽  
Expansion Coefficients ◽  
Face Centered ◽  
Fcc Phase ◽  
Film Form

Metastable face-centered cubic (fcc) solid solutions of Ni1–xAlx and Ni1–xZrx have been prepared in thin-film form using dc planar magnetron sputtering in a UHV system. In both these alloy systems, extended solubilities in the fcc phase and a pronounced (111) texture are observed after sputter deposition. An amorphous phase is found to form in Ni1–xAlx for x ≥ 0.30 and in Ni1–xZrx for x ≥ 0.05. Lattice constants, thermal expansion coefficients, and Debye temperatures were derived from x-ray diffraction measurements. These parameters were also calculated by using ab initio methods in the framework of the local-spin density and coherent potential approximations for the electronic subsystem and the Debye–Grüneisen model for the vibrational properties of the nuclei subsystem. Experiment and theory are compared and discussed.

In situ high-temperature X-ray diffraction characterization of silver sulfide, Ag2S

2011 ◽  
Vol 26 (2) ◽  
pp. 114-118 ◽  
Author(s):  
Thomas Blanton ◽  
Scott Misture ◽  
Narasimharao Dontula ◽  
Swavek Zdzieszynski
Keyword(s):  
High Temperature ◽  
Structure Refinement ◽  
Silver Sulfide ◽  
Rietveld Analysis ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
X Ray ◽  
Face Centered ◽  
Fcc Phase

Silver sulfide, Ag2S, is most commonly known as the tarnish that forms on silver surfaces due to the exposure of silver to hydrogen sulfide. The mineral acanthite is a monoclinic crystalline form of Ag2S that is stable to 176°C. Upon heating above 176°C, there is a phase conversion to a body-centered cubic (bcc) form referred to as argentite. Further heating above 586°C results in conversion of the bcc phase to a face-centered cubic (fcc) phase polymorph. Both high-temperature cubic phases are solid-state silver ion conductors. In situ high-temperature X-ray diffraction was used to better understand the polymorphs of Ag2S on heating. The existing powder diffraction file (PDF) entries for the high-temperature fcc polymorph are of questionable reliability, prompting a full Rietveld structure refinement of the bcc and fcc polymorphs. Rietveld analysis was useful to show that the silver atoms are largely disordered and can only be described by unreasonably large isotropic displacement parameters or split site models.

Fabrication of Gold Nanocubes by the Electrochemical Method

2008 ◽  
Vol 55-57 ◽  
pp. 661-664 ◽  
Author(s):  
Chien Jung Huang ◽  
Pin Hsiang Chiu ◽  
Yeong Her Wang ◽  
Kan Lin Chen
Keyword(s):  
Electrochemical Method ◽  
Cetyltrimethylammonium Bromide ◽  
Xrd Analysis ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Uniform Size ◽  
Surfactant Micelle ◽  
X Ray ◽  
Face Centered ◽  
Fcc Structure

This paper demonstrates synthesis of gold nanocubes with uniform size about 30 nm by a simple electrochemical method. The surfactant cetyltrimethylammonium bromide (CTAB) and tetradodecylammonium bromide (TTAB) were used as the stabilizer and micelle template to control the size and shape of gold nanocubes. In this study, acetone solvent was injected to the electrolyte solution with surfactant, changing the surfactant micelle-template, leading to the formation of gold nanocubes. The gold nanocubes have a surface plasmon resonance (SPR) band at a wavelength of about 530 nm. The gold nanodumbbells have been determined to be single-crystalline with a face-centered cubic (fcc) structure by X-ray diffraction (XRD) analysis.

Synthesis of Well-Dispersed Copper Nanoparticles by L-Ascorbic Acid in Diethyleneglycol

2012 ◽  
Vol 549 ◽  
pp. 378-381 ◽  
Author(s):  
Jun Cheng Zhou ◽  
Wei He ◽  
Yao Tang ◽  
Yong Suan Hu
Keyword(s):  
Electron Microscopy ◽  
Ascorbic Acid ◽  
Copper Nanoparticles ◽  
Metallic Copper ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Copper Particles ◽  
Transmission Electron ◽  
Face Centered ◽  
Fcc Structure

Metallic copper nanoparticles were synthesized in the presence of poly(N-vinylpyrrolidone) (PVP) as the capping agent and L-ascorbic acid as the reducing agent in diethyleneglycol (DEG) solvent. The obtained copper nanoparticles were characterized by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The EDS and XRD results showed that the resultant particles were confirmed to be crystalline Cu with a face-centered cubic (fcc) structure. It was also observed that the diameter of obtained copper particles ranging from 80 to 120nm via SEM and TEM.

Synthesis and Characterization of Silver Nanowires

2013 ◽  
Vol 678 ◽  
pp. 212-216
Author(s):  
Subbaiyan Sugapriya ◽  
Rangarajalu Sriram ◽  
Sriram Lakshmi
Keyword(s):  
Silver Nanowires ◽  
Synthesis And Characterization ◽  
Face Centered Cubic ◽  
Capping Agent ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Face Centered ◽  
Fcc Structure

ABSTRACT Silver nanowires have been synthesized by polyol process with ethylene glycol as solvent and PVP as capping agent. The silver nanowires have been characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), and Transmission electron microscope (TEM) techniques. The prepared silver nanowires were found to exhibit face-centered cubic (fcc) structure. The diameter of the prepared silver nanowires have been found to lie in the range of 60 - 80 nm and the length of the wires have been observed to be in the range of 10-20 µm. The I-V characteristics have been carried out to study the conducting behavior of the prepared silver nanowires.

Platinum Immobilization on Iron Oxide Nanoparticles Surface under Sonication

2011 ◽  
Vol 183-185 ◽  
pp. 1989-1994
Author(s):  
Quan Guo He ◽  
Zhao Hui Wu ◽  
Rong Hu
Keyword(s):  
Iron Oxide ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Environment Friendly ◽  
X Ray ◽  
Composite Microspheres ◽  
Selected Area Electron Diffraction ◽  
Transmission Electron ◽  
Face Centered ◽  
Fcc Structure

A facile and environment-friendly sonochemical route to fabricate well-defined Fe3O4/Pt and γ-Fe2O3/Pt composite microspheres under mild conditions has been reported. The structure and morphology of the synthetic spherical-shaped Fe3O4/Pt and γ-Fe2O3/Pt products were characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM) with selected area electron diffraction (SAED). The results revealed that the composites were spherical with diameter in the range of 50–80 nm and had an ordered face-centered cubic (fcc) structure of platinum. These nanocomposites with platinum-coated iron oxide can be applied in a variety of areas, including medicine, photonics, new functional device assemblies and catalysis especially for fabricating some magnetic-responsive catalyst.

Metallurgical Aspects of High-palladium Alloys

1988 ◽  
Vol 67 (10) ◽  
pp. 1307-1311 ◽  
Author(s):  
P.R. Mezger ◽  
A.L.H. Stols ◽  
M.M.A. Vrijhoef ◽  
E.H. Greener
Keyword(s):  
Face Centered Cubic ◽  
Body Centered Cubic ◽  
Palladium Alloys ◽  
Secondary Phases ◽  
X Ray Diffraction ◽  
X Ray ◽  
Simple Cubic ◽  
Face Centered ◽  
Fcc Phase ◽  
Multi Phase

Nine commercial high-Pd alloys were investigated. Microstructure and phase composition were screened by x-ray diffraction, light microscopy, and an electron microprobe. After being etched, some high-Pd alloys revealed dendritic structures. The others showed a more homogeneous structure with distinct grain boundaries. Etching was necessary to reveal distinct structures, though the overall etching effect turned out to be limited. On unetched specimens, only a slight chemical heterogeneity could be determined. Except for one alloy, the systems turned out to have complex multi-phase structures. The main face-centered-cubic (fcc) phase was Pd-based. As secondary phases, body-centered-cubic (bcc) and/or simple cubic ones were detected. The latter phases were similar to a Cu3Ga and PdGa intermetallic compound, respectively. Face-centered-tetragonal (fct) structures reported by other investigators were not found.

scholarly journals High pressure-induced distortion in face-centered cubic phase of thallium

2016 ◽  
Vol 113 (40) ◽  
pp. 11143-11147 ◽  
Author(s):  
Komsilp Kotmool ◽  
Bing Li ◽  
Sudip Chakraborty ◽  
Thiti Bovornratanaraks ◽  
Wei Luo ◽  
...  
Keyword(s):  
High Pressure ◽  
Density Functional ◽  
Cubic Phase ◽  
Face Centered Cubic ◽  
X Ray Diffraction ◽  
Functional Theory ◽  
High Pressure Phase Transition ◽  
The Density Functional Theory ◽  
Face Centered ◽  
Mixing States

The complex and unusual high-pressure phase transition of III-A (i.e. Al, Ga, and In) metals have been investigated in the last several decades because of their interesting periodic table position between the elements having metallic and covalent bonding. Our present first principles-based electronic structure calculations and experimental investigation have revealed the unusual distortion in face-centered cubic (f.c.c.) phase of the heavy element thallium (Tl) induced by the high pressure. We have predicted body-centered tetragonal (b.c.t) phase at 83 GPa using an evolutionary algorithm coupled with ab initio calculations, and this prediction has been confirmed with a slightly distorted parameter (2 × a − c)/c lowered by 1% using an angle-dispersive X-ray diffraction technique. The density functional theory (DFT)-based calculations suggest that s–p mixing states and the valence-core overlapping of 6s and 5d states play the most important roles for the phase transitions along the pathway h.c.p→f.c.c.→b.c.t.

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