Studies on the reaction between strontium carbonate and iron(III) oxide

1971 ◽  
Vol 24 (2) ◽  
pp. 237 ◽  
Author(s):  
J Beretka ◽  
T Brown
Keyword(s):  
Carbon Dioxide ◽  
Low Temperatures ◽  
Intermediate Phase ◽  
Strontium Carbonate ◽  
Direct Reaction ◽  
X Ray Diffraction ◽  
X Ray

The reaction between strontium carbonate and iron(III) oxide has been studied in a system open to the atmosphere and in a vacuum. The extent of reaction was calculated from the analysis of the solid products by X-ray diffraction and, in the case of the experiments in vacuum, from the amount of carbon dioxide evolved from the system also. ��� In vacuum, the monoferrite SrFe2O4 results from the direct reaction of strontium carbonate and iron(III) oxide at comparatively low temperatures, while the hexaferrite SrFe12O19 is formed by the reaction of Sr2Fe2O4 with iron(III) oxide at higher temperatures. The formation of the ferrite Sr2Fe2O5 depends upon the prevailing atmosphere, since this compound was present only as an intermediate phase when the experiments were carried out in air and not in vacuum. Only three compounds of strontium, iron, and oxygen were found, namely the ferrites SrFe2O4, Sr2Fe2O5, and SrFe12O19. ��� The observataions appear to be explicable in terms of Tammann temperatures.

Real-time synchrotron powder X-ray diffraction study of the antisite defect formation during sub- and supercritical synthesis of LiFePO4and LiFe1−xMnxPO4nanoparticles

2011 ◽  
Vol 44 (2) ◽  
pp. 287-294 ◽  
Author(s):  
Kirsten Jensen ◽  
Mogens Christensen ◽  
Christoffer Tyrsted ◽  
Bo Brummerstedt Iversen
Keyword(s):  
Low Temperatures ◽  
Defect Formation ◽  
Intermediate Phase ◽  
Antisite Defect ◽  
X Ray Diffraction ◽  
X Ray ◽  
Manganese Doping ◽  
Antisite Defects ◽  
Supercritical Synthesis

In situsynchrotron powder X-ray diffraction (PXRD) is used to study the formation of LiFePO4nanoparticles during hydrothermal synthesis from LiOH, H3PO4, and two different iron precursors, FeSO4and (NH4)2Fe(SO4)2. Furthermore, the synthesis of Li(Fe1−xMnx)PO4(x= 0.25, 0.50 and 0.75) from LiOH, H3PO4and FeSO4/MnSO4is studied. The reactions involve an unknown intermediate phase, which is not the previously observed intermediate NH4FePO4·H2O. The intermediate phase quickly transforms into LiFePO4and Li(Fe1−xMnx)PO4even at rather low temperatures. The presence of ammonium enhances the formation of LiFePO4, and it also leads to a significant reduction in the concentration of Li–Fe antisite defects. Thein situPXRD technique allows one to follow the influence of time, temperature and manganese doping on the antisite defect concentration, and it is shown that even under supercritical conditions a reaction time of several minutes is required to suppress the defects. This makes flow synthesis of defect-free LiFePO4and Li(Fe1−xMnx)PO4nanoparticles challenging.

Nano-Folded Gold Electrocatalysts Enhance the Selectivity of Carbon Dioxide Reduction

2019 ◽  
Author(s):  
Kam Sang Kwok ◽  
Yuxuan Wang ◽  
Michael Cao ◽  
Hao Shen ◽  
Weinan Xu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Mass Transport ◽  
Gold Film ◽  
X Ray Diffraction ◽  
Thin Gold Film ◽  
Faradaic Efficiency ◽  
X Ray ◽  
Transmission Electron ◽  
Carbon Monoxide Formation ◽  
Catalytic Interfaces

<p>The local structure and geometry of catalytic interfaces can influence the selectivity of chemical reactions. Here, using a pre-strained polymer, we uniaxially compress a thin gold film to form a nano-folded catalyst. We observe two kinds of folds and can tune the ratio of loose to tight folds by varying the extent of pre-strain in the polymer. We characterize the nano-folded catalysts using x-ray diffraction, scanning, and transmission electron microscopy. We observe grain reorientation and coarsening in the nano-folded gold catalysts. Electroreduction of carbon dioxide with these nano-folded catalysts reveals an enhancement of Faradaic efficiency for carbon monoxide formation by a factor of about four. This result suggests that electrolyte mass transport limitations and an increase of the local pH in the tight folds of the catalyst outweigh the effects of alterations in grain characteristics. Together, our studies demonstrate that nano-folded geometries can significantly alter grain characteristics, mass transport, and catalytic selectivity. </p>

The Evaluation of TiTe2 as a Diffusion Barrier in the Formation of Low Thermal Conductivity Nanolaminates with Bi2Te3 and Sb2Te3

2010 ◽  
Vol 74 ◽  
pp. 38-47
Author(s):  
Clay Mortensen ◽  
Paul Zschack ◽  
David C. Johnson
Keyword(s):  
Thermal Conductivity ◽  
Diffusion Barrier ◽  
Self Assembly ◽  
Low Temperatures ◽  
Annealing Temperature ◽  
The Self ◽  
High Angle ◽  
X Ray Diffraction ◽  
Amorphous Precursor ◽  
X Ray

The evolution of designed [(Ti-Te)]x[(Sb-Te)]y, [(Bi-Te)]x[(Sb-Te)]y, [(Ti-Te)]w[(Bi-Te)]x[(Sb-Te)]y and [(Ti-Te)]w[(Bi-Te)]x[(Ti-Te)]y[(Sb-Te)]z precursors were followed as a function of annealing temperature and time using both low and high angle x-ray diffraction techniques to probe the self assembly into nanolaminate materials. The [(Bi-Te)]x[(Sb-Te)]y precursors were found to interdiffuse at low temperatures to form a (BixSb1-x)2Te3 alloy. The [(Ti-Te)]x[(Bi-Te)]y and [(Ti-Te)]x[(Sb-Te)]y precursors formed ordered nanolaminates [{(TiTe2)}1.35]x[Bi2Te3]y and [{(TiTe2)}1.35]x[Sb2Te3]y respectively. The [(Ti-Te)]w[(Bi-Te)]x[(Sb-Te)]x precursors formed [{(TiTe2)}1.35]w[(Bi0.5Sb0.5)2Te3]2x nanolaminates on annealing, as the bismuth and antimony layers interdiffused. Over the range of TiTe2 thicknesses used in [(Ti-Te)]w[(Bi-Te)]x[(Ti-Te)]y[(Sb-Te)]z precursors, Bi and Sb were found to interdiffuse through the 2-4 nm thick Ti-Te layers, resulting in the formation of (BixSb1-x)2Te3 alloy layers as part of the final nanolaminated products. When the Bi-Te and Sb-Te thicknesses were equal in the amorphous precursors, symmetric [{(TiTe2)}1.35]m[(Bi0.5Sb0.5)2Te3]n nanolamiantes were formed. When the thicknesses of Bi-Te and Sb-Te layers were not equal in the amorphous precursor, asymmetric [(TiTe2)1.35]m[(BixSb1-x)2Te3]n[(TiTe2)1.35]m[(BixSb1-x)2Te3]p nanolaminates were formed. These results imply that to form (A)w(B)x(C)y nanolaminates using designed layered precursors all three components must be immiscible. To form (A)x(B)y(A)x(C)z nanolaminates, the components must be immiscible or the precursor to the A component and the A component itself must be an effective interdiffusion barrier preventing B and C from mixing.

Single Crystal X-ray Diffraction Studies of Carbon Dioxide and Fuel-Related Gases Adsorbed on the Small Pore Scandium Terephthalate Metal Organic Framework, Sc2(O2CC6H4CO2)3

Langmuir ◽  
2009 ◽  
Vol 25 (6) ◽  
pp. 3618-3626 ◽  
Author(s):  
Stuart R. Miller ◽  
Paul A. Wright ◽  
Thomas Devic ◽  
Christian Serre ◽  
Gérard Férey ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Single Crystal ◽  
Metal Organic Framework ◽  
X Ray Diffraction ◽  
X Ray ◽  
Small Pore ◽  
Metal Organic ◽  
Organic Framework

An X-ray scattering study on inverted Ge–Si huts grown at low temperatures

2004 ◽  
Vol 19 (4) ◽  
pp. 347-351
Author(s):  
J. Xu ◽  
X. S. Wu ◽  
B. Qian ◽  
J. F. Feng ◽  
S. S. Jiang ◽  
...  
Keyword(s):  
Low Temperatures ◽  
Lattice Strain ◽  
Lattice Mismatch ◽  
Grazing Incidence ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Scattering ◽  
Transmission Electron ◽  
Large Lattice ◽  
Scattering Study

Ge–Si inverted huts, which formed at the Si∕Ge interface of Si∕Ge superlattice grown at low temperatures, have been measured by X-ray diffraction, grazing incidence X-ray specular and off-specular reflectivities, and transmission electron microscopy (TEM). The surface of the Si∕Ge superlattice is smooth, and there are no Ge–Si huts appearing on the surface. The roughness of the surfaces is less than 3 Å. Large lattice strain induced by lattice mismatch between Si and Ge is found to be relaxed because of the intermixing of Ge and Si at the Si∕Ge interface.

PREPARATION OF ANTIMONY-PLATINUM SURFACE ALLOY ELECTRODE BY ATOM DIFFUSION IN THE SOLID PHASE

2006 ◽  
Vol 20 (25n27) ◽  
pp. 3999-4004
Author(s):  
HIROSHI MATSUI ◽  
KAZUFUMI WATANABE
Keyword(s):  
Diffraction Pattern ◽  
Low Temperatures ◽  
Solid Phase ◽  
Electrochemical Measurement ◽  
X Ray Diffraction ◽  
Platinum Surface ◽  
X Ray ◽  
Atom Diffusion ◽  
Heat Treated ◽  
Titanium Substrates

Antimony-platinum bilayers were prepared on titanium substrates by the two-step electrodeposition in the usual baths, and then surface alloys were formed by the atom diffusion in the solid phase. The simple antimony layer was little influenced by the substrate in both the measurements of X-ray diffraction and the i - E characteristic in a sulfuric acid solution. Regarding the bilayers, the catalytic activity in hydrogen evolution reaction was very sensitive to the presence of platinum, while the hydrogen adsorbability was quite insensitive. An interaction between antimony and platinum was confirmed by the appearance of a new dissolution wave in the electrochemical measurement and the occurrence of a new diffraction in the X-ray diffraction pattern after the heat-treatment of about 400°C. Although the new diffraction disagreed with any of the reported alloys, clear diffraction pattern of PtSb 2 alloy was observed, when the bilayers were heat-treated at about 600°C for one hour. Considering the penetration depth of X-ray, the alloying of antimony and platinum seems to occur also at low temperatures at least at the top surface.

Magnetic Properties of Sputtered Fe-O and Co-O Thin Films

1995 ◽  
Vol 403 ◽  
Author(s):  
D. V. Dimitrov ◽  
A. S. Murthy ◽  
G. C. Hadjipanayis ◽  
C. P. SWANN
Keyword(s):  
Grain Size ◽  
Low Temperatures ◽  
Room Temperature ◽  
Oxide Films ◽  
X Ray Diffraction ◽  
Dc Magnetron Sputtering ◽  
Large Shift ◽  
X Ray ◽  
Grain Size And Shape ◽  
Spherical Grains

AbstractFe-O and Co-O films were prepared by DC magnetron sputtering in a mixture of Ar and O2 gases. By varying the oxygen to argon ratio, oxide films with stoichiometry FeO, Fe3O4, α-Fe2O3, CoO and Co3O4 were produced. TEM studies showed that the Fe – oxide films were polycrystalline consisting of small almost spherical grains, about 10 nm in size. Co-O films had different microstructure with grain size and shape dependent on the amount of oxygen. X-ray diffraction studies showed that the grains in Fe-O films were randomly oriented in contrast to Co-O films in which a <111> texture was observed. Pure FeO and α-Fe2O3 films were found to be superparamagnetic at room temperature but strongly ferromagnetic at low temperatures in contrast to the antiferromagnetic nature of bulk samples. A very large shift in the hysteresis loop, about 3800 Oe, was observed in field cooled Co-CoO films indicating the presence of a large unidirectional exchange anisotropy.

A Comparative Study of GaN Films Grown on Different Faces of Sapphire by ECR-Assisted MBE

1992 ◽  
Vol 242 ◽  
Author(s):  
T. D. Moustakas ◽  
R. J. Molnar ◽  
T. Lei ◽  
G. Menon ◽  
C. R. Eddy
Keyword(s):  
Surface Morphology ◽  
Low Temperatures ◽  
Smooth Surface ◽  
Growth Process ◽  
X Ray Diffraction ◽  
Epitaxial Relationship ◽  
X Ray ◽  
Sapphire Substrates ◽  
Growth Method ◽  
Step Growth

ABSTRACTGaN films were grown on c-plane (0001), a-plane (1120) and r-plane (1102) sapphire substrates by the ECR-assisted MBE method. The films were grown using a two-step growth process, in which a GaN buffer is grown first at relatively low temperatures and the rest of the film is grown at higher temperatures. RHEED studies indicate that this growth method promotes lateral growth and leads to films with smooth surface morphology. The epitaxial relationship to the substrate, the crystalline quality and the surface morphology were investigated by RHEED, X-ray diffraction and SEM studies.

A new stacking variant of Na2Pt(OH)6

2018 ◽  
Vol 73 (11) ◽  
pp. 831-836 ◽  
Author(s):  
Gohil S. Thakur ◽  
Hans Reuter ◽  
Claudia Felser ◽  
Martin Jansen
Keyword(s):  
Oxygen Pressure ◽  
Title Compound ◽  
Structure Type ◽  
Direct Reaction ◽  
Solid Residue ◽  
X Ray Diffraction ◽  
X Ray ◽  
Edge Distance ◽  
Naoh Solution

AbstractA new stacking variant of sodium hexa-hydroxo platinate(IV), Na2Pt(OH)6, was synthesized and its structure elucidated through X-ray diffraction. The new polymorph was prepared by direct reaction of PtO2 with an excess of NaOH solution applying elevated oxygen pressure at 300°C. The structure consists of layers of edge sharing Pt(OH)6 and Na(OH)6 octahedra. These layers are separated by an edge-to-edge distance of ~2.4 Å. The packing of the hydroxide ions corresponds to the hcp sequence, the title compound thus may be regarded a cation ordered variant of the Brucite structure type. During heating above T~300°C all constitutional water is released, and anhydrous Na2PtO3 remains as the solid residue.

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