scholarly journals Reduction of titanium oxide in the presence of nickel by nonequilibrium hydrogen gas

2009 ◽  
Vol 24 (7) ◽  
pp. 2391-2399 ◽  
Author(s):  
Hidehiro Sekimoto ◽  
Tetsuya Uda ◽  
Yoshitaro Nose ◽  
Shigeo Sato ◽  
Hiroaki Kakiuchi ◽  
...  
Keyword(s):  
Low Temperature ◽  
Relaxation Process ◽  
Reduction Potential ◽  
Hydrogen Plasma ◽  
Equilibrium Phase ◽  
Hydrogen Gas ◽  
X Ray Diffraction ◽  
Energy Process ◽  
X Ray ◽  
The Difference

We investigated the reduction of TiO2 in the presence of Ni by nonequilibrium hydrogen gas, including low-temperature hydrogen plasma at 800 °C and supercooled monatomic hydrogen at 1000 °C. TiO2 was reduced to Ti2O3, which is not in equilibrium phase, by low-temperature hydrogen plasma. The results of x-ray diffraction and energy dispersive x-ray analysis in experiments at 1000 °C indicate that the thermodynamical reduction potential of supercooled monatomic hydrogen is almost the same as atmospheric hydrogen gas. However, the wide Ti3O5 layer formed only in the case of the reduction at 1000 °C by supercooled monatomic hydrogen. With these experimental facts, we speculate that the reduction mechanism by nonequilibrium hydrogen consists of two steps; the releasing energy process and the relaxation process. We can explain the difference of reduction products by nonequilibrium hydrogen gas on the assumption of the rate of the relaxation process between 800 and 1000 °C.

Study of Polymeric Crude Oil Fluid Improver Crystallinity

2011 ◽  
Vol 236-238 ◽  
pp. 582-585
Author(s):  
Hong Zhang ◽  
Wen Fa Xiao
Keyword(s):  
Low Temperature ◽  
Crude Oil ◽  
Pour Point ◽  
Close Correlation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Polymer Fluid ◽  
Wax Crystal ◽  
The Difference ◽  
Fluid Behaviour

The characteristic groups of polymer were analyzed by the IR spectrometrer. The crystallinity of different style wax crystal and the fluid improver additive(FIA) were measured by the X-ray diffraction analysis. The results showed crystallinity of wax crystal was close correlation with the polymer fluid improver and the change of wax crystal dispersibilty will be caused by the difference of crystallinity which make change of pour point depressing behaviour of the crude oil. At the same time found when crystallinity of the wax crystal was match with the additive the wax crystal dispersibilty and pour point depressing and viscosity depressing will change well that was proved by fluid behaviour improving at low temperature of crude oil system.

Antiphase Boundaries in Ordered Ni3FE Crystals

1969 ◽  
Vol 27 ◽  
pp. 62-63
Author(s):  
Y. H. Liu
Keyword(s):  
Domain Size ◽  
Antiphase Domain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Hardening Mechanism ◽  
Superlattice Structure ◽  
Disordered Phase ◽  
Domain Boundaries ◽  
Atomic Scattering ◽  
The Difference

Ordered Ni3Fe crystals possess a LI2 type superlattice similar to the Cu3Au structure. The difference in slip behavior of the superlattice as compared with that of a disordered phase has been well established. Cottrell first postulated that the increase in resistance for slip in the superlattice structure is attributed to the presence of antiphase domain boundaries. Following Cottrell's domain hardening mechanism, numerous workers have proposed other refined models also involving the presence of domain boundaries. Using the anomalous X-ray diffraction technique, Davies and Stoloff have shown that the hardness of the Ni3Fe superlattice varies with the domain size. So far, no direct observation of antiphase domain boundaries in Ni3Fe has been reported. Because the atomic scattering factors of the elements in NijFe are so close, the superlattice reflections are not easily detected. Furthermore, the domain configurations in NioFe are thought to be independent of the crystallographic orientations.

Micro X-Ray Diffraction Study of Polycrystalline MgB 2 Wire and Evaluation of Carbon Doping Effect Via Low-Temperature Sintering

2019 ◽  
Author(s):  
Minoru Maeda ◽  
Dipak Patel, Dr. ◽  
Hiroaki Kumakura, Dr. ◽  
Gen Nishijima, Dr. ◽  
Akiyoshi Matsumoto, Dr. ◽  
...  
Keyword(s):  
Low Temperature ◽  
Diffraction Study ◽  
Carbon Doping ◽  
Doping Effect ◽  
Low Temperature Sintering ◽  
X Ray Diffraction ◽  
X Ray

The Application of X-Ray Diffraction at Elevated Temperatures to Study the Mechanism of Formation of Sodium Tripolyphosphate

1961 ◽  
Vol 5 ◽  
pp. 276-284
Author(s):  
E. L. Moore ◽  
J. S. Metcalf
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Amorphous Phase ◽  
Elevated Temperatures ◽  
Sodium Tripolyphosphate ◽  
X Ray Diffraction ◽  
Mechanism Of Formation ◽  
X Ray ◽  
Temperature Form ◽  
High Temperature Form

AbstractHigh-temperature X-ray diffraction techniques were employed to study the condensation reactions which occur when sodium orthophosphates are heated to 380°C. Crystalline Na4P2O7 and an amorphous phase were formed first from an equimolar mixture of Na2HPO4·NaH2PO4 and Na2HPO4 at temperatures above 150°C. Further heating resulted in the formation of Na5P3O10-I (high-temperature form) at the expense of the crystalline Na4P4O7 and amorphous phase. Crystalline Na5P3O10-II (low-temperature form) appears after Na5P3O10-I.Conditions which affect the yield of crystalline Na4P2O7 and amorphous phase as intermediates and their effect on the yield of Na5P3O10 are also presented.

scholarly journals X-ray diffraction analysis of kaolin M1 and M2 via the Williamson–Hall and Warren–Averbach methods

2021 ◽  
pp. 174751982098472
Author(s):  
Lalmi Khier ◽  
Lakel Abdelghani ◽  
Belahssen Okba ◽  
Djamel Maouche ◽  
Lakel Said
Keyword(s):  
Grain Size ◽  
High Temperature ◽  
Low Temperature ◽  
Diffraction Analysis ◽  
Mechanical Resistance ◽  
X Ray Diffraction ◽  
Integral Breadth ◽  
X Ray ◽  
Mullite Phase

Kaolin M1 and M2 studied by X-ray diffraction focus on the mullite phase, which is the main phase present in both products. The Williamson–Hall and Warren–Averbach methods for determining the crystallite size and microstrains of integral breadth β are calculated by the FullProf program. The integral breadth ( β) is a mixture resulting from the microstrains and size effect, so this should be taken into account during the calculation. The Williamson–Hall chart determines whether the sample is affected by grain size or microstrain. It appears very clearly that the principal phase of the various sintered kaolins, mullite, is free from internal microstrains. It is the case of the mixtures fritted at low temperature (1200 °C) during 1 h and also the case of the mixtures of the type chamotte cooks with 1350 °C during very long times (several weeks). This result is very significant as it gives an element of explanation to a very significant quality of mullite: its mechanical resistance during uses at high temperature remains.

Silicate-germanate K2Y[(Si3Ge)O10(OH)] with unusual complex corrugated layer and its correlation to ring silicate gerenite and chain silicate chkalovite

2020 ◽  
Vol 235 (4-5) ◽  
pp. 167-172
Author(s):  
Anastasiia P. Topnikova ◽  
Elena L. Belokoneva ◽  
Olga V. Dimitrova ◽  
Anatoly S. Volkov ◽  
Leokadiya V. Zorina
Keyword(s):  
Low Temperature ◽  
Cross Section ◽  
Complex Anion ◽  
Diffraction Experiment ◽  
X Ray Diffraction ◽  
Unit Cell Parameters ◽  
X Ray ◽  
Cell Parameters ◽  
Chain Silicate ◽  
Novel Complex

AbstractA new silicate-germanate K2Y[(Si3Ge)O10(OH)] was synthesized hydrothermally in a system Y2O3:GeO2:SiO2 = 1:1:2 (T = 280 °C; P = 90–100 atm.); K2CO3 was added to the solution as a mineralizer. Single-crystal X-ray diffraction experiment was carried out at low temperature (150 K). The unit cell parameters are a = 10.4975(4), b = 6.9567(2), c = 15.4001(6) Å, β = 104.894(4)°; V = 1086.86(7) Å3; space group is P 21/c. A novel complex anion is presented by corrugated (Si,Ge) tetrahedral layers connected by couples of YO6 octahedra into the mixed microporous framework with the channels along b and a axes, the maximal size of cross-section is ~5.6 Å. This structure has similarity with the two minerals: ring silicate gerenite (Ca,Na)2(Y,REE)3Si6O18 · 2H2O and chain silicate chkalovite Na2BeSi2O6. Six-member rings with 1̅ symmetry as in gerenite are distinguished in the new layer. They are mutually perpendicular to each other and connected by additional tetrahedra. Straight crossing chains in chkalovite change to zigzag four-link chains in the new silicate-germanate layer.

Local atomic structure in tetragonal pure ZrO2nanopowders

2010 ◽  
Vol 43 (2) ◽  
pp. 227-236 ◽  
Author(s):  
Leandro M. Acuña ◽  
Diego G. Lamas ◽  
Rodolfo O. Fuentes ◽  
Ismael O. Fábregas ◽  
Márcia C. A. Fantini ◽  
...  
Keyword(s):  
Tetragonal Phase ◽  
Local Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Structures ◽  
Crystallite Sizes ◽  
Exafs Study ◽  
The Difference ◽  
X Ray Absorption ◽  
Good Agreement

The local atomic structures around the Zr atom of pure (undoped) ZrO2nanopowders with different average crystallite sizes, ranging from 7 to 40 nm, have been investigated. The nanopowders were synthesized by different wet-chemical routes, but all exhibit the high-temperature tetragonal phase stabilized at room temperature, as established by synchrotron radiation X-ray diffraction. The extended X-ray absorption fine structure (EXAFS) technique was applied to analyze the local structure around the Zr atoms. Several authors have studied this system using the EXAFS technique without obtaining a good agreement between crystallographic and EXAFS data. In this work, it is shown that the local structure of ZrO2nanopowders can be described by a model consisting of two oxygen subshells (4 + 4 atoms) with different Zr—O distances, in agreement with those independently determined by X-ray diffraction. However, the EXAFS study shows that the second oxygen subshell exhibits a Debye–Waller (DW) parameter much higher than that of the first oxygen subshell, a result that cannot be explained by the crystallographic model accepted for the tetragonal phase of zirconia-based materials. However, as proposed by other authors, the difference in the DW parameters between the two oxygen subshells around the Zr atoms can be explained by the existence of oxygen displacements perpendicular to thezdirection; these mainly affect the second oxygen subshell because of the directional character of the EXAFS DW parameter, in contradiction to the crystallographic value. It is also established that this model is similar to another model having three oxygen subshells, with a 4 + 2 + 2 distribution of atoms, with only one DW parameter for all oxygen subshells. Both models are in good agreement with the crystal structure determined by X-ray diffraction experiments.

scholarly journals Photodeposition of Ag Nanocrystals onto TiO2 Nanotube Platform for Enhanced Water Splitting and Hydrogen Gas Production

2020 ◽  
Vol 2020 ◽  
pp. 1-11 ◽  
Author(s):  
Nur Aimi Jani ◽  
Choonyian Haw ◽  
Weesiong Chiu ◽  
Saadah Abdul Rahman ◽  
Poisim Khiew ◽  
...  
Keyword(s):  
Water Splitting ◽  
Gas Production ◽  
Hydrogen Gas ◽  
Current Work ◽  
Plasmonic Resonance ◽  
X Ray Diffraction ◽  
X Ray ◽  
Production Of Hydrogen ◽  
Production Activity ◽  
Ag Ncs

Current work reports the study of Ag nanocrystals (NCs) decorated doubly anodized (DA) TiO2 nanotubes (NTs) thin film as an efficient photoelectrode material for water splitting and photocatalytic hydrogen gas production. DA process has been shown to be capable of producing less defective NTs and creating additional spacious gaps in between NT bundles to allow efficient and uniform integration of Ag NCs. By employing photoreduction method, Ag NCs can be deposited directly onto NTs, where the size and density of coverage can be maneuvered by merely varying the concentration of Ag precursors. Field emission scanning electron microscope (FESEM) images show that the Ag NCs with controllable size are homogeneously decorated onto the walls of NTs with random yet uniform distribution. X-ray diffraction (XRD) results confirm the formation of anatase TiO2 NTs and Ag NCs, which can be well indexed to standard patterns. The decoration of metallic Ag NCs onto the surface of NTs demonstrates a significant enhancement in the photoconversion efficiency as compared to that of pristine TiO2 NTs. Additionally, the as-prepared nanocomposite film also shows improved efficiency when used as a photocatalyst platform in the production of hydrogen gas. Such improvement in the performance of water splitting and photocatalytic hydrogen gas production activity can be credited to the surface plasmonic resonance of Ag NCs present on the surface of the NTs, which renders improved light absorption and better charge separation. The current work can serve as a model of study for designing more advanced nanoarchitecture photoelectrode for renewable energy application.

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