Effect of a Tetravalent Dopant, Th4+ on the Oxidation of Uranium Dioxide

2005 ◽  
Vol 277-279 ◽  
pp. 654-659 ◽  
Author(s):  
Yeong Keong Ha ◽  
Jong Goo Kim ◽  
Yeong Jae Park ◽  
Won Ho Kim
Keyword(s):  
Oxidation Reaction ◽  
Oxidation Kinetic ◽  
Lattice Parameter ◽  
Air Oxidation ◽  
X Ray Diffraction ◽  
Kinetic Curves ◽  
X Ray ◽  
A Value ◽  
Formal Charge ◽  
Diffraction Patterns

The effect of a tetravalent dopant, Th4+, on the oxidation of UO2 was investigated using a thermogravimetry and X-ray diffraction analysis. Th-doped UO2’s with various dopant contents were prepared and their oxidation kinetic curves were obtained from the weight gains during air-oxidation. For the first oxidation step from (U1-yThy)O2 to (U1-yThy)4O9, the oxidation kinetic curves showed the same gradient regardless of the Th content. The inhibition of the oxidation reaction occurred dominantly in the second step, from (U1-yThy)4O9 to (U1-yThy)3O8. At the plateau of the second stage, the calculated O/M values and the X-ray diffraction patterns revealed that the O/M ratio was decreased with an increase of Th content. The relationship between the mean formal charge and the composition showed that the oxidation to (U1-yThy)3O8 proceeds within a certain limit. The lattice parameter of the initial material seems to affect the oxidation rate of the first step. And the oxidation reaction stopped when the average formal charge of the U atoms reached a value of 5.3.

scholarly journals Elaboration of nitride thin films by reactive sputtering

2006 ◽  
Vol 59 (2) ◽  
pp. 225-232 ◽  
Author(s):  
Pierre Yves Jouan ◽  
Arnaud Tricoteaux ◽  
Nicolas Horny
Keyword(s):  
Thin Films ◽  
Compressive Stress ◽  
Bias Voltage ◽  
Substrate Surface ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
X Ray ◽  
A Value ◽  
Dc Reactive Magnetron Sputtering ◽  
Nitrogen Contents

The aim of this paper is first a better understanding of DC reactive magnetron sputtering and its implications, such as the hysteresis effect and the process instability. In a second part, this article is devoted to an example of specific application: Aluminium Nitride. AlN thin films have been deposited by reactive triode sputtering. We have studied the effect of the nitrogen contents in the discharge and the RF bias voltage on the growth of AlN films on Si(100) deposited by triode sputtering. Stoichiometry and crystal orientation of AlN films have been characterized by means of Fourier-transform infrared spectroscopy, X-ray diffraction and secondary electron microscopy. Dense and transparent AlN layers were obtained at high deposition rates. These films have a (002) orientation whatever the nitrogen content in the discharge, but the best crystallised ones are obtained at low value (10%). A linear relationship was observed between the AlN lattice parameter "c" (perpendicular to the substrate surface) and the in-plane compressive stress. Applying an RF bias to the substrate leads to a (100) texture, and films become amorphous. Moreover, the film's compressive stress increases up to a value of 8GPa before decreasing slowly as the bias voltage increases.

Structural and optical properties of Ba(Co1−xZnx)SiO4 (x = 0.2, 0.4, 0.6, 0.8)

2019 ◽  
Vol 34 (3) ◽  
pp. 242-250 ◽  
Author(s):  
J. Anike ◽  
R. Derbeshi ◽  
W. Wong-Ng ◽  
W. Liu ◽  
D. Windover ◽  
...  
Keyword(s):  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Powder Diffraction File ◽  
Visible Absorption ◽  
X Ray ◽  
Lattice Volume ◽  
Uv Visible ◽  
Diffraction Patterns ◽  
Pattern Determination ◽  
Bright Blue

Structural characterization and X-ray reference powder pattern determination have been conducted for the Co- and Zn-containing tridymite derivatives Ba(Co1−xZnx)SiO4 (x = 0.2, 0.4, 0.6, 0.8). The bright blue series of Ba(Co1−xZnx)SiO4 crystallized in the hexagonal P63 space group (No. 173), with Z = 6. While the lattice parameter “a” decreases from 9.126 (2) Å to 9.10374(6) Å from x = 0.2 to 0.8, the lattice parameter “c” increases from 8.69477(12) Å to 8.72200(10) Å, respectively. Apparently, despite the similarity of ionic sizes of Zn2+ and Co2+, these opposing trends are due to the framework tetrahedral tilting of (ZnCo)O4. The lattice volume, V, remains comparable between 626.27 Å3 and 626.017 (7) Å3 from x = 0 to x = 0.8. UV-visible absorption spectrum measurements indicate the band gap of these two materials to be ≈3.3 and ≈3.5 eV, respectively, therefore potential UV photocatalytic materials. Reference powder X-ray diffraction patterns of these compounds have been submitted to be included in the Powder Diffraction File (PDF).

Structural and electrical properties of Cu-doped Ni–Zn nanocrystalline ferrites for MLCI applications

2017 ◽  
Vol 31 (33) ◽  
pp. 1750318 ◽  
Author(s):  
D. Venkatesh ◽  
K. V. Ramesh
Keyword(s):  
Electrical Properties ◽  
Cation Distribution ◽  
Tetrahedral Site ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Structural And Electrical Properties ◽  
Phase Spinel ◽  
Diffraction Patterns

Polycrystalline Cu substituted Ni–Zn ferrites with chemical composition Ni[Formula: see text]Zn[Formula: see text]-Cu[Formula: see text]Fe2O4 (x = 0.00 to 0.25 in steps of 0.05) have been prepared by citrate gel autocombustion method. The samples for electrical properties have been sintered at 900[Formula: see text]C for 4 h. The X-ray diffraction patterns of all samples indicate the formation of single phase spinel cubic structure. The value of lattice parameter is decreases with increasing Cu concentration. The estimated cation distribution can be derived from X-ray diffraction intensity calculations and IR spectra. The tetrahedral and octahedral bond lengths, bond angles, cation–cation and cation–anion distances were calculated by using experimental lattice parameter and oxygen positional parameters. It is observed that Cu ions are distributed in octahedral site and subsequently Ni and Fe ions in tetrahedral site. The grain size of all samples has been calculated by Scanning Electron Microscopy (SEM) images. The variations in DC electrical resistivity and dielectric constant have been explained on the basis of proposed cation distribution.

Effect of the Dwell Temperature on Spark Plasma Sintered CaCu3Ti4O12

2012 ◽  
Vol 727-728 ◽  
pp. 982-987
Author(s):  
E. de Carvalho ◽  
Marcelo Bertolete ◽  
Izabel Fernanda Machado ◽  
E.N.S. Muccillo
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Lattice Parameter ◽  
Solid State Reactions ◽  
X Ray Diffraction ◽  
X Ray ◽  
Plasma Sintering ◽  
Spark Plasma ◽  
Diffraction Patterns ◽  
Scanning Electron

Polycrystalline CaCu3Ti4O12 ceramics were prepared by solid state reactions by spark plasma sintering (SPS) technique. In this study, the effects of the dwell temperature on structural, microstructural and dielectric properties of CaCu3Ti4O12 ceramics have been investigated. Powder mixtures were calcined at 900°C for 18 h before SPS consolidation. The dwell temperatures were 850, 900, 915 and 930°C. Sintered pellets were characterized by X-ray diffraction, scanning electron microscopy and impedance spectroscopy. X-ray diffraction patterns show evidences of a single-phase perovskite-type structure. The calculated lattice parameter is 7.40 Å. The hydrostatic density increases slightly with increasing dwell temperature. Scanning electron microscopy observations revealed a heterogeneous microstructure for all samples. The dielectric loss remains constant over a wide temperature range. The obtained permittivity is approximately 103 at 1 kHz. The increase of the dwell temperature is found to produce a brittle ceramic.

scholarly journals CRYSTAL STRUCTURE ANALYSIS OF CuCrO2 BASED ON XRD DATA USING GSAS SOFTWARE

2021 ◽  
Vol 4 (1) ◽  
pp. 7
Author(s):  
Lalu A. Didik ◽  
Muh. Wahyudi
Keyword(s):  
Reference Data ◽  
Measurement Data ◽  
Lattice Parameter ◽  
Crystal Structure Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
A Value ◽  
A Cell ◽  
Parameter Values

The synthesis of CuCrO2 crystals by mixing CuO and Cr2O3 has been carried out using the solid reaction method at a temperature of 1200 0C. The characterization of the structure used XRD and analyzed using GSAS software. The results of characterization using XRD showed that no other phase occurred. This is evidenced by the absence of other phases from the results of refinement of measurement data with reference data and a value of χ 2 which is 1.222. The lattice parameter values resulting from the refinement of the CuCrO2 X-ray diffraction pattern are a = b = 2.9715 Å and c = 17.1104 Å with a cell volume of 130.584 Å 3. In addition to the lattice parameter values, the distance between atoms was also obtained, both Cu - O, Cr - Cr, and Cr - O.

The Mixed Magnetic Property of Co0.76Cu0.74[Fe(CN)6]·7.5H2O

2018 ◽  
Vol 71 (11) ◽  
pp. 914
Author(s):  
Yanfang Xia ◽  
Min Liu ◽  
Duxin Li
Keyword(s):  
Magnetic Field ◽  
Magnetic Moment ◽  
Effective Magnetic Moment ◽  
Lattice Parameter ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
X Ray ◽  
Diffraction Patterns ◽  
Co Precipitation ◽  
The Magnetic Field

Co0.76Cu0.74[Fe(CN)6]·7.5H2O was prepared as a powder by a chemical co-precipitation method. The powder X-ray diffraction patterns were indexed to the typical face-centred cubic structure with the lattice parameter a 10.55(2) Å. The temperature dependence of the χ−1 curve obeys the Curie–Weiss law (χ = C/(T – θ)) in the temperature range of 180–300 K. According to Curie–Weiss law, the calculated θ value is −54.82 K. In the paramagnetic state at 300 K, the effective magnetic moment (μeff = (8χT)1/2) is 3.58 μB per formula unit. The calculated theoretical effective magnetic moment is 4.06 μB. The magnetic field cooling measurements under a 200 Oe applied magnetic field show that the saturation magnetization value at 2 K of the complex Co0.76Cu0.74[Fe(CN)6]·7.5H2O is 1.528 emu g−1.

Structural and Dielectric Analysis of La0.88Bi0.12Mn0.80Ni0.20O3 Composite

2021 ◽  
Vol 317 ◽  
pp. 35-45
Author(s):  
Aaliyawani Ezzerin Sinin ◽  
Walter Charles Primus ◽  
Zainal Abidin Talib ◽  
Chen Soo Kien ◽  
Abdul Halim Shaari ◽  
...  
Keyword(s):  
Dielectric Loss ◽  
Sintering Temperature ◽  
Solid State Reaction Method ◽  
Lattice Parameter ◽  
Rhombohedral Structure ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
X Ray ◽  
A Value ◽  
Electric Behavior

Composite La0.88Bi0.12Mn0.80Ni0.20O3 was synthesized using the conventional solid-state reaction method with sintering temperature of 1200 °C for 12 hours and the dielectric properties investigated. The X-ray diffraction result shows that the composite has a rhombohedral structure with lattice parameter of a = b = c = 5.5136 Ǻ. Scanning electron microscope shows grains with approximately from 0.8 to 5.4 μm in size with presence of voids. The dielectric permittivity, εʹ and dielectric loss, εʺ were measured in the range of 298 K to 473 K where both are temperature and frequency dependent. At 1 kHz to 100 kHz, the εʹ is around 10000 and the dielectric loss tangent, tan δ is below 1.5. The electric behavior of this composite is best represented by Quasi-dc model which consists of two universal capacitors in parallel. Parameters value from the fitting indicated that high correlations of electrons between inter and intra-clusters. The activation energy, Ea calculated from the conductivity of the sample gives a value of 0.116 eV. Vibrating sample magnetometer shows that the La0.88Bi0.12Mn0.80Ni0.20O3 has a magnetic coercivity, Hc of 36.109 G and retentivity, Br, valued 2.7504 x 10-3 emu/g.

Textured Superconducting Thin Films of Bismuth Cuprate by Laser Ablation Method

1989 ◽  
Vol 169 ◽  
Author(s):  
Ashok Kumar ◽  
L. Ganapathi ◽  
J. Narayan
Keyword(s):  
Thin Films ◽  
Laser Ablation ◽  
Bulk Material ◽  
Lattice Parameter ◽  
Superconducting Thin Films ◽  
X Ray Diffraction ◽  
X Ray ◽  
Laser Ablation Method ◽  
Zero Resistance ◽  
Diffraction Patterns

AbstractWe have prepared highly textured superconducting thin films from Bi1.5pb0.5Ca3Sr2Cu4Ox (2324) on (100) YS-ZrO2 (Yttria stabilized zirconia) and Bi1.5Pb0.5Ca2Sr2Cu3°x (2223) on LaAlC-3 (100) and MgO (100) substrates at 650°C by pulsed laser ablation method.These films showed 2212 type of phase of the (BiPb)2(Ca,Sr)n+1CunO2n+4+5 family with onset transition temperature ( Tc ) ~ 110 K, confirming our earlier observations of 110 K superconductivity in a n = 2 bulk material. Thin films deposited from 2324 bulk target on YS-Z1O2 showed zero resistance temperature (Tco ) of 68 K but post annealing for one hour at 400°C in oxygen improved Tco from 68 K to 82 K. Thin films from 2223 target on LaAlO3 ( 100 ) and MgO ( 100 ) exhibited a Tco of 65 K and 74 K respectively while onset remained the same at 110 K. Further annealing at 400°C for one hour in oxygen did not show any improvement in Tco. X-ray diffraction (XRD), scanning electron microscopy (SEM) and Rutherford backscattering (RBS) channeling studies were performed on these films for correlation between crystal structure, microstructure and superconducting properties. X-ray diffraction patterns indicated 2212 type phase with a= 5.39 Å and c=30.76 Å; preferential orientation of c-axis perpendicular to the substrate was observed. The lattice parameter and x-ray diffraction patterns were found to be invariant with annealing treatments.

Densification Behaviour of Nano-Size CeO2

2007 ◽  
Vol 555 ◽  
pp. 189-194 ◽  
Author(s):  
D. Djurović ◽  
Matvei Zinkevich ◽  
Snezana Bošković ◽  
V. Srot ◽  
Fritz Aldinger
Keyword(s):  
High Temperature ◽  
Redox Reaction ◽  
Lattice Parameter ◽  
Oxygen Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Densification Behaviour ◽  
Air Atmosphere ◽  
Diffraction Patterns ◽  
Lower Temperature

A nano-sized CeO2 powder was synthesized by a modified glycine nitrate process (MGNP). The synthesized powder was characterized by X-ray diffraction (XRD), the Brunauer Emmett Teller (BET) method, and transmission electron microscopy (TEM). The lattice parameter and crystallite size were determined by the Rietveld refinement of X-ray diffraction patterns. The shrinkage kinetics of the green body was continuously monitored in air and in oxygen atmospheres using a high temperature dilatometer up to 1500°C. During the high temperature sintering in air a redox reaction occurred (Ce4+ was partially reduced to Ce3+, and oxygen gas was released). The redox reaction influenced the sintering behaviour of CeO2, resulting in a decrease in density. On the basis of shrinkage kinetics data in oxygen atmosphere a master sintering curve for CeO2 was constructed. Using the concept of the master sintering curve, the densification behaviour in oxygen atmosphere was successfully predicted from early to final stages of sintering. During sintering of CeO2 at lower temperature in air atmosphere a significant contribution of the surface diffusion was observed.

Application of diffraction instrumental monitoring to the analysis of diffraction patterns from a Round Robin project on KCl

2001 ◽  
Vol 16 (1) ◽  
pp. 6-15 ◽  
Author(s):  
Giovanni Berti
Keyword(s):  
Cell Parameter ◽  
Direct Consequence ◽  
Lattice Parameter ◽  
Round Robin ◽  
X Ray Diffraction ◽  
X Ray ◽  
Standard Values ◽  
Instrumental Monitoring ◽  
Diffraction Patterns ◽  
Definition Of

The outcome of the analysis of data from a Round Robin on a KCl sample is reported. The research project has led to a definition of a working protocol for the treatment of X-ray diffraction data from powders (XRPD). The protocol is based on the method of “Diffraction Instrumental Monitoring” (DIM), whose main characteristics are briefly illustrated. When experimental data are referred to the expected standard values of the lattice parameter, the method enables comparison with data obtained from differing instrumentation found in different laboratories. Application of DIM to the KCl Round Robin demonstrates the ability of DIM to effectively evaluate systematic contribution. Accuracy on the cell parameter is obtained as a direct consequence; in this application, where the knowledge of the KCl d-spacing was not a problem, the accuracy of lattice parameter is a feedback for constraining the evaluation of the effective values of the experiment-related parameters.

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