In-situ High Temperature X-ray Diffraction Study of the Am-O System

ABSTRACTIn the frame of minor actinide recycling, (U,Am)O2 are promising transmutation targets. To assess the thermodynamic properties of the U-Am-O system, it is essential to have a thorough knowledge of the binary phase diagrams, which is difficult due to the lack of thermodynamic data on the Am-O system. Nevertheless, an Am-O phase diagram modelling has been recently proposed by Gotcu. Here, we show a recent investigation of the Am-O system using in-situ High Temperature X-ray Diffraction under controlled atmosphere. By coupling our experimental results with the thermodynamic calculations based on the Gotcu model, we propose for the first time a relation between the lattice parameter and the departure from stoichiometry.

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Oxygen-Induced Reversible Structural Change of Supported fine Silver Particles Observed by In Situ Optical Absorption and X-ray Diffraction

MRS Proceedings ◽

10.1557/proc-195-31 ◽

1990 ◽

Vol 195 ◽

Author(s):

Akihisa Yanase ◽

Hiroshi Komiyama ◽

Kazunobu Tanaka

Keyword(s):

Optical Absorption ◽

Surface Stress ◽

Lattice Parameter ◽

Silver Particles ◽

X Ray Diffraction ◽

X Ray ◽

Ambient Gases ◽

First Time ◽

Shape Of Particles

ABSTRACTIn situ measurements of optical absorption and x-ray diffraction for small supported silver particles were performed under defined atmospheres at temperatures below 723 K. We found, for the first time, reversible changes both in optical absorption spectrum and lattice parameter of silver particles against the cyclic exchange of ambient gases between 5% H2/He and 1% 02/He. The present data indicate that the adsorption of oxygen results in a reduction in surface stress of silver particles, leading to a change in the shape of particles.

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High-temperature X-ray diffraction and thermal expansion of nanocrystalline and coarse-crystalline acanthite α-Ag2S and argentite β-Ag2S

Physical Chemistry Chemical Physics ◽

10.1039/c5cp07224g ◽

2016 ◽

Vol 18 (6) ◽

pp. 4617-4626 ◽

Cited By ~ 37

Author(s):

S. I. Sadovnikov ◽

A. I. Gusev ◽

A. V. Chukin ◽

A. A. Rempel

Keyword(s):

Thermal Expansion ◽

High Temperature ◽

Diffraction Method ◽

Silver Sulfide ◽

X Ray Diffraction ◽

X Ray ◽

First Time

An in situ study of thermal expansion of polymorphic phases of coarse-crystalline and nanocrystalline silver sulfide – monoclinic acanthite α-Ag2S and cubic argentite β-Ag2S – has been carried out for the first time using the high-temperature X-ray diffraction method.

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In situ high-temperature X-ray diffraction studies of reduction of K2CrO4 and the formation of KxCrOy compounds

Powder Diffraction ◽

10.1017/s0885715617000690 ◽

2017 ◽

Vol 32 (3) ◽

pp. 168-174 ◽

Cited By ~ 3

Author(s):

Shu-ting Liang ◽

Hong-ling Zhang ◽

Min-ting Luo ◽

Yu-lan Bai ◽

Hong-bin Xu ◽

...

Keyword(s):

Fourier Transform ◽

High Temperature ◽

Hydrogen Reduction ◽

Potassium Chromate ◽

Crystalline Material ◽

Reduction Mechanism ◽

X Ray Diffraction ◽

X Ray ◽

First Time

In this work, the reduction mechanism of potassium chromate (K2CrO4) was investigated via in situ high-temperature X-ray diffraction coupled with Fourier transform infrared spectroscopy. During the hydrogen reduction of K2CrO4, the formation of K3CrO4, KCrO2, and KxCrO2 were detected for the first time. The study discovered that K2CrO4 was firstly reduced to K3CrO4 and an amorphous Cr(III) intermediate product at low temperature (400–500 °C). Moreover, the K3CrO4 was the only crystalline material at this stage. As the temperature increased, a stabilized amorphous CrOOH was formed. At a high temperature (550–700 °C), KCrO2 was generated. Interestingly, a portion of KCrO2 was spontaneously decomposed during the hydrogen reduction, accompanying by the formation of K0.7CrO2. Finally, the results clearly illustrated the reduction mechanism of K2CrO4: K2CrO4 → K3CrO4 → amorphous intermediate → KCrO2.

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