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

2016 ◽  
Vol 18 (6) ◽  
pp. 4617-4626 ◽  
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.

Polymorphic transformations and thermal expansion of some modifications in Ag1.5Cu0.5Se and Ag0.4Cu1.6Se

2019 ◽  
Vol 33 (23) ◽  
pp. 1950271 ◽  
Author(s):  
Y. I. Aliyev ◽  
Y. G. Asadov ◽  
A. O. Dashdemirov ◽  
R. D. Aliyeva ◽  
T. G. Naghiyev ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Diffraction Method ◽  
Lattice Parameters ◽  
X Ray Diffraction ◽  
Polymorphic Transformations ◽  
X Ray

The Ag[Formula: see text]Cu[Formula: see text]Se and Ag[Formula: see text]Cu[Formula: see text]Se compounds have been synthesized and grown as single crystals. High-temperature X-ray diffraction method was used to study polymorphic transformations. It is shown that the Ag[Formula: see text]Cu[Formula: see text]Se crystals of high-temperature FCC modification are decomposed into Ag2Se and AgCuSe when the temperature decreases below T = 488 K and Ag[Formula: see text]Cu[Formula: see text]Se is decomposed into Cu2Se and AgCuSe when the temperature decreases below T = 540 K. Transformations in both compounds are reversible. Crystalline parameters are obtained and the temperature dependence of the lattice parameters for each phase is built.

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

MRS Advances ◽  
2016 ◽  
Vol 1 (62) ◽  
pp. 4133-4137 ◽  
Author(s):  
E. Epifano ◽  
R. C. Belin ◽  
J-C Richaud ◽  
R. Vauchy ◽  
M. Strach ◽  
...  
Keyword(s):  
High Temperature ◽  
Lattice Parameter ◽  
Minor Actinide ◽  
Controlled Atmosphere ◽  
X Ray Diffraction ◽  
X Ray ◽  
Binary Phase Diagrams ◽  
First Time ◽  
O Phase

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.

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.

scholarly journals In-situ study of high temperature corrosion kinetics of iron using a fast X-ray diffraction method

1993 ◽  
Vol 03 (C9) ◽  
pp. C9-461-C9-467 ◽  
Author(s):  
M. Juez-Lorenzo ◽  
V. Kolarik ◽  
N. Eisenreich ◽  
W. Engel ◽  
A. J. Criado
Keyword(s):  
High Temperature ◽  
Diffraction Method ◽  
High Temperature Corrosion ◽  
X Ray Diffraction ◽  
X Ray ◽  
In Situ Study ◽  
Corrosion Kinetics ◽  
Kinetics Of

Determination of thermal expansion of KCaI3 using in-situ high temperature powder X-ray diffraction

2018 ◽  
Vol 212 ◽  
pp. 161-166 ◽  
Author(s):  
Adam C. Lindsey ◽  
Matthew Loyd ◽  
Maulik K. Patel ◽  
Ryan Rawl ◽  
Haidong Zhou ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
X Ray Diffraction ◽  
X Ray

Thermal behaviour of alum-(K) KAl(SO4)2·12H2O from in situ laboratory high-temperature powder X-ray diffraction data: thermal expansion and modelling of the sulfate orientational disorder

2015 ◽  
Vol 79 (1) ◽  
pp. 157-170 ◽  
Author(s):  
Paolo Ballirano
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Diffraction Data ◽  
Bond Valence ◽  
X Ray Diffraction ◽  
Orientational Disorder ◽  
X Ray ◽  
Disorder Parameter ◽  
Bond Valence Sum

AbstractThe present work analyses the thermal behaviour of alum-(K), KAl(SO4)2·12H2O, by in situ laboratory high-temperature powder X-ray diffraction data from 303 K to melting, which starts at 355 K and is completed, due to kinetics, at 359 K. The calculated a0 linear thermal expansion coefficient is of 14.68(11) × 10–6 K–1 within the investigated thermal range. The k disorder parameter, describing the extension of the orientational disorder of the sulfate group, has been found to decrease from ∼0.70 to ∼0.65 just before melting. It has been demonstrated that the occurrence of the disorder implies the coexistence of K+ ions in both six- and seven-fold coordination. This is necessary for assigning a reasonable bond-valence sum of 0.81 valence units (vu) to the 'average' K+ ion a instead of 0.66 vu, which is obtained in the case of six-fold coordination alone. We can describe the temperature dependence of k from 93–355 K by means of the empirical equation k = 0.798(12) + 2.5(11) × 10–4 T – 1.9(2) × 10–6T2, which includes reference low-temperature data. Bond-valence analysis has shown that, on cooling, an increase of the k disorder parameter and shortening of the K–O2 bond distance act together to maintain constancy in the bond-valence sum at the K site, stabilizing the structure. Therefore, the need for keeping the 'average' K+ ion at a reasonable bond-valence sum appears to be the driving force for the ordering process involving the sulfate group.

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

2017 ◽  
Vol 32 (3) ◽  
pp. 168-174 ◽  
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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