scholarly journals High-temperature decomposition of Cu2BaSnS4 with Sn loss reveals newly identified compound Cu2Ba3Sn2S8

2020 ◽  
Vol 8 (22) ◽  
pp. 11346-11353
Author(s):  
José A. Márquez ◽  
Jon-Paul Sun ◽  
Helena Stange ◽  
Hasan Ali ◽  
Leo Choubrac ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Fluorescence Analysis ◽  
Decomposition Mechanism ◽  
Temperature Decomposition

The decomposition mechanism of Cu2BaSnS4 is studied by in situ diffraction and fluorescence analysis revealing “Sn loss” and Cu2Ba3Sn2S8 at high temperatures.

Stability of TaC precipitates in a Co–Re-based alloy being developed for ultra-high-temperature applications

2016 ◽  
Vol 49 (4) ◽  
pp. 1253-1265 ◽  
Author(s):  
Ralph Gilles ◽  
Debashis Mukherji ◽  
Lukas Karge ◽  
Pavel Strunz ◽  
Premysl Beran ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Gas Turbines ◽  
Volume Fraction ◽  
Turbine Blades ◽  
Alloy Development ◽  
Carbide Phases ◽  
Ultra High Temperature ◽  
Temperature Applications

Co–Re alloys are being developed for ultra-high-temperature applications to supplement Ni-based superalloys in future gas turbines. The main goal of the alloy development is to increase the maximum service temperature of the alloy beyond 1473 K,i.e.at least 100 K more than the present single-crystal Ni-based superalloy turbine blades. Co–Re alloys are strengthened by carbide phases, particularly the monocarbide of Ta. The binary TaC phase is stable at very high temperatures, much greater than the melting temperature of superalloys and Co–Re alloys. However, its stability within the Co–Re–Cr system has never been studied systematically. In this study an alloy with the composition Co–17Re–23Cr–1.2Ta–2.6C was investigated using complementary methods of small-angle neutron scattering (SANS), scanning electron microscopy, X-ray diffraction and neutron diffraction. Samples heat treated externally and samples heatedin situduring diffraction experiments exhibited stable TaC precipitates at temperatures up to 1573 K. The size and volume fraction of fine TaC precipitates (up to 100 nm) were characterized at high temperatures within situSANS measurements. Moreover, SANS was used to monitor precipitate formation during cooling from high temperatures. When the alloy is heated the matrix undergoes an allotropic phase transformation from the ∊ phase (hexagonal close-packed) to the γ phase (face-centred cubic), and the influence on the strengthening TaC precipitates was also studied within situSANS. The results show that the TaC phase is stable and at these high temperatures the precipitates coarsen but still remain. This makes the TaC precipitates attractive and the Co–Re alloys a promising candidate for high-temperature application.

High-Temperature In Situ Straining Experiments in the High-Voltage Electron Microscope

1998 ◽  
Vol 4 (3) ◽  
pp. 226-234 ◽  
Author(s):  
Ulrich Messerschmidt ◽  
Dietmar Baither ◽  
Martin Bartsch ◽  
Bernd Baufeld ◽  
Bert Geyer ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Oxide Dispersion Strengthened ◽  
Voltage Electron ◽  
Dislocation Plasticity ◽  
Transmission Electron ◽  
Macroscopic Deformation ◽  
Oxide Particles ◽  
Short Time

Design rules are described here for high-temperature straining stages for transmission electron microscopy. Temperatures above 1000°C can be attained by electron bombardment of the specimen grips. Thermal equilibrium can be reached in a short time by carrying off the heat by water cooling. Some applications of this stage are described. Ferroelastic deformation was observed at 1150°C in t′ and partially stabilized zirconia, which changes the microstructure for successive dislocation plasticity. In the oxide-dispersion-strengthened alloy INCOLOY MA 956, dislocations are impeded by oxide particles and move smoothly between the particles. At high temperatures, both the resting and traveling times control the average dislocation velocity. In MoSi2 single crystals of a soft orientation, dislocations with 1/2〈111〉 Burgers vectors are created in localized sources and move on {110} planes in a viscous manner. The dislocations in Al-Pd-Mn single quasicrystals are oriented in preferred crystallographic directions and move in a viscous way as well. On the basis of in situ observations, conclusions are drawn for interpreting macroscopic deformation behavior at high temperatures.

scholarly journals Method Development for High Temperature In-Situ Neutron Diffraction Measurements of Glass Crystallization on Cooling from Melt

MRS Advances ◽  
2019 ◽  
Vol 4 (17-18) ◽  
pp. 1009-1019 ◽  
Author(s):  
John McCloy ◽  
José Marcial ◽  
Brian Riley ◽  
Jörg Neuefeind ◽  
Jarrod Crum ◽  
...  
Keyword(s):  
High Temperature ◽  
Neutron Diffraction ◽  
High Temperatures ◽  
Method Development ◽  
Temperature Measurements ◽  
Waste Form ◽  
Thin Wall ◽  
Platinum Single Crystal ◽  
In Situ Neutron Diffraction

AbstractA glass-ceramic borosilicate waste form is being considered for immobilization of waste streams of alkali, alkaline-earth, lanthanide, and transition metals generated by transuranic extraction for reprocessing used nuclear fuel. Waste forms are created by partial crystallization on cooling, primarily of oxyapatite and powellite phases. In-situ neutron diffraction experiments were performed to obtain detailed information about crystallization upon cooling from 1200°C. The combination of high temperatures and reactivity of borosilicate glass with typical containers used in neutron experiments, such as vanadium and niobium, prevented their use here. Therefore, methods using sealed thick-walled silica ampoules were developed for the in-situ studies. Unexpectedly, high neutron absorption, low crystal fraction, and high silica container background made quantification difficult for these high temperature measurements. As a follow-up, proof-of-concept measurements were performed on different potential high-temperature container materials, emphasizing crystalline materials so that residual glass in the waste form sample could be more easily analyzed. Room temperature measurements were conducted with a pre-crystallized sample in ‘ideal’ containers stable at low temperatures (i.e., vanadium and thin-wall silica capillaries) and compared to the same measurements in containers stable at high temperatures (i.e, platinum, single crystal sapphire, and thick-walled silica ampoules). Results suggested that Pt is probably the best choice if suitably sealed to prevent contamination from the sample after neutron activation.

Synthesis of the in situ aluminum matrix composite through pyrolysis of high temperature vulcanization silicone

2017 ◽  
Vol 52 (1) ◽  
pp. 123-134 ◽  
Author(s):  
Mohammad Senemar ◽  
Behzad Niroumand ◽  
Ali Maleki ◽  
Pradeep K Rohatgi
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Pure Aluminum ◽  
Aluminum Matrix ◽  
Aluminum Matrix Composite ◽  
Aluminum Matrix Composites ◽  
Matrix Composites ◽  
Commercially Pure ◽  
The Matrix

In this study, in situ aluminum matrix composites were synthesized through pyrolysis of high temperature vulcanization silicone in commercially pure aluminum melt. For this purpose, 1 to 4 wt% of high temperature vulcanization silicone was added to a vortex of molten aluminum at 750℃ and the resulting slurries were cast in steel dies. Microstructure, hardness, and tensile properties of the as-cast samples were examined at ambient and high temperatures. The results revealed the in situ formation and distribution of reinforcement particles in the matrix. Energy-dispersive X-ray analysis indicated that the formed reinforcement particles consisted of O and Si elements. This confirms the in situ reinforcement formation by pyrolysis of high temperature vulcanization silicone in the melt. The size of the in situ formed particles was mostly in the range of 200–2000 nm. It was shown that the composites synthesized by the addition of 4 wt% high temperature vulcanization had the highest mechanical properties both at ambient and high temperatures. Room temperature hardness, tensile strength, and yield strength of this sample were increased by about 50%, 23%, and 19% compared to the monolithic sample, respectively.

In Situ Study of Zirconia Stabilization by Anion Exchange (N for O) Using High-Temperature, Controlled Atmosphere Electron Diffraction

1999 ◽  
Vol 589 ◽  
Author(s):  
Renu Sharma ◽  
Eberhard Schweda ◽  
Dirk Naedele
Keyword(s):  
High Temperature ◽  
Electron Diffraction ◽  
Anion Exchange ◽  
High Temperatures ◽  
Controlled Atmosphere ◽  
In Situ Study ◽  
Environmental Cell ◽  
Temperature Controlled ◽  
Cubic Structure

AbstractStabilization of zirconia by anion exchange (N for O) is a novel idea. A number of oxy-nitrides with flourite-related (cubic) structure have been reported to form at high temperatures (1100°C). We have used a TEM equipped with environmental cell and Gatan Imaging Filter (GIF) to study the nitridation behavior of zirconia. The in situ observations reveal the formation of a cubic structure at ≈800°C when the Zr(OH) 4×H2O precursor was heated in ≈2 torr of NH3. The presence of N in the lattice is confirmed by electron energyloss spectroscopy.

In-situ Hrem Heating Experiments at Very High Temperatures

1995 ◽  
Vol 404 ◽  
Author(s):  
T. Kamino ◽  
H. Saka
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Atomic Resolution ◽  
Very High

AbstractA specimen-heating holder which allows an observation of reactions of more than one materials, in a controlled manner, at such a high temperature as 1723K has been developed. Facet-unfacet transformation and reconstruction of Au-deposited Si surfaces have been observed at very high temperatures at near-atomic resolution.

scholarly journals In Situ Hyperspectral Raman Imaging of Ternesite Formation and Decomposition at High Temperatures

Minerals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 287 ◽  
Author(s):  
Nadine Böhme ◽  
Kerstin Hauke ◽  
Manuela Neuroth ◽  
Thorsten Geisler
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Temperature Stability ◽  
Dicalcium Silicate ◽  
Raman Imaging ◽  
Cement Industry ◽  
Solid State Reactions ◽  
High Temperature Stability ◽  
The One

Knowledge of the high-temperature properties of ternesite (Ca5(SiO4)2SO4) is becoming increasingly interesting for industry in different ways. On the one hand, the high-temperature product has recently been observed to have cementitious properties. Therefore, its formation and hydration characteristics have become an important field of research in the cement industry. On the other hand, it forms as sinter deposits in industrial kilns, where it can create serious problems during kiln operation. Here, we present two highlights of in situ Raman spectroscopic experiments that were designed to study the high-temperature stability of ternesite. First, the spectra of a natural ternesite crystal were recorded from 25 to 1230 °C, which revealed a phase transformation of ternesite to the high-temperature polymorph of dicalcium silicate (α’L-Ca2SiO4), while the sulfur is degassed. With a heating rate of 10 °C/h, the transformation started at about 730 °C and was completed at 1120 °C. Using in situ hyperspectral Raman imaging with a micrometer-scale spatial resolution, we were able to monitor the solid-state reactions and, in particular, the formation properties of ternesite in the model system CaO-SiO2-CaSO4. In these multi-phase experiments, ternesite was found to be stable between 930 to 1020–1100 °C. Both ternesite and α’L-Ca2SiO4 were found to co-exist at high temperatures. Furthermore, the results of the experiments indicate that whether or not ternesite or dicalcium silicate crystallizes during quenching to room temperature depends on the reaction progress and possibly on the gas fugacity and composition in the furnace.

In situ high temperature X-ray diffraction, transmission electron microscopy and theoretical modeling for the formation of WO3 crystallites

CrystEngComm ◽  
2015 ◽  
Vol 17 (36) ◽  
pp. 6985-6998 ◽  
Author(s):  
Suman Pokhrel ◽  
Johannes Birkenstock ◽  
Arezoo Dianat ◽  
Janina Zimmermann ◽  
Marco Schowalter ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
High Temperatures ◽  
Structural Transformation ◽  
Theoretical Modeling ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron

The structural transformation of WO3 at high temperatures.

ESEM as a Tool for Studying High Temperature Electronics

2011 ◽  
Vol 2011 (HITEN) ◽  
pp. 000180-000187
Author(s):  
Stefan Svensson ◽  
Fredric Ericson ◽  
Klas Hjort ◽  
Lena Klintberg
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
High Vacuum ◽  
Surface Charges ◽  
Die Attach ◽  
Sample Chamber ◽  
Differential Pumping ◽  
Electrical Components ◽  
Scanning Electron

Researchers studying materials and processes at high temperatures are often restricted to do evaluation afterwards and at room temperature using e.g. scanning electron microscopy (SEM). Limited by high vacuum, outgassing and non-conducting samples are difficult to study with SEM. For such samples, environmental scanning electron microscope (ESEM) is an alternative that is particularly suited also for high temperature in-situ studies. The electron detector in the ESEM make use of otherwise unwanted scattering of electrons as an amplifier of the signal, and by using differential pumping, it is possible to introduce several mbar of either oxygen, water vapor, or a gas of choice into the sample chamber while still maintaining the high-vacuum in the electron column. The auxiliary gas neutralizes surface charges built up by the electron beam, which makes it possible to image non-conductive and outgassing samples, thus making it possible to study e.g. polymeric and high temperature materials. Our ESEM, FEI XL30, have a heating stage making it possible to reach temperatures up to 1500°C. Equipped with electrical feed-throughs, the instrument can be used to study high temperature phenomena on electrically activated components. ESEM is an instrument that has found its use for biological and organic samples. However, less work has been done using it for high temperature processes. Here, we show real-time imaging of the sintering of dielectric and Ag thick-film prints on AlN substrates. The use of the electrical feed-throughs to activate electrical components and study them at high temperatures is also demonstrated. ESEM is a versatile tool for high temperature studies and in-situ analysis of electrical components, solder processes and different die-attach materials.

Deformation Mechanisms of Aluminum at High Temperatures: in situ Straining Experiments in H.V.E.M.

1975 ◽  
Vol 33 ◽  
pp. 56-57
Author(s):  
D. Caillard ◽  
P. Muchin ◽  
J. L. Martin
Keyword(s):  
High Temperature ◽  
Dislocation Density ◽  
Single Crystals ◽  
High Temperatures ◽  
Room Temperature ◽  
Dislocation Climb ◽  
Deformation Mechanisms ◽  
High Angle ◽  
The One

Aluminium single crystals have been deformed on a straining holder between room temperature and 550° C in a H.V.E.M. Observations are recorded on still photographs or movies.Evidence is shown of crosslip and dislocation climb.1) The formation of dislocation subboundaries has been observed at high temperature and low stresses. The increase with time of dislocation density of each boundary is explained and the coalescence of low angle subboundaries into high angle ones, is described on the basis of our observations by a model involving dislocation climb, different from the one proposed formerly by Dunn and Hibbard.

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