Peritectic Melting Sequence of Bi-2212 and Bi-2212/Ag Measured Using Insitu XRD

1995 ◽  
Vol 39 ◽  
pp. 723-729
Author(s):  
S. T. Misture ◽  
D. P. Mathers ◽  
R. L. Snyder ◽  
T. N. Blanton ◽  
G. M. Zom ◽  
...  
Keyword(s):  
High Temperature ◽  
Thick Films ◽  
Tape Casting ◽  
Lattice Parameter ◽  
Residual Carbon ◽  
Preparation Technique ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sample Preparation Technique ◽  
Peritectic Melting

High temperature X-ray diffraction (HTXRD) was used to determine the peritectic melting sequence of BI2Sr2CaCu2O8 (Bi-2212) and Bi-2212+20 wt.% Ag thick films on MgO substrates. The optimized sample preparation technique includes tape casting the powders to form 10μm thick films, and reducing the residual carbon concentration to 1600 ppm by careful thermal treatment before the HTXRD measurements. Lattice parameter analyses were used to determine the compositions of solid solutions present in the partially-melted state. Pour phases form during melting Bi-2212 or Bi-2212 + Ag, including an unidentified phase, (C0,4Sr0,6CuO2, (Ca1,4Sr0,6)CuO3, and (Sr,Ca)0.

scholarly journals Probing the Dehydroxylation of Kaolinite and Halloysite by In Situ High Temperature X-ray Diffraction

Minerals ◽  
2020 ◽  
Vol 10 (5) ◽  
pp. 480
Author(s):  
Imane Daou ◽  
Gisèle Lecomte-Nana ◽  
Nicolas Tessier-Doyen ◽  
Claire Peyratout ◽  
Maurice Gonon ◽  
...  
Keyword(s):  
High Temperature ◽  
Coefficient Of Thermal Expansion ◽  
Tape Casting ◽  
Treatment Temperature ◽  
Structure Evolution ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pole Figures ◽  
Basal Distance

Textured kaolinite and halloysite-based materials were shaped by tape casting in order to promote the alignment of clay particles along the tape casting direction and to investigate the structure evolution of these phyllosilicates during the dehydroxylation process. The crystallinity indexes HI and R2 of the starting kaolins (KRG and KCS) were determined and appeared close to values found for the well-ordered reference kaolin KGa-1b. The halloysite clay exhibited trimodal grain size distribution and tended to be less textured than KRG and KCS according to the (002) pole figures performed on green tapes. The constant heating rate derived kinetic parameters matched the expected range. We followed the dehydroxylation of kaolinite and halloysite through in situ high-temperature X-ray diffraction measurements at the ESRF synchrotron radiation source on the D2AM beamline. The dehydroxylation of these kaolinite and halloysite occurred between 425 °C and 675 °C for KRG and KCS and from 500 °C to 650 °C for halloysite. In addition, the evolution of the basal distance of kaolinite regarding the heat treatment temperature confirmed that the dehydroxylation process occurred in three steps: delamination, dehydroxylation, and formation of metakaolinite. The calculated coefficient of thermal expansion (CTE) along the c axe values were close to 17 × 10−6 °C−1 for kaolinite (KCS and KRG) and 14 × 10−6 °C−1 for halloysite.

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 analysis of chemical expansion and stability of SOFC cathodes

2014 ◽  
Vol 1655 ◽  
Author(s):  
Mirela Dragan ◽  
Scott Misture
Keyword(s):  
High Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Lattice Parameter ◽  
Low Oxygen ◽  
X Ray Diffraction ◽  
Chemical Expansion ◽  
X Ray ◽  
Reducing Conditions ◽  
The Stability

ABSTRACTIn this work high-temperature X-ray diffraction has been used to investigate thermal and chemical expansion as well as overall phase stability for various cathode materials: Ba0.5Sr0.5Co0.8Fe0.2O3 (BSCF), La0.3Sr0.7CoO3 (LSC37), La0.6Sr0.4CoO3 (LSC64) and La0.6Sr0.4Fe0.8Co0.2O3 (LSCF), as a function of temperature in reducing conditions. When perovskites materials are under a low oxygen partial-pressure condition, the lattice parameter and overall dimension increase. Their chemical expansion has comparable values. From the viewpoint of the stability of these phases, the high-temperature X-ray diffraction results indicate no phase decomposition can be one of the reasons for material failure at the current experimental oxygen partial pressure. LSF is most stable, while LSC and LSCF form oxygen vacancy-ordered phases and then decompose when heated to 1000°C under atmospheres with pO2 as low as 10-5 atm.

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.

Determination of Thermal Expansion by High-Temperature X-Ray Diffraction

1961 ◽  
Vol 5 ◽  
pp. 238-243 ◽  
Author(s):  
Dale A. Vaughan ◽  
Charles M. Schwartz
Keyword(s):  
Thermal Expansion ◽  
High Temperature ◽  
Ceramic Materials ◽  
Lattice Parameter ◽  
Specimen Preparation ◽  
X Ray Diffraction ◽  
X Ray ◽  
And Control ◽  
Measurement And Control

AbstractTwo high-temperature X-ray diffraction cameras are described which have been employed at Battelle to determine thermal expansion of metals and ceramic materials. Specimen preparation and temperature measurement and control are described. Lattice-parameter data vs. temperature are presented for uranium, uranium dioxide, and magnesium oxide.

Étude du système U-Sr-O par diffraction X à haute température

1999 ◽  
Vol 77 (8) ◽  
pp. 1384-1393 ◽  
Author(s):  
André Pialoux ◽  
Bernard Touzelin
Keyword(s):  
High Temperature ◽  
Lattice Parameter ◽  
Reduced Form ◽  
X Ray Diffraction ◽  
Constant Composition ◽  
X Ray ◽  
Lattice Constants ◽  
Metallic Oxides ◽  
Composition Variation ◽  
Fluorite Type

High-temperature X-ray diffraction (293 [Formula: see text] T(K) [Formula: see text] 1773) is used to investigate the reaction between strontium monoxide and uranium dioxide under controlled atmosphere (105 [Formula: see text] [Formula: see text] (Pa) [Formula: see text] 10-24), with lattice parameter measurements and composition estimates of the different uranates obtained. Thus, with a Sr/U = 1 sample, we successively observe the phases: (a) orthorhombic α-"SrUO4", whose reduction (3.67 [Formula: see text] O/U [Formula: see text] 3.62) is shown by a constant volume of the cell (V = 0.367 nm3) between 1173 et 1373 K; (b) rhombohedral β-"SrUO4", which shows a large composition variation between the metastable oxidized form (β-SrUO3.60) below 1108 K and the stable conjugate reduced form (β'-SrUO3.11) at whatever temperature; (c) "SrUO3" of constant composition (O/U [Formula: see text] 3) between 293 and 1533 K, then variable (O/U < 3) above 1533 K, with a probable second-order transformation (α-Pnma, β-Imma) for this distorted perovskite near 1073 K; (d) fluorite type U1-δSrδO2-δ solid solution for which a maximal account in SrO (δ [Formula: see text] 0.25) induces a 0.5 % thermal expansion parameter in comparison with UO2.00. A pseudo-binary "SrUO3"-"SrUO4" phase diagram is propounded. With a sample compound of Sr/U = 3, the monoclinic "Sr3UO6" perovskite is stable under [Formula: see text] [Formula: see text] 105 Pa up to 1373 K. On the other hand, in reducing atmosphere ([Formula: see text] [Formula: see text] 10-19 Pa), it becomes orthorhombic "Sr3UO5" with much greater lattice constants at every temperature.Key words: high-temperature X-ray diffraction, reactivity in metallic oxides, U-Sr-O system, nuclear fuels.

The Dramatic Effect of Crystallite Size on X-Ray Intensities

1982 ◽  
Vol 26 ◽  
pp. 111-117 ◽  
Author(s):  
James P. Cline ◽  
Robert L. Snyder
Keyword(s):  
Spray Drying ◽  
Energy Minimization ◽  
Primary Source ◽  
Preferred Orientation ◽  
Preparation Technique ◽  
X Ray Diffraction ◽  
Spherical Form ◽  
X Ray ◽  
Sample Preparation Technique ◽  
Spherical Agglomerates

Preferred orientation has long been considered the primary source of systematic error involved in quantitative analysis by X-ray powder diffraction. Techniques of spherical agglomeration have been shown to eliminate preferred orientation provided that the agglomerate size is made sufficiently larger than the particle size. These techniques invariably employ the surface energy minimization of a liquid phase dispersed within a second fluid to create the spherical form desired. Spray drying has been the only method to date which has been successfully used to prepare spherical agglomerates suitable for X-ray diffraction. This study was undertaken to investigate possible deleterious effects of spray drying as a diffraction sample preparation technique.

Search for New Semiconductors for High Temperature Applications:The BaPb1-x BixO3 System

1998 ◽  
Vol 512 ◽  
Author(s):  
V. Ponnambalam ◽  
U. V. Varadaraju
Keyword(s):  
Phase Transition ◽  
High Temperature ◽  
Single Phase ◽  
Random Distribution ◽  
Lattice Parameter ◽  
Cubic Phase ◽  
Linear Variation ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Power Factor

ABSTRACTBaPbl-xBixO3 phases with 0.6⋚ x⋚ 1.0 were synthesized by high temperature solid state reaction. Powder X-ray diffraction measurements show that all compositions are in single phase. Linear variation of lattice parameter is observed in BaPb1-xBixO3 with change in x indicating the random distribution of Pb in Bi sites. The activation energies for conduction of phases with x=0.8−0.6 obtained from ρ −T plots are same suggesting that the band gap does not change for compositions with x-0.8−0.6. The low activation energy obtained for BaBiO3 can be attributed to the structure of the compound. S versus (1000/T) data of x=1.0−0.8 exhibit a two-slope behavior. The orthorhombic to cubic phase transition could be the possible reason for the high power factor values of BaBiO3.

High-temperature x-ray diffraction studies of a precursor mixture for Pb-substituted Bi-2223 superconducting wires

1998 ◽  
Vol 13 (3) ◽  
pp. 574-582 ◽  
Author(s):  
A. R. Drews ◽  
J. P. Cline ◽  
T. A. Vanderah ◽  
K. V. Salazar
Keyword(s):  
High Temperature ◽  
Rapid Heating ◽  
Phase Evolution ◽  
Lattice Parameter ◽  
Superconducting Tapes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Superconducting Wires ◽  
Silver Substrate ◽  
Xrd Patterns

High-temperature x-ray diffraction measurements of a (Bi, Pb)-2223 precursor mixture used to produce high-Jc superconducting tapes were conducted on silver and ZrO2 substrates. The precursor mixture consisted primarily of 2212, Ca2PbO4, and CuO. Phase evolution was markedly sensitive to oxygen partial pressure: In 10% O2 growth of the 2223 phase on silver was rapid, proceeded at the expense of the 2212 phase, and was preceded by the disappearance of the Ca2PbO4 phase. When slowly heated on a silver substrate in 7.5% O2 the 2212 phase melted near 800 °C and subsequently recrystallized near 820 °C in a highly textured form, but with no detectable 2223 formation. Under similar conditions on a ZrO2 substrate, the mixture exhibited no marked changes in the XRD patterns up to 850 °C. The dramatic reactivity on silver was also highly dependent on heating rate; rapid heating in 7.5% O2 to 825 °C did not result in melting of the 2212 phase or appearance of the 2223 phase. In experiments leading to formation of 2223, the c-lattice parameter of the 2212 phase contracted just prior to the onset of formation of 2223. This result is consistent with the formation of an intermediate Pb-doped phase of 2212. A transient amorphous phase appeared briefly at the onset of formation of 2223. No evidence for intergrowth conversion of 2212 to 2223 was observed.

Crystal structure of Ca1−xSrxZr4(PO4)6 (0≤x≤1)

2004 ◽  
Vol 19 (2) ◽  
pp. 153-156 ◽  
Author(s):  
Werner Fischer ◽  
Lorenz Singheiser ◽  
Debabrata Basu ◽  
Amit Dasgupta
Keyword(s):  
Crystal Structure ◽  
Solid Solution ◽  
High Temperature ◽  
Structural Transformation ◽  
Powder Diffraction ◽  
Room Temperature ◽  
Lattice Parameter ◽  
Unit Cell ◽  
X Ray Diffraction ◽  
X Ray

The crystal structure of several compounds of Ca1−xSrxZr4(PO4)6 ceramics has been investigated by X-ray powder diffraction at room temperature. All compounds form a solid solution with a unique unit cell. While the lattice parameter a of the hexagonal unit cell decreases of about 0.9% with increasing Sr content only slightly, it considerably elongates in c direction (2.8%). No structural transformation has been observed by high-temperature X-ray diffraction up to 1000 °C.

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