New 1212-Molybdo-Cuprate phases using High pressure and high temperature synthesis

MRS Advances ◽  
2016 ◽  
Vol 1 (17) ◽  
pp. 1215-1225
Author(s):  
Sourav Marik ◽  
A. J. Dos santos-Garcia ◽  
Emilio Morán ◽  
O. Toulemonde ◽  
M. A. Alario-Franco
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Electron Diffraction ◽  
Photoelectron Spectroscopy ◽  
Tetragonal Symmetry ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
Oxidation State Of Copper ◽  
Diagonal Cell

ABSTRACTNew 1212- type Molybdo-Cuprates of with composition Mo0.5Cu0.5Sr2RECu2O7.5 (RE = Rare Earth) have been prepared by High Pressure and High Temperature (HPHT) synthesis. Their crystal structures are characterized by combining the X-Ray/Neutron powder diffraction and electron diffraction techniques. All the materials show tetragonal symmetry, crystallizing in the P4/mmm space group (S.G.). The chain oxygens are randomly distributed in the two different oxygen sites, which are not completely filled and the defect induced by oxygen vacancies in fact makes the chain fragmented and disordered. The microstructure of these compounds is interpreted by a well-known diagonal cell √2ap × √2ap × 3ap, as confirmed by the Electron diffraction (ED) and transmission electron microscope (TEM). X-ray photoelectron spectroscopy (XPS) studies show the predominance of the non magnetic MoVI state over the MoV one. At the same time oxidation state of copper is found to be dominated by CuII.

Investigation on B, Cr Doped Ni3Al Alloy Prepared by Self-Propagation High-Temperature Synthesis and Hot Extrusion

2013 ◽  
Vol 747-748 ◽  
pp. 124-131 ◽  
Author(s):  
Li Yuan Sheng ◽  
Jian Ting Guo ◽  
Chao Yuan ◽  
F. Yang ◽  
G.S. Li ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Mechanical Properties ◽  
High Temperature ◽  
Hot Extrusion ◽  
The Self ◽  
Al Alloy ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Transmission Electron

The Ni3Al and Ni3Al-B-Cr alloys were fabricated by the self-propagation high-temperature synthesis with hot extrusion method. Their microstructure and mechanical properties were studied by using combination of X-ray diffraction, optical microscopy, transmission electron microscopy and compression test. Analysis of X-ray spectra exhibited that the elemental powders had been transformed to the Ni3Al phase after the self-propagation high-temperature synthesis processing. Microstructure examination showed that the alloy without extrusion consisted of coarse and fine grains, but the subsequent hot extrusion procedure homogenized the grain size and densified the alloy obviously. Transmission electron microscopy observations on the Ni3Al alloy revealed that Ni3Al, γ-Ni and Al2O3 particles were the main phases. When the boron and chromium were added, besides the β-NiAl phase, α-Cr phase and some Cr7Ni3 particles with stacking faults inside were observed. In addition, a lot of substructure and high-density dislocation arrays were observed in the extruded part, which indicated that the subsequent extrusion had led to great deformation and partly recrystallizing in the alloy. Moreover, the subsequent extrusion procedure redistributed the Al2O3 particles and eliminated the γ-Ni. These changes were helpful to refine the microstructure and weaken the misorientation. The mechanical test showed that the self-propagation high-temperature synthesis with hot extrusion improved the mechanical properties of the Ni3Al alloy significantly. The addition of B and Cr in Ni3Al alloy increased the mechanical properties further, but the compressive strength of the alloy was still lower than that synthesized by combustion. Finally, the self-propagation high-temperature synthesis with hot extrusion was a good method to prepare Ni3Al alloy from powder.

Effect of NaCl on Synthesis of Si-SiC Nanocomposites by Self Propagating High Temperature Synthesis

2013 ◽  
Vol 664 ◽  
pp. 449-453 ◽  
Author(s):  
Sutham Niyomwas
Keyword(s):  
Electron Microscopy ◽  
High Temperature ◽  
X Ray Diffraction ◽  
Temperature Synthesis ◽  
Nano Composite ◽  
Argon Gas ◽  
X Ray ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
Scanning Electron

The Si-SiC nanocomposites have been synthesized by self-propagating high temperature synthesis (SHS) from natural precursors. The effects of difference amount of added NaCl from 0 to 0.75 moles to the reactants on the Si-SiC conversion and particle size were investigated. The reaction were carried out in a SHS reactor under static argon gas at the pressure of 0.5 MPa. The nanocomposite results have been characterized by scanning electron microscope, Transmission Electron Microscopy and X-ray diffraction. The results showed that the production of nano-composite materials using SHS process is feasible and agree well with the thermodynamics calculations.

scholarly journals Single-Crystal Structure of HP-Sc2TeO6 Prepared by High-Pressure/High-Temperature Synthesis

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1554
Author(s):  
Raimund Ziegler ◽  
Martina Tribus ◽  
Clivia Hejny ◽  
Gunter Heymann
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Single Crystal ◽  
Ambient Pressure ◽  
Normal Pressure ◽  
Monoclinic Space Group ◽  
Temperature Synthesis ◽  
X Ray ◽  
High Temperature Synthesis ◽  
High Pressure High Temperature

The first high-pressure scandium tellurate HP-Sc2TeO6 was synthesized from an NP-Sc2TeO6 normal-pressure precursor at 12 GPa and 1173 K using a multianvil apparatus (1000 t press, Walker-type module). The compound crystallizes in the monoclinic space group P2/c (no. 13) with a = 729.43(3), b = 512.52(2), c = 1095.02(4) pm and β = 103.88(1)°. The structure was refined from X-ray single-crystal diffractometer data: R1 = 0.0261, wR2 = 0.0344, 568 F2 values and 84 variables. HP-Sc2TeO6 is isostructural to Yb2WO6 and is built up from TeO6 octahedra, typical for tellurate(VI) compounds. During synthesis, a reconstructive transition from P321 (normal-pressure modification) to P2/c (high-pressure modification) takes place and the scandium–oxygen distances as well as the coordination number of scandium increase. However, the coordination sphere around the Te6+ cations gets only slightly distorted. High-temperature powder XRD investigations revealed a back-transformation of HP-Sc2TeO6 to the ambient-pressure modification above 973 K.

Behavior of carbon nanotubes under high pressure and high temperature

2000 ◽  
Vol 15 (2) ◽  
pp. 560-563 ◽  
Author(s):  
D. S. Tang ◽  
L. C. Chen ◽  
L. J. Wang ◽  
L. F. Sun ◽  
Z. Q. Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Carbon Nanotubes ◽  
High Pressure ◽  
High Temperature ◽  
Structural Changes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Diamond Crystallization ◽  
Graphite Sheets

The structural changes of carbon nanotubes induced by high pressure and high temperature were investigated by means of x-ray diffraction, Raman scattering, scanning electron microscopy, and transmission electron microscopy. It is shown that, with increasing pressure and temperature, the lattice constant d002 of tubes shortens, and then tubes collapse into tapelike ones; at the same time the C–C bonds at high curvature break, which lead the tapelike tubes to break into graphite sheets as diamond crystallization centers. Compared with graphite, the diamond particles from carbon nanotubes have many defects as the trace of tubes.

scholarly journals High-pressure synthesis of SmGe3

2020 ◽  
Vol 235 (8-9) ◽  
pp. 333-339
Author(s):  
Julia-Maria Hübner ◽  
Wilder Carrillo-Cabrera ◽  
Raul Cardoso-Gil ◽  
Primož Koželj ◽  
Ulrich Burkhardt ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
High Pressure ◽  
Temperature Synthesis ◽  
X Ray ◽  
Selected Area Electron Diffraction ◽  
Unknown Phase ◽  
High Temperature Synthesis ◽  
Transmission Electron ◽  
High Pressure High Temperature ◽  
Pressure Synthesis

AbstractThe new samarium germanide SmGe3 is obtained by high-pressure high-temperature synthesis of pre-reacted mixtures of samarium and germanium at a pressure of 9.5 GPa and temperatures between 1073 and 1273 K. SmGe3 decomposes at 470(5) K into SmGe2, α-Sm3Ge5 and a hitherto unknown phase. SmGe3 exhibits a superstructure of the cubic Cu3Au-type. Transmission electron microscopy measurements of crystalline particles and prepared lamellae indicate a high density of defects on the nanoscale. Selected area electron diffraction and elaborate X-ray powder diffraction measurements consistently indicate a 2a0 × 2a0 × 2a0 superstructure adopting space group $Fm\overline{3}m$ with a = 8.6719(2) Å.

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