Solid krypton in MgO

1992 ◽  
Vol 7 (12) ◽  
pp. 3171-3174 ◽  
Author(s):  
M. Grant Norton ◽  
C. Barry Carter ◽  
Elizabeth L. Fleischer ◽  
James W. Mayer
Keyword(s):  
High Pressure ◽  
Electron Diffraction ◽  
Ion Implantation ◽  
Single Crystal ◽  
Magnesium Oxide ◽  
Room Temperature ◽  
Noble Gas ◽  
Lattice Parameter ◽  
Solid Krypton ◽  
Measured Lattice Parameter

Recent work by the authors has been extended to demonstrate the formation of solid krypton in single-crystal magnesium oxide. The solid inclusions, which were formed by ion implantation at room temperature, have been identified by electron diffraction. The formation of solid noble gas inclusions at room temperature indicates that they were under a high pressure. This pressure was determined, based on the measured lattice parameter, to be 1.7 GPa.

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2020 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.50 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

High-Temperature Fatigue Properties of Single Crystal Superalloys in Air and Hydrogen

2001 ◽  
Author(s):  
Nagaraj K. Arakere
Keyword(s):  
High Pressure ◽  
Shear Stress ◽  
High Temperature ◽  
Fatigue Life ◽  
Single Crystal ◽  
Room Temperature ◽  
Turbine Blades ◽  
The Core ◽  
Blade Tip ◽  
Pressure Hydrogen

Hot section components in high performance aircraft and rocket engines are increasingly being made of single crystal nickel superalloys such as PWA1480, PWA1484, CMSX-4 and Rene N-4 as these materials provide superior creep, stress rupture, melt resistance and thermomechanical fatigue capabilities over their polycrystalline counterparts. Fatigue failures in PWA1480 single crystal nickel-base superalloy turbine blades used in the Space Shuttle Main Engine (SSME) fuel turbopump are discussed. During testing many turbine blades experienced Stage II non-crystallographic fatigue cracks with multiple origins at the core leading edge radius and extending down the airfoil span along the core surface. The longer cracks transitioned from stage II fatigue to crystallographic stage I fatigue propagation, on octahedral planes. An investigation of crack depths on the population of blades as a function of secondary crystallographic orientation (β) revealed that for β = 45+/- 15 degrees tip cracks arrested after some growth or did not initiate at all. Finite element analysis of stress response at the blade tip, as a function of primary and secondary crystal orientation, revealed that there are preferential β orientations for which crack growth is minimized at the blade tip. To assess blade fatigue life and durability extensive testing of uniaxial single crystal specimens with different orientations has been tested over a wide temperature range in air and hydrogen. A detailed analysis of the experimentally determined Low Cycle Fatigue (LCF) properties for PWA1480 and SC 7-14-6 single crystal materials as a function of specimen crystallographic orientation is presented at high temperature (75 F – 1800 F) in high-pressure hydrogen and air. Fatigue failure parameters are investigated for LCF data of single crystal material based on the shear stress amplitudes on the 24 octahedral and 6 cube slip systems for FCC single crystals. The max shear stress amplitude [Δτmax] on the slip planes reduces the scatter in the LCF data and is found to be a good fatigue damage parameter, especially at elevated temperatures. The parameter Δτmax did not characterize the room temperature LCF data in high-pressure hydrogen well because of the noncrystallographic eutectic failure mechanism activated by hydrogen at room temperature. Fatigue life equations are developed for various temperature ranges and environmental conditions based on power-law curve fits of the failure parameter with LCF test data. These curve fits can be used for assessing blade fatigue life.

Formation of Buried Tisi2 Layers in Single Crystal Silicon by Ion Implantion

1987 ◽  
Vol 107 ◽  
Author(s):  
P. Madakson ◽  
G.J. Clark ◽  
F.K. Legoues ◽  
F.M. d'Heurle ◽  
J.E.E. Baglin
Keyword(s):  
Ion Implantation ◽  
Single Crystal ◽  
Room Temperature ◽  
Single Crystal Silicon ◽  
Crystal Silicon ◽  
Buried Layers

Buried TiSi2 layers, about 600Å thick and 900Å below the surface, were formed in < 111> silicon by ion implantation. The implantation was done with either 120 or 170 keV Ti+ to doses ranging from 5 x 1016 to 2 x 1017 ions/cm2, and at temperatures of between ambient and 650° C. Annealing was done at 600° C, 700°C and 1000°C. Continuous buried layers were achieved only with samples implanted with doses equal or greater than 1017 ions/cm2 and at temperatures above 450°C. Below this dose TiSi2, was present only as discrete precipitates. For room temperature implants, the TiSi2, layer is formed on the surface. The damage present consists of dispersed TiSi6 precipitates and microtwins.

Design of 2D-nanocrystals in water: preparation, structure and functionalization

2018 ◽  
Vol 90 (5) ◽  
pp. 833-844
Author(s):  
Leonid Aslanov ◽  
Valery Zakharov ◽  
Ksenia Paseshnichenko ◽  
Aleksandr Yatsenko ◽  
Andrey Orekhov ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Chemical Composition ◽  
High Resolution ◽  
Electron Diffraction ◽  
Single Crystal ◽  
Room Temperature ◽  
Energy Dispersive ◽  
X Ray ◽  
Transmission Electron

AbstractA new method for synthesis of 2D nanocrystals in water was proposed. The use of perfluorothiophenolate ions as surfactant allowed us to produce 2D single-crystal nanosheets of CaS at pH=9 and flat nanocrystals of PbS at pH=9 at room temperature. Mesocrystalline nanobelts of CdS and mesocrystals of PbS were obtained at pH=3–5 and pH=10–12, respectively. Morphology, structure and chemical composition of nanoparticles were characterized by high-resolution transmission electron microscopy, electron diffraction and energy dispersive X-ray spectroscopy. A mechanism of nanoparticles formation was discussed.

Elasticity of single-crystal low water content hydrous pyrope at high-pressure and high-temperature conditions

2019 ◽  
Vol 104 (7) ◽  
pp. 1022-1031 ◽  
Author(s):  
Dawei Fan ◽  
Jingui Xu ◽  
Chang Lu ◽  
Sergey N. Tkachev ◽  
Bo Li ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Single Crystal ◽  
Upper Mantle ◽  
Room Temperature ◽  
Seismic Anisotropy ◽  
Ambient Pressure ◽  
Seismic Velocities ◽  
Shear Moduli ◽  
Derivatives Of

Abstract The elasticity of single-crystal hydrous pyrope with ~900 ppmw H2O has been derived from sound velocity and density measurements using in situ Brillouin light spectroscopy (BLS) and synchrotron X-ray diffraction (XRD) in the diamond-anvil cell (DAC) up to 18.6 GPa at room temperature and up to 700 K at ambient pressure. These experimental results are used to evaluate the effect of hydration on the single-crystal elasticity of pyrope at high pressure and high temperature (P-T) conditions to better understand its velocity profiles and anisotropies in the upper mantle. Analysis of the results shows that all of the elastic moduli increase almost linearly with increasing pressure at room temperature, and decrease linearly with increasing temperature at ambient pressure. At ambient conditions, the aggregate adiabatic bulk and shear moduli (KS0, G0) are 168.6(4) and 92.0(3) GPa, respectively. Compared to anhydrous pyrope, the presence of ~900 ppmw H2O in pyrope does not significantly affect its KS0 and G0 within their uncertainties. Using the third-order Eulerian finite-strain equation to model the elasticity data, the pressure derivatives of the bulk [(∂KS/∂P)T] and shear moduli [(∂G/∂P)T] at 300 K are derived as 4.6(1) and 1.3(1), respectively. Compared to previous BLS results of anhydrous pyrope, an addition of ~900 ppmw H2O in pyrope slightly increases the (∂KS/∂P)T, but has a negligible effect on the (∂G/∂P)T within their uncertainties. The temperature derivatives of the bulk and shear moduli at ambient pressure are (∂KS/∂T)P = –0.015(1) GPa/K and (∂G/∂T)P = –0.008(1) GPa/K, which are similar to those of anhydrous pyrope in previous BLS studies within their uncertainties. Meanwhile, our results also indicate that hydrous pyrope remains almost elastically isotropic at relevant high P-T conditions, and may have no significant contribution to seismic anisotropy in the upper mantle. In addition, we evaluated the seismic velocities (νP and νS) and the νP/νS ratio of hydrous pyrope along the upper mantle geotherm and a cold subducted slabs geotherm. It displays that hydrogen also has no significant effect on the seismic velocities and the νP/νS ratio of pyrope at the upper mantle conditions.

Nanosized Thallium Inclusions in Aluminium

1993 ◽  
Vol 316 ◽  
Author(s):  
E. Johnson ◽  
A. Johansen ◽  
K.K. Bourdelle ◽  
H.H. Andersen ◽  
L. Sarholt-Kristensen
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Orientation Relationship ◽  
Room Temperature ◽  
Equilibrium Phase ◽  
Lattice Parameter ◽  
Metastable Equilibrium ◽  
Stable Phase ◽  
Pure Aluminium ◽  
Temperature Equilibrium

ABSTRACTIon implantation of pure aluminium with thallium induces formation of nanosized crystalline thallium inclusions with either fee or bee structure. The size of the inclusions depends on the implantation conditions and subsequent annealing treatments. Inclusions less than 10-15 nm in size are generally fee while larger inclusions are bee. The fee inclusions are aligned topotactically with the aluminium matrix with a cube/cube orientation relationship, and they have a truncated octahedral shape bounded by {111} and {001} planes. The lattice parameter of the fee thallium inclusions is 0.484 nm ± 0.002 nm, which is slightly but significantly larger than for the high pressure fee thallium phase known to be stable above 3.8 GPa. The lattice parameter of the bec inclusions is close to the equilibrium value of 0.387 nm and the orientation relationship is given by the Kurdjumov-Sachs rule (011)bcc ║ (111)fcc and [111]bcc ║ [101]fcc The bec inclusions,, representing the high temperature equilibrium phase but existing in metastable equilibrium at lower temperatures, have curved and less well-defined facets. Inclusions with hep structure, the stable phase at room temperature, have not been observed.

High-pressure syntheses and crystal structures of orthorhombic DyGaO3 and trigonal GaBO3

2015 ◽  
Vol 70 (4) ◽  
pp. 207-214 ◽  
Author(s):  
Daniela Vitzthum ◽  
Stefanie A. Hering ◽  
Lukas Perfler ◽  
Hubert Huppertz
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Single Crystal ◽  
Crystal Structures ◽  
Diffraction Data ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Space Group ◽  
X Ray ◽  
High Pressure High Temperature

AbstractOrthorhombic dysprosium orthogallate DyGaO3 and trigonal gallium orthoborate GaBO3 were synthesized in a Walker-type multianvil apparatus under high-pressure/high-temperature conditions of 8.5 GPa/1350 °C and 8 GPa/700 °C, respectively. Both crystal structures could be determined by single-crystal X-ray diffraction data collected at room temperature. The orthorhombic dysprosium orthogallate crystallizes in the space group Pnma (Z = 4) with the parameters a = 552.6(2), b = 754.5(2), c = 527.7(2) pm, V = 0.22002(8) nm3, R1 = 0.0309, and wR2 = 0.0662 (all data) and the trigonal compound GaBO3 in the space group R3̅c (Z = 6) with the parameters a = 457.10(6), c = 1419.2(3) pm, V = 0.25681(7) nm3, R1 = 0.0147, and wR2 = 0.0356 (all data).

Single Crystal Growth of High-Pressure Phases of Ice and Salt Hydrate Far Below the Original Melting Point by Mixing Alcohol: Crystal Structure Determination of Magnesium Chloride Heptahydrate

2019 ◽  
Author(s):  
Keishiro Yamashita ◽  
Kazuki Komatsu ◽  
Hiroyuki Kagi
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Crystal Growth ◽  
Single Crystal ◽  
Room Temperature ◽  
Growth Technique ◽  
Salt Hydrate ◽  
X Ray

An crystal-growth technique for single crystal x-ray structure analysis of high-pressure forms of hydrogen-bonded crystals is proposed. We used alcohol mixture (methanol: ethanol = 4:1 in volumetric ratio), which is a widely used pressure transmitting medium, inhibiting the nucleation and growth of unwanted crystals. In this paper, two kinds of single crystals which have not been obtained using a conventional experimental technique were obtained using this technique: ice VI at 1.99 GPa and MgCl<sub>2</sub>·7H<sub>2</sub>O at 2.51 GPa at room temperature. Here we first report the crystal structure of MgCl2·7H2O. This technique simultaneously meets the requirement of hydrostaticity for high-pressure experiments and has feasibility for further in-situ measurements.

scholarly journals High-pressure, high-temperature molecular doping of nanodiamond

2019 ◽  
Vol 5 (5) ◽  
pp. eaau6073 ◽  
Author(s):  
M. J. Crane ◽  
A. Petrone ◽  
R. A. Beck ◽  
M. B. Lim ◽  
X. Zhou ◽  
...  
Keyword(s):  
High Pressure ◽  
Ion Implantation ◽  
High Pressures ◽  
Noble Gas ◽  
Color Centers ◽  
Vacancy Defects ◽  
High Pressure High Temperature ◽  
Pressure Medium ◽  
Optical Pressure ◽  
Pressure Metrology

The development of color centers in diamond as the basis for emerging quantum technologies has been limited by the need for ion implantation to create the appropriate defects. We present a versatile method to dope diamond without ion implantation by synthesis of a doped amorphous carbon precursor and transformation at high temperatures and high pressures. To explore this bottom-up method for color center generation, we rationally create silicon vacancy defects in nanodiamond and investigate them for optical pressure metrology. In addition, we show that this process can generate noble gas defects within diamond from the typically inactive argon pressure medium, which may explain the hysteresis effects observed in other high-pressure experiments and the presence of noble gases in some meteoritic nanodiamonds. Our results illustrate a general method to produce color centers in diamond and may enable the controlled generation of designer defects.

Cryo-Implantation Technology for Controlling Defects and impurity out diffusion

2000 ◽  
Vol 610 ◽  
Author(s):  
Atsushi Murakoshi ◽  
Kyoichi Suguro ◽  
Masao Iwase ◽  
Mitsuhiro Tomita ◽  
Katsuya Okumura
Keyword(s):  
Ion Implantation ◽  
Substrate Temperature ◽  
Single Crystal ◽  
Room Temperature ◽  
Amorphous Layer ◽  
Junction Depth ◽  
Si Substrate ◽  
Enhanced Diffusion ◽  
Pn Junction ◽  
Order Of Magnitude

AbstractWe propose a novel process module by using cryo-implantation and rapid thermal annealing (RTA). Boron or arsenic ions were implanted into a 8 inch (100) Si substrate which was cooled by using liquid nitrogen. The substrate temperature was controlled to be below at -160°C during ion implantation. It was found that an amorphous layer was formed by boron or arsenic implantation and the amorphous layer was completely recovered to a single crystal after annealing at 900°C for 30sec. No dislocation was observed in the implanted layer. It was also found that the thermal diffusion of boron was suppressed by cryo-implantation. PN junction depth was found to be about 10-20% shallower than that of room temperature implantation. These results suggest that transient enhanced diffusion of boron can be reduced by suppressing vacancy migration toward the surface during implantation. Cryo-implantation was found to be very effective in reducing defects and PN junction leakage was successfully reduced by one order of magnitude as compared with room temperature implantation.

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