scholarly journals Single-pass flow-through reaction cell for high-temperature and high-pressurein situneutron diffraction studies of hydrothermal crystallization processes

2012 ◽  
Vol 45 (2) ◽  
pp. 166-173 ◽  
Author(s):  
Fang Xia ◽  
Joël Brugger ◽  
Gujie Qian ◽  
Yung Ngothai ◽  
Brian O'Neill ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Flow Rate ◽  
Room Temperature ◽  
Ambient Pressure ◽  
Vacuum Furnace ◽  
Hydrothermal Crystallization ◽  
Single Pass ◽  
Flow Through

A large-volume single-pass flow-through cell forin situneutron diffraction investigation of hydrothermal crystallization processes is reported. The cell is much more versatile than previous designs owing to the ability to control independently and precisely temperature (up to 673 K), pressure (up to 46 MPa), flow rate (0.01–10 ml min−1) and reaction-fluid volume (≥65 ml). Such versatility is realized by an innovative design consisting of a room-temperature and ambient-pressure external fluid supply module, a high-pressure reaction module which includes a high-temperature sample compartment enclosed in a vacuum furnace, and a room-temperature and high-pressure backpressure regulation module for pressure control. The cell provides a new avenue for studying various parameters of hydrothermal crystallizations independently,in situand in real time at extreme hydrothermal conditions (e.g.supercritical). The cell was successfully commissioned on the high-intensity powder diffractometer beamline, Wombat, at the Australian Nuclear Science and Technology Organisation by investigating the effect of pressure on the hydrothermal pseudomorphic conversion from SrSO4(celestine) to SrCO3(strontianite) at a constant temperature of 473 K and flow rate of 5 ml min−1. The results show that the increase of pressure exerts a nonlinear effect on the conversion rate, which first increases with increasing pressure from 14 to 20 MPa, and then decreases when pressure further increases to 24 MPa.

High-Pressure Synthesis, Crystal Structure, and Properties of the New Orthorhombic Rare-Earth meta-Oxoborates RE(BO2)3 (RE = Dy – Lu)

2004 ◽  
Vol 59 (2) ◽  
pp. 202-215 ◽  
Author(s):  
Holger Emme ◽  
Tanja Nikelski ◽  
Thomas Schleid ◽  
Rainer Pöttgen ◽  
Manfred Heinrich Möller ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Ambient Pressure ◽  
Structure And Properties ◽  
Crystal Data ◽  
Temperature Conditions ◽  
Pressure Synthesis ◽  
Ir Spectroscopic ◽  
Pressure Phase

The new orthorhombic meta-oxoborates RE(BO2)3 (≡REB3O6) (RE = Dy-Lu) have been synthesized under high-pressure and high-temperature conditions in a Walker-type multianvil apparatus at 7.5 GPa and 1100 °C. They are isotypic to the known ambient pressure phase Tb(BO2)3, space group Pnma. In contrast to Dy(BO2)3, which was also obtained in small amounts under high-temperature conditions, the preparation of the higher orthorhombic homologues RE(BO2)3 (RE = Ho-Lu) was only possible using high-pressure. The meta-oxoborates RE(BO2)3 (RE = Dy-Er) were synthesized as pure products, whereas the orthorhombic phases with RE = Tm-Lu were only obtained as byproducts. With the exception of Yb(BO2)3 it was possible to establish single crystal data for all compounds. The results of temperature-resolved in-situ powder-diffraction measurements, DTA, IR-spectroscopic investigations, and magnetic properties are also presented.

Crystal structures and high-temperature vibrational spectra for synthetic boron and aluminum doped hydrous coesite

2020 ◽  
Author(s):  
Yu Ye ◽  
Yunfan Miao ◽  
Joseph R. Smyth ◽  
Junfeng Zhang
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Single Crystals ◽  
Vibrational Spectra ◽  
Fourier Transformation ◽  
Ambient Pressure ◽  
Al Content ◽  
Al Substitution ◽  
Long Time

<p>Coesite, a high-pressure SiO2 polymorph, has drawn extensive interest from the mineralogical community for a long time. In this study, we synthesized hydrous coesite samples with different B and Al concentrations at 5 and 7.5 GPa (1273 K). The B concentration could be more than 400 B/10<sup>6</sup>Si with about 300 ppmw. H2O, while the Al content can be as much as 1200 ~ 1300 Al/10<sup>6</sup>Si with CH2O restrained to be less than 10 ppmw. Hence, B-substitution may prefer the mechanism of Si<sup>4+</sup> = B<sup>3+</sup> + H<sup>+</sup>, whereas Al-substitution could be dominated by 2Si<sup>4+</sup> = 2Al<sup>3+</sup> + O<sub>V</sub>. The doped B<sup>3+</sup> and Al<sup>3+</sup> cations may be concentrated in the Si1 and Si2 tetrahedra, respectively, and make noticeable changes in the Si-O4 and Si-O5 bond lengths. In-situ high-temperature Raman and Fourier Transformation Infrared (FTIR) spectra were collected at ambient pressure. The single crystals of coesite were observed to be stable up to 1500 K. The isobaric Grüneisen parameters (ϒ<sub>i<em>P</em></sub>) of the external modes (< 350 cm<sup>-1</sup>) are systematically smaller in the Al-doped samples, as compared with those for the Al-free ones, while most of the OH-stretching bands shift to higher frequencies in the high temperature range up to ~ 1100 K</p>

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.

Practical and "Unusual" Applications in X-ray Diffraction Using Position Sensitive Detectors

1990 ◽  
Vol 34 ◽  
pp. 349-355
Author(s):  
Ralph G. Tissot ◽  
Michael O. Eatough
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Flow Through ◽  
Position Sensitive ◽  
Short Time ◽  
Position Sensitive Detectors ◽  
Time Frames

AbstractPosition sensitive proportional counters (PSPCs) increase the scope of X-ray diffraction analyses. High pressure flow through type PSPCs can significantly reduce data collecting times due to She ability for simultaneous data collection over large two-theta ranges. This inherent characteristic allows the diffraction user broad capabilities such as scanning very rapidly over large two- theta ranges or collecting data in real time over shorter two-theta ranges without scanning. Thus, we have been able to perform detailed high- temperature experiments in relatively short time frames, observe phase transitions and reactions as they occur, and perform unusual experiments such as observing the crystallization of a plasma spray in-situ.

scholarly journals Crystal Structures and High-Temperature Vibrational Spectra for Synthetic Boron and Aluminum Doped Hydrous Coesite

Crystals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 642 ◽  
Author(s):  
Yunfan Miao ◽  
Youwei Pang ◽  
Yu Ye ◽  
Joseph R. Smyth ◽  
Junfeng Zhang ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Single Crystals ◽  
Vibrational Spectra ◽  
Fourier Transformation ◽  
Ambient Pressure ◽  
Al Content ◽  
Al Substitution ◽  
Long Time

Coesite, a high-pressure SiO2 polymorph, has drawn extensive interest from the mineralogical community for a long time. In this study, we synthesized hydrous coesite samples with different B and Al concentrations at 5 and 7.5 GPa (1273 K). The B concentration could be more than 400 B/106Si with about 300 ppmw H2O, while the Al content can be as much as 1200 to 1300 Al/106Si with CH2O restrained to be less than 10 ppmw. Hence, B-substitution may prefer the mechanism of Si4+ = B3+ + H+, whereas Al-substitution could be dominated by 2Si4+ = 2Al3+ + OV. The doped B3+ and Al3+ cations may be concentrated in the Si1 and Si2 tetrahedra, respectively, and make noticeable changes in the Si–O4 and Si–O5 bond lengths. In-situ high-temperature Raman and Fourier Transformation Infrared (FTIR) spectra were collected at ambient pressure. The single crystals of coesite were observed to be stable up to 1500 K. The isobaric Grüneisen parameters (γiP) of the external modes (<350 cm−1) are systematically smaller in the Al-doped samples, as compared with those for the Al-free ones, while most of the OH-stretching bands shift to higher frequencies in the high temperature range up to ~1100 K

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.

In Situ High-Pressure and High-Temperature Experiments onn-Heptane

2012 ◽  
Vol 66 (2) ◽  
pp. 233-236 ◽  
Author(s):  
Erwei Qiao ◽  
Haifei Zheng ◽  
Changxing Long
Keyword(s):  
High Pressure ◽  
High Temperature

Evolution of Disordering in SiC under High Pressure High Temperature Conditions: In-situ Powder Diffraction Study

1998 ◽  
Vol 278-281 ◽  
pp. 612-617 ◽  
Author(s):  
Bogdan F. Palosz ◽  
Svetlana Stelmakh ◽  
Stanislaw Gierlotka ◽  
M. Aloszyna ◽  
Roman Pielaszek ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Diffraction Study ◽  
Powder Diffraction ◽  
Temperature Conditions ◽  
High Pressure High Temperature

Synthesize Ti3SiC2 and Ti3SiC2-Diamond Composites at High Pressure and High Temperature

2012 ◽  
Vol 512-515 ◽  
pp. 671-675 ◽  
Author(s):  
Ai Guo Zhou ◽  
Liang Li ◽  
Tai Chao Su ◽  
Shang Sheng Li
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Intermediate Products ◽  
Diamond Particles ◽  
Ternary Carbide ◽  
The Matrix

Ti3SiC2, a ternary carbide, was proposed at this paper to use as the binder of polycrystalline diamonds to overcome the weaknesses of traditional metal binders and ceramic binders. Ti3SiC2was first reported to be in-situ synthesized under high pressure (4GPa) and at high temperature (1400°C) (HPHT) from the mixtures of Ti, Si and graphite powders or the mixture of Ti, SiC and graphite powders. Ti3SiC2-damond composites were also made at HPHT from the previous mixtures and diamond particles. TiCx, Ti5Si3Cxand TiSi2were main impurities and/or intermediate products of Ti3SiC2samples synthesized at HPHT. Ti3SiC2content increased as synthesized time increased from 10 min to 60 min. For as-synthesized composites, diamond particles were evenly distributed in matrix. The diamond particles are bonded well with the matrix by three types of interface.

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