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.

β-CaB4O7: A New Polymorph Synthesized under High-Pressure/High-Temperature Conditions

2003 ◽  
Vol 58 (4) ◽  
pp. 257-265 ◽  
Author(s):  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Prominent Feature ◽  
X Ray ◽  
Temperature Conditions ◽  
High Pressure High Temperature ◽  
Ir Spectroscopic ◽  
Pressure Phase

A new oxoborate β -CaB4O7 has been synthesized under high-pressure/high-temperature conditions from calcium oxide and boron oxide with a Walker-type multianvil apparatus at 7.7 GPa and 1100 °C. Single crystal X-ray structure determination of β -CaB4O7 revealed: Pmn21, a = 1058.4(1), b = 436.9(1), c = 419.4(1) pm, Z = 2, R1 = 0.0305, wR2 = 0.0587 (all data). The compound is isotypic to the known oxoborates SrB4O7, PbB4O7, and EuB4O7 exhibiting a network structure of linked BO4 tetrahedra. As a prominent feature of the tetrahedral network an oxygen atom is coordinated to three boron atoms. The relation of the crystal structure of the high-pressure phase β -CaB4O7 to the normalpressure phase α-CaB4O7 as well as the relation to the isotypic phases MB4O7 (M = Sr, Pb, Eu) are discussed. The results of IR-spectroscopic investigations on β -CaB4O7 are also presented.

High-Pressure Synthesis, Crystal Structure, And Properties Of δ-Ce(Bo2)3

2007 ◽  
Vol 62 (6) ◽  
pp. 759-764 ◽  
Author(s):  
Almut Haberer ◽  
Gunter Heymann ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Diffraction Data ◽  
Structure And Properties ◽  
X Ray Diffraction ◽  
X Ray ◽  
High Pressure High Temperature ◽  
Pressure Synthesis ◽  
Pressure Phase

The cerium meta-oxoborate δ -Ce(BO2)3 was synthesized under high-pressure / high-temperature conditions of 3.5 GPa and 1050 °C in a Walker-type multianvil apparatus. The crystal structure was determined by single crystal X-ray diffraction data, collected at r. t. The compound crystallizes monoclinicly in the space group P21/c with the lattice parameters a = 422.52(8), b = 1169.7(2), c = 725.2(2) pm, and β = 91.33(3)°. The structure is isotypic to the recently published high-pressure phase δ -La(BO2)3, consisting exclusively of corner sharing [BO4]5− tetrahedra

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

High-Pressure Synthesis and Crystal Structure of the New Orthorhombic Polymorph β-HgB4O7

2005 ◽  
Vol 60 (8) ◽  
pp. 815-820 ◽  
Author(s):  
Holger Emme ◽  
Matthias Weil ◽  
Hubert Huppertz
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Ambient Pressure ◽  
Normal Pressure ◽  
High Pressure Phase ◽  
Synthesis And Crystal Structure ◽  
Space Group ◽  
High Pressure Synthesis ◽  
Pressure Synthesis ◽  
Pressure Phase

The new orthorhombic polymorph β-HgB4O7 has been synthesized under high-pressure and hightemperature conditions in a Walker-type multianvil apparatus at 7.5 GPa and 600 °C. β-HgB4O7 is isotypic to the known ambient pressure phases MB4O7 (M = Sr, Pb, Eu) and the high-pressure phase β-CaB4O7 crystallizing with two formula units in the space group Pmn21 with lattice parameters a = 1065.6(2), b = 438.10(9), and c = 418.72(8) pm. The relation of the crystal structure of the high-pressure phase β-HgB4O7 to the normal pressure phase α-HgB4O7 as well as the relation to the isotypic phases MB4O7 (M = Sr, Pb, Eu) and β-CaB4O7 are discussed.

Neutron Diffraction Study of the Ambient-Pressure, Rutile-Type and the High-Pressure, CaCl2-Type Phases of Ruthenium Dioxide

1997 ◽  
Vol 53 (6) ◽  
pp. 880-884 ◽  
Author(s):  
J. Haines ◽  
J. M. Léger ◽  
O. Schulte ◽  
S. Hull
Keyword(s):  
High Pressure ◽  
Soft Mode ◽  
Ambient Pressure ◽  
Neutron Diffraction Study ◽  
Normal Coordinate ◽  
Oxygen Ions ◽  
Type Phase ◽  
Principal Axes ◽  
Pressure Phase

The structures of the ambient-pressure, rutile-type and the high-pressure, CaCl2-type phases of RuO2 were refined by time-of-flight neutron powder diffraction. Refinement of the data obtained from the ambient-pressure phase (P42/mnm, Z = 2) yielded cell constants a = 4.49307 (7) and c = 3.10639 (7) Å and an oxygen positional parameter x = 0.3056 (1). The principal axes of the displacement ellipsoids of the oxygen ions lie along the directions which correspond to the normal coordinate of the B 1g soft mode that drives the transition to the CaCl2-type structure. The CaCl2-type phase (Pnnm, Z = 2) was refined in situ at 5.3 (3) GPa and the following cell constants and oxygen positional parameters were obtained: a = 4.4865 (5), b = 4.4347 (5), c = 3.0934 (3) Å, x = 0.3101 (5) and y = 0.3005 (5). In the CaCl2-type phase at 5.3 (3) GPa the RuO6 octahedra are rotated by 1.1 (2)° with respect to their orientation in the ruffle-type phase. There is little change in the internal angles of the octahedron between 0.1 MPa and 5.3 GPa. Compression of the octahedron is anisotropic with a much greater reduction of the Ru—O contacts in the ab plane.

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>

In situ Raman study of C60 polymerization at high pressure high temperature conditions

2002 ◽  
Vol 116 (5) ◽  
pp. 2166-2174 ◽  
Author(s):  
A. V. Talyzin ◽  
L. S. Dubrovinsky ◽  
T. Le Bihan ◽  
U. Jansson
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
In Situ Raman ◽  
Temperature Conditions ◽  
High Pressure High Temperature ◽  
Raman Study

In situ high pressure synthesis of cBN-based composites

2014 ◽  
Vol 07 (04) ◽  
pp. 1450040 ◽  
Author(s):  
Yanan Xue ◽  
Jiaqian Qin ◽  
Xinyu Zhang ◽  
Mingzhen Ma ◽  
Duanwei He ◽  
...  
Keyword(s):  
High Pressure ◽  
Elastic Modulus ◽  
High Temperature ◽  
Cubic Boron Nitride ◽  
Cutting Performance ◽  
High Pressure Sintering ◽  
Phase Combination ◽  
Pressure Synthesis ◽  
New Compounds

Vickers hardness, phase combination, elastic modulus and cutting performance of the cubic boron nitride (cBN) based composites with different cBN weight ratios sintered at high pressure and high temperature were investigated. During high-pressure sintering, reactions occurred between cBN and Ti 3 SiC 2, then new compounds, TiB 2, C 0.7 N 0.3 Ti , SiC and SiB 4 were formed, and no hBN phase was observed. Bulk modulus and hardness of the cBN composites decreased with increasing Ti 3 SiC 2 contents in raw mixture, and the highest hardness of 35.9 GPa was achieved for 95 wt.% cBN–5 wt.% Ti 3 SiC 2 composition specimen sintered at 1600°C. In addition, the present cBN-based composites exhibited good cutting performance.

In situ measurements of the orthorhombic-to-trigonal transition inBaSi2sunder high-pressure and high-temperature conditions

1997 ◽  
Vol 55 (1) ◽  
pp. 132-135 ◽  
Author(s):  
Motoharu Imai ◽  
Toshiyuki Hirano ◽  
Takumi Kikegawa ◽  
Osamu Shimomura
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
In Situ Measurements ◽  
Temperature Conditions

scholarly journals Carbide Formation in Refractory Mo15Nb20Re15Ta30W20 Alloy under a Combined High-Pressure and High-Temperature Condition

Entropy ◽  
2020 ◽  
Vol 22 (7) ◽  
pp. 718
Author(s):  
Congyan Zhang ◽  
Uttam Bhandari ◽  
Congyuan Zeng ◽  
Huan Ding ◽  
Shengmin Guo ◽  
...  
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Mechanical Performance ◽  
Ambient Pressure ◽  
High Entropy Alloy ◽  
Carbide Formation ◽  
High Entropy ◽  
Temperature Conditions ◽  
High Pressure High Temperature ◽  
Diamond Anvil

In this work, the formation of carbide with the concertation of carbon at 0.1 at.% in refractory high-entropy alloy (RHEA) Mo15Nb20Re15Ta30W20 was studied under both ambient and high-pressure high-temperature conditions. The x-ray diffraction of dilute carbon (C)-doped RHEA under ambient pressure showed that the phases and lattice constant of RHEA were not influenced by the addition of 0.1 at.% C. In contrast, C-doped RHEA showed unexpected phase formation and transformation under combined high-pressure and high-temperature conditions by resistively employing the heated diamond anvil cell (DAC) technique. The new FCC_L12 phase appeared at 6 GPa and 809 °C and preserved the ambient temperature and pressure. High-pressure and high-temperature promoted the formation of carbides Ta3C and Nb3C, which are stable and may further improve the mechanical performance of the dilute C-doped alloy Mo15Nb20Re15Ta30W20.

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