High-pressure phase transformation in MnCO3: a synchrotron XRD study

2006 ◽  
Vol 71 (1) ◽  
pp. 105-111 ◽  
Author(s):  
S. Ono
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Unit Cell ◽  
Manganese Carbonate ◽  
Orthorhombic Unit Cell ◽  
Direct Formation ◽  
Diamond Anvil ◽  
Pressure Form ◽  
Compression Data ◽  
Laser Heated

AbstractThe high-pressure behaviour of manganese carbonate was investigated by in situ synchrotron X-ray powder diffraction up to 54 GPa with a laser-heated diamond anvil cell. A phase transition from rhodochrosite to a new structure form was observed at 50 GPa after laser heating. The diffraction pattern of the new high-pressure form was reasonably indexed with an orthorhombic unit-cell with a = 5.361 A, b = 8.591 A and c = 9.743 Å. The pressure-induced phase transition implies a unit-cell volume reduction of ∼5%. This result does not support the direct formation of diamond by dissociation of solid state MnCO3 reported in a previous study. Fitting the compression data of rhodochrosite to a second-order Birch-Murnaghan equation of state (Ko’ = 4) gives K0 = 126(±10) GPa. The c axis of the unit-cell parameter was more compressive than the a axis.

Characterization of the pressure-induced second-order phase transition in the mixed-valence vanadate BaV6O11

2009 ◽  
Vol 65 (3) ◽  
pp. 326-333 ◽  
Author(s):  
Karen Friese ◽  
Yasushi Kanke ◽  
Andrzej Grzechnik
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Cell Volume ◽  
Unit Cell Volume ◽  
Ambient Pressure ◽  
Mixed Valence ◽  
Volume Effect ◽  
Unit Cell ◽  
Additional Degree ◽  
Diamond Anvil

The pressure dependence of the structure of the mixed-valence vanadate BaV6O11 was studied with single-crystal X-ray diffraction in a diamond–anvil cell. The compressibility data could be fitted with a Murnaghan equation of state with the zero-pressure bulk modulus B 0 = 161 (7) GPa and the unit-cell volume at ambient pressure = 387.1 (3) Å^3 (B′ = 4.00). A phase transition involving a symmetry reduction from P63/mmc to P63 mc can be reliably detected in the high-pressure data. The estimated transition pressure lies in the range 1.18 < P c < 3.09 GPa. The transition leads to a breaking of the regular Kagomé net formed by part of the V ions. While in the ambient pressure structure all V—V distances in the Kagomé net are equal, they split into inter-trimer and intra-trimer distances in the high-pressure phase. In general, these changes are comparable to those observed in the corresponding low-temperature transition. However, the pressure-induced transition takes place at a lower unit-cell volume compared with the temperature-induced transition. Furthermore, overall trends for inter-trimer and intra-trimer V—V distances as a function of the unit-cell volume are clearly different for datapoints obtained by variation of pressure and temperature. The behavior of BaV6O11 is compared with that of NaV6O11. While in the latter compound the transition can be explained as a pure volume effect, in BaV6O11 an additional degree of freedom related to the valence distribution among the symmetrically independent vanadium sites has to be taken into account.

Crystal structures and electronic properties of Sn3N4 polymorphs synthesized via high-pressure nitridation of tin

CrystEngComm ◽  
2020 ◽  
Vol 22 (20) ◽  
pp. 3531-3538
Author(s):  
Ken Niwa ◽  
Tomoya Inagaki ◽  
Tetsu Ohsuna ◽  
Zheng Liu ◽  
Takuya Sasaki ◽  
...  
Keyword(s):  
High Pressure ◽  
Electronic Properties ◽  
Crystal Structures ◽  
Crystal Chemistry ◽  
Diamond Anvil Cell ◽  
Functional Materials ◽  
Group Iva ◽  
Diamond Anvil ◽  
Laser Heated ◽  
Insight Into

Sn3N4 polymorphs were synthesized via high-pressure nitridation of tin by means of laser-heated diamond anvil cell technique. This implies new insight into the crystal chemistry and functional materials of group IVA nitrides.

Reaction of titanium with carbon in a laser heated diamond anvil cell and reevaluation of a proposed pressure-induced structural phase transition of TiC

2009 ◽  
Vol 478 (1-2) ◽  
pp. 392-397 ◽  
Author(s):  
Björn Winkler ◽  
Erick A. Juarez-Arellano ◽  
Alexandra Friedrich ◽  
Lkhamsuren Bayarjargal ◽  
Jinyuan Yan ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Diamond Anvil Cell ◽  
Structural Phase ◽  
Diamond Anvil ◽  
Laser Heated

scholarly journals The Phase Transition and Dehydration in Epsomite under High Temperature and High Pressure

Crystals ◽  
2020 ◽  
Vol 10 (2) ◽  
pp. 75 ◽  
Author(s):  
Linfei Yang ◽  
Lidong Dai ◽  
Heping Li ◽  
Haiying Hu ◽  
Meiling Hong ◽  
...  
Keyword(s):  
Phase Transition ◽  
Electrical Conductivity ◽  
High Pressure ◽  
High Temperature ◽  
Magnesium Sulfate ◽  
Room Temperature ◽  
Diamond Anvil Cell ◽  
Vibrational Modes ◽  
Diamond Anvil ◽  
T Phase

The phase stability of epsomite under a high temperature and high pressure were explored through Raman spectroscopy and electrical conductivity measurements in a diamond anvil cell up to ~623 K and ~12.8 GPa. Our results verified that the epsomite underwent a pressure-induced phase transition at ~5.1 GPa and room temperature, which was well characterized by the change in the pressure dependence of Raman vibrational modes and electrical conductivity. The dehydration process of the epsomite under high pressure was monitored by the variation in the sulfate tetrahedra and hydroxyl modes. At a representative pressure point of ~1.3 GPa, it was found the epsomite (MgSO4·7H2O) started to dehydrate at ~343 K, by forming hexahydrite (MgSO4·6H2O), and then further transformed into magnesium sulfate trihydrate (MgSO4·3H2O) and anhydrous magnesium sulfate (MgSO4) at higher temperatures of 373 and 473 K, respectively. Furthermore, the established P-T phase diagram revealed a positive relationship between the dehydration temperature and the pressure for epsomite.

The Use of Quartz as an Internal Pressure Standard in High-Pressure Crystallography

1997 ◽  
Vol 30 (4) ◽  
pp. 461-466 ◽  
Author(s):  
R. J. Angel ◽  
D. R. Allan ◽  
R. Miletich ◽  
L. W. Finger
Keyword(s):  
High Pressure ◽  
Equation Of State ◽  
Order Equation ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Third Order ◽  
Single Crystal Diffraction ◽  
Cell Parameters ◽  
Diamond Anvil ◽  
Pressure Standard

The unit-cell parameters of quartz, SiO2, have been determined by single-crystal diffraction at 22 pressures to a maximum pressure of 8.9 GPa (at room temperature) with an average precision of 1 part in 9000. Pressure was determined by the measurement of the unit-cell volume of CaF2 fluorite included in the diamond-anvil pressure cell. The variation of quartz unit-cell parameters with pressure is described by: a −4.91300 (11) = −0.0468 (2) P + 0.00256 (7) P 2 − 0.000094 (6) P 3, c − 5.40482 (17) = − 0.03851 (2) P + 0.00305 (7) P 2 − 0.000121 (6) P 3, where P is in GPa and the cell parameters are in ångstroms. The volume–pressure data of quartz are described by a Birch–Murnaghan third-order equation of state with parameters V 0 = 112.981 (2) å3, K T0 = 37.12 (9) GPa and K′ = 5.99 (4). Refinement of K′′ in a fourth-order equation of state yielded a value not significantly different from the value implied by the third-order equation. The use of oriented quartz single crystals is proposed as an improved internal pressure standard for high-pressure single-crystal diffraction experiments in diamond-anvil cells. A measurement precision of 1 part in 10 000 in the volume of quartz leads to a precision in pressure measurement of 0.009 GPa at 9 GPa.

High-pressure transformations of NbO2F

2000 ◽  
Vol 56 (2) ◽  
pp. 189-196 ◽  
Author(s):  
Stefan Carlson ◽  
Ann-Kristin Larsson ◽  
Franziska E. Rohrer
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
High Pressures ◽  
Ambient Pressure ◽  
Close Packing ◽  
Hexagonal Close Packing ◽  
Rietveld Refinements ◽  
X Ray ◽  
Anion Coordination ◽  
Diamond Anvil

The ReO3-type structure NbO2F, niobium dioxyfluoride, has been studied at high pressures using diamond anvil cells and synchrotron X-ray radiation. High-pressure powder diffraction measurements have been performed up to 40.1 GPa. A phase transition from the cubic (Pm3¯m) ambient pressure structure to a rhombohedral (R3¯c) structure at 0.47 GPa has been observed. Rietveld refinements at 1.38, 1.96, 3.20, 6.23, 9.00 and 10.5 GPa showed that the transition involves an a − a − a − tilting of the cation–anion coordination octahedra and a change of the anion–anion arrangement to approach hexagonal close packing. Compression and distortion of the Nb(O/F)6 octahedra is also revealed by the Rietveld refinements. At 17–18 GPa, the diffraction pattern disappears and the structure becomes X-ray amorphous.

Sign in / Sign up

Export Citation Format

Share Document