High-pressure Synchrotron X-ray Powder Diffraction Research Articles

Comparative Compressibility of Smectite Group under Anhydrous and Hydrous Environments.

High-pressure synchrotron X-ray powder diffraction studies of smectite group minerals (beidellite, montmorillonite, and nontronite) reveal comparative volumetric changes in the presence of different fluids, as pressure transmitting media (PTM) of silicone oil and distilled water for anhydrous and hydrous environments at room temperature. Using silicone oil PTM, all minerals show gradual contraction of unit-cell volumes and atomistic interplane distances. They, however, show abrupt collapse near 1.0 GPa under distilled water conditions due to hydrostatic to quasi-hydrostatic environmental changes of water PTM around samples concomitant with the transition from liquid to ICE-VI and ICE-VII. The degrees of volume contractions of beidellite, montmorillonite, and nontronite up to ca. 3 GPa are ca. 6.6%, 8.9%, and 7.5% with bulk moduli of ca. 38(1) GPa, 31(2) GPa, and 26(1) GPa under silicone oil pressure, whereas 13(1) GPa, 13(2) GPa, and 17(2) GPa, and 17(1) GPa, 20(1) GPa, and 21(1) GPa under hydrostatic and quasi-hydrostatic environments before and after 1.50 GPa, respectively.

W-rich mixed oxide solid solutions under pressure

We report high-pressure synchrotron X-ray powder diffraction data for the W-rich cubic ZrW2-xMoxO8 (x=0.4) up to 10 GPa with open decompression. This study shows that cubic- ZrW1.6Mo0.4O8 transforms to orthorhombic phase at the 5.04 GPa. Pressure-induced reversable amorphization of material was observed at 8.13 GPa. The obtained data suggest that W-rich cubic ZrW2-xMoxO8 (x=0.4) solid solutions are more attractive for creating products working under extreme conditions and mechanic stress.

Pressure induced change in the ZrWMoO8

In this paper we report high-pressure synchrotron x-ray powder diffraction data for the cubic ZrWMoO8. For the first time, extensive structural study of ZrWMoO8 solid solution as a function of pressure was performed. This study shows that disordered cubic-ZrWMoO8 (space group Pa3-) transforms to ordered cubic-ZrWMoO8 (space group P213) at low pressure. A further high-pressure influence leads followed by amorphization of the sample at 2.2 GPa. All transformations are irreversible. Our work will have high impact in the design of new composite materials with well-defined thermal expansion, especially for applications under extreme conditions and high mechanic stress.

Mechanical-pressure induced response of the MOF Al-MIL-53-TDC

The mechanical behavior of the recently synthesized flexible metal organic framework [Al(OH)(TDC)] with the well-known MIL-53 topology, built of 2,5-thiophenedicarboxylate (TDC2−) , OH– and Al3+ ions, named Al-MIL-53-TDC, has been explored using a combination of advanced characterization tools including mercury intrusion and high-pressure synchrotron X-ray powder diffraction, supported by Density Functional Theory calculations. This hybrid porous material was shown to exhibit a pressure-induced reversible structural contraction at ∼275 MPa associated with a unit cell volume change of ∼28.1% and a hysteresis loop once the pressure is released. This leads to an unprecedented energy work of 79 J g−1 that can be stored during one compression/decompression cycle for such a class of porous solids presenting a large-pore form ↔ closed-pore form phase transition. As such Al-MIL-53-TDC is at this time the best candidate of the MIL-53’s family for a future potential application where a nano-damper is required.

In situ high-pressure synchrotron X-ray powder diffraction study of tunnel manganese oxide minerals: hollandite, romanechite, and todorokite

In situ high-pressure synchrotron X-ray powder diffraction study of three tunnel manganese oxide minerals (hollandite with 2 × 2 MnO6 octahedra tunnels, romanechite with 2 × 3 tunnels, and todorokite with 3 × 3 tunnels) was performed using a diamond anvil cell and nominally penetrating alcohol and water mixture as a pressure-transmitting medium up to ~8 GPa. Bulk moduli (B 0) calculated using Murnaghan’s equation of state are inversely proportional to the size of the tunnel, i.e., 134(4) GPa for hollandite (I2/m), 108(2) GPa for romanechite (C2/m), and 67(5) GPa for todorokite (P2/m). On the other hand, axial compressibilities show different elastic anisotropies depending on the size of the tunnel, i.e., $$ \beta_{0}^{a} $$ (a/a 0) = −0.00066(3) GPa−1, $$ \beta_{0}^{b} $$ (b/b 0) = 0.00179(8) GPa−1, $$ \beta_{0}^{c} $$ (c/c 0) = 0.00637(4) GPa−1 [c > b > a] for hollandite; $$ \beta_{0}^{a} $$ (a/a 0) = 0.00485(4) GPa−1, $$ \beta_{0}^{b} $$ (b/b 0) = 0.0016(1) GPa−1, $$ \beta_{0}^{c} $$ (c/c 0) = 0.00199(8) GPa−1 [a > c > b] for romanechite; and $$ \beta_{0}^{a} $$ (a/a 0) = 0.00826(9) GPa−1, $$ \beta_{0}^{b} $$ (b/b 0) = 0.0054(1) GPa−1, $$ \beta_{0}^{c} $$ (c/c 0) = 0.00081(8) GPa−1 [a > b > c] for todorokite. Overall, the degree of tunnel distortion increases with increasing pressure and correlates with the size of the tunnel, which is evidenced by the gradual increases in the monoclinic β angles up to 3 GPa of 0.62°, 0.8°, and 1.15° in hollandite, romanechite, and todorokite, respectively. The compression of tunnel manganese oxides is related to the tunnel distortion and the size of the tunnel.

Pressure induced phase transition of PbNiO3 from LiNbO3-type to perovskite

The phase transition of PbNiO3 from LiNbO3 structure to the perovskite structure has been observed between 4.4 and 9.5GPa, which was investigated by high-pressure synchrotron x-ray powder diffraction at room temperature. Compression behavior of the two phases has been analyzed, and the c axis is the soft direction for LiNbO3-type PbNiO3. The bulk modulus of the LiNbO3-type PbNiO3 is K0=184(3)GPa, K0′=4.5(9), and the perovskite type is K0=166(8)GPa, K0′=4.9(8).

Super‐Hydrated Zeolites: Pressure‐Induced Hydration in Natrolites

High-pressure synchrotron X-ray powder diffraction studies of a series of alkali-metal-exchanged natrolites, A16Al16Si24O80·nH2O (A=Li, K, Na, Rb, and Cs and n=14, 16, 22, 24, 32), in the presence of water, reveal structural changes that far exceed what can be achieved by varying temperature and chemical composition. The degree of volume expansion caused by pressure-induced hydration (PIH) is inversely proportional to the non-framework cation radius. The expansion of the unit-cell volume through PIH is as large as 20.6% in Li-natrolite at 1.0 GPa and decreases to 6.7, 3.8, and 0.3% in Na-, K-, and Rb-natrolites, respectively. On the other hand, the onset pressure of PIH appears to increase with non-framework cation radius up to 2.0 GPa in Rb-natrolite. In Cs-natrolite, no PIH is observed but a new phase forms at 0.3 GPa with a 4.8% contracted unit cell and different cation-water configuration in the pores. In K-natrolite, the elliptical channel undergoes a unique overturn upon the formation of super-hydrated natrolite K16Al16Si24O80·32H2O at 1.0 GPa, a species that reverts back above 2.5 GPa as the potassium ions interchange their locations with those of water and migrate from the hinge to the center of the pores. Super-hydrated zeolites are new materials that offer numerous opportunities to expand and modify known chemical and physical properties by reversibly changing the composition and structure using pressure in the presence of water.

Structural properties of PbVO3 perovskites under hydrostatic pressure conditions up to 10.6 GPa

High-pressure synchrotron x-ray powder diffraction experiments were performed on PbVO3 tetragonal perovskite in a diamond anvil cell under hydrostatic pressures of up to 10.6 GPa at room temperature. The compression behavior of the PbVO3 tetragonal phase is highly anisotropic, with the c-axis being the soft direction. A reversible tetragonal to cubic perovskite structural phase transition was observed between 2.7 and 6.4 GPa in compression and below 2.2 GPa in decompression. This transition was accompanied by a large volume collapse of 10.6% at 2.7 GPa, which was mainly due to electronic structural changes of the V4+ ion. The polar pyramidal coordination of the V4+ ion in the tetragonal phase changed to an isotropic octahedral coordination in the cubic phase. Fitting the observed P–V data using the Birch–Murnaghan equation of state with a fixed of 4 yielded a bulk modulus K0 = 61(2) GPa and a volume V0 = 67.4(1) Å3 for the tetragonal phase, and the values of K0 = 155(3) GPa and V0 = 58.67(4) Å3 for the cubic phase. The first-principles calculated results were in good agreement with our experiments.

Pressure-Induced Isostructural Phase Transition and Correlation of FeAs Coordination with the Superconducting Properties of 111-Type Na1–xFeAs

The effect of pressure on the crystalline structure and superconducting transition temperature (T(c)) of the 111-type Na(1-x)FeAs system using in situ high-pressure synchrotron X-ray powder diffraction and diamond anvil cell techniques is studied. A pressure-induced tetragonal to tetragonal isostructural phase transition was found. The systematic evolution of the FeAs(4) tetrahedron as a function of pressure based on Rietveld refinements on the powder X-ray diffraction patterns was obtained. The nonmonotonic T(c)(P) behavior of Na(1-x)FeAs is found to correlate with the anomalies of the distance between the anion (As) and the iron layer as well as the bond angle of As-Fe-As for the two tetragonal phases. This behavior provides the key structural information in understanding the origin of the pressure dependence of T(c) for 111-type iron pnictide superconductors. A pressure-induced structural phase transition is also observed at 20 GPa.

Bulk modulus of basic sodalite, Na 8[AlSiO 4] 6(OH) 2·2H 2O, a possible zeolitic precursor in coal-fly-ash-based geopolymers

Synthetic basic sodalite, Na 8[AlSiO 4] 6(OH) 2·2H 2O, cubic, P43n, (also known as hydroxysodalite hydrate) was prepared by the alkaline activation of amorphous aluminosilicate glass, obtained from the phase separation of Class F fly ash. The sample was subjected to a process similar to geopolymerization, using high concentrations of a NaOH solution at 90 °C for 24 hours. Basic sodalite was chosen as a representative analogue of the zeolite precursor existing in Na-based Class F fly ash geopolymers. To determine its bulk modulus, high-pressure synchrotron X-ray powder diffraction was applied using a diamond anvil cell (DAC) up to a pressure of 4.5 GPa. A curve-fit with a truncated third-order Birch–Murnaghan equation of state with a fixed K' o = 4 to pressure-normalized volume data yielded the isothermal bulk modulus, K o = 43 ± 4 GPa, indicating that basic sodalite is more compressible than sodalite, possibly due to a difference in interactions between the framework host and the guest molecules.

Anisotropic compression of a synthetic potassium aluminogermanate zeolite with gismondine topology

Compression behaviour of a potassium aluminogermanate with a gismondine framework topology (K-AlGe-GIS) was studied using in-situ high-pressure synchrotron X-ray powder diffraction. In contrast to the potassium gallosilicate analogue (K-GaSi-GIS), no elastic anomaly due to pressure-induced hydration and/or cation relocation was observed in K-AlGe-GIS. The Birch–Murnaghan fit to the pressure–volume data results in a bulk modulus of B 0=31(1) GPa. The derived linear-axial compressibilities (i.e., β a =0.0065(5) GPa −1, β b =0.0196(4) GPa −1, β c =0.0081(7) GPa −1) indicate that the b-axis, normal to the 8-ring channels, is about three times more compressible than the a and c axes, parallel to the elliptical 8-ring channels. As a consequence a gradual flattening of the so-called ‘double crankshaft’ structural building units of the gismondine framework is observed. In K-AlGe-GIS, this flattening occurs almost linear with pressure, whereas it is nonlinear in the GaSi-analogue due to structural changes of the water–cation assembly under hydrostatic pressures.

Elastic behavior of zeolite boggsite in silicon oil and aqueous medium: A case of high-pressure-induced over-hydration

This paper reports the results of an in situ high-pressure synchrotron X-ray powder diffraction investigation on the natural zeolite boggsite [(K 0.06 Na 0.36 Sr 0.01 Ca 7.00 Mg 1.20 )(Al 17.52 Si 78.62 Fe 0.05 O 192 )·82.3 H 2 O]. The study was performed using both a (16:3:1) methanol:ethanol:water mixture (m.e.w.) as a nominally penetrating hydrostatic P-transmitting medium and silicon oil (s.o.) as a non-penetrating medium. The studied pressure ranges are: P amb -7.6 and P amb -5.9 GPa in m.e.w and s.o., respectively. No complete X-ray amorphization is observed up to the highest investigated pressures, and the original unit-cell parameters are almost completely recovered upon decompression in both media. The reductions of a, b, c, and V, within the pressure-ranges investigated, are 5.3, 4.2, 4.0, and 13.0% in s.o. and 4.1, 4.1, 3.8, and 11.5% in m.e.w. The Rietveld structural refinements of the powder patterns of the experiments in m.e.w. converged successfully up to 3.6 GPa and demonstrated the penetration of 13 additional water molecules between 0.3 and 2.9 GPa. This over-hydration occurs without any unit-cell volume expansion and can be explained by the fact that no new extraframework sites arise during compression and that water penetration is the only factor to increase the occupancy of already existing sites. Boggsite compressibility is higher in s.o. than in m.e.w. In particular, compressibility in m.e.w. is lower below 3 GPa, whereas above this pressure, the P- V trend becomes similar in the two media. This can be ascribed to the fact that, during water molecule penetration (0.3 < P < 3 GPa), the effect of the P-transmitting medium is directed to compress the system as well as to penetrate the channels.

Phase Transition and EOS of Cinnabar (α-HgS) at High Pressure and High Temperature

Phase relations and equation of state (EOS) of natural cinnabar (α-HgS) are investigated by high-pressure and high-temperature synchrotron x-ray powder diffraction. The unambiguous cinnabar–rocksalt structure phase boundaries are determined to be Plower (GPa) = 15.54 – 0.014T(°C) and Pupper(GPa) = 23.84 – 0.014T(°C) at 300–623K. With K′ fixed at 4, we obtain K0 = 37(4)GPa, (δK/δT)P = −0.025(2) GPaK−1, and α0 = 3.79(20) × 10−5 K−1 for the cinnabar phase of α-HgS. The (δK/δT)P and α0 of cinnabar phase are obtained for the first time. A nearly isotropic compression of cinnabar phase is observed by linear regressions.

Non-hydrostatic compression of zeolite NaA in water medium: connection to anomalous conductivity

High-pressure synchrotron X-ray powder diffraction measurements of a synthetic zeolite NaA were carried out up to 2.5 GPa using pure water as pressure-transmitting (P) medium to provide non-hydrostatic (wet) conditions in a diamond anvil cell. The compressibility of wet zeolite NaA is similar to that measured at hydrostatic compression in water within the P-range 0-0.8 GPa, whereas between 1-2 GPa the zeolite becomes slightly more compressible and progressively amorphizes due to the non-hydrostatic conditions. Rietveld refinement at 0.37 GPa reveals a selective additional filling of the H 2 O sites in α- and β-cage, leading to about 30% increase of the total water content. The over-hydrated state of the zeolite is partially preserved after the pressure release. The over-hydration of zeolite pores, combined with a partial disordering at the onset of amorphization, apparently provides necessary conditions for the P-induced enhancement of water-cationic diffusion and the corresponding increase of ionic conductivity observed in zeolite NaA in non-hydrostatic water medium.

High-pressure synchrotron X-ray powder diffraction studies of zeolites

Zeolites are crystalline porous aluminosilicate framework solids. Although there are many reports of how the structures change as a function of temperature, similar studies as a function of high pressure are relatively scarce. With the increasing availability of synchrotron X-ray sources and greater knowledge in the chemistry community of high pressure techniques this is gradually changing. Still, only a handful of the many zeolite topologies have been studied. In this short review the behaviour of two zeolite systems, those with the LTA and FAU topology, under hydrostatic pressure conditions will be discussed. The results clearly demonstrate the rich behaviour that is observed when the solids are pressurized in the presence of a liquid with molecules that are small enough to enter the pores.

Pressure induced octahedral tilting distortion in Ba2YTaO6

Herein we communicate the first example of a pressure induced octahedral tilting distortion in a double perovskite phase, which was observed during the structural characterization of Ba2YTaO6 using high-pressure synchrotron X-ray powder diffraction.

Synchrotron X-ray powder diffraction and computational investigation of purely siliceous zeolite Y under pressure.

High-pressure synchrotron X-ray powder diffraction measurements of a sample of purely siliceous zeolite Y (faujasite) were carried out up to 8.0 GPa at room temperature using a diamond anvil cell. Measurements using silicone oil as the pressure-transmitting medium show compression of the zeolite followed by a loss of long-range ordering at 2.2 GPa. The experimentally determined bulk modulus, 38(2) GPa, is, within experimental error, identical to that of quartz. When using a methanol:ethanol:water mixture (16:3:1) as the pressure-transmitting medium, two distinct compressibility regions are observed with a dramatic change in the compression mechanism at 4 GPa. Rietveld refinement analysis of the powder patterns provides a detailed description of the underlying chemistry, with sequential pore filling the main response up to 4 GPa and framework distortions at higher pressures.

The equation of state of PbTiO3 up to 37 GPa: a synchrotron x-ray powderdiffraction study

High-pressure synchrotron x-ray powder diffraction patterns were collected usingID09 of ESRF (Grenoble, France) for a powder sample of PbTiO3, placed in adiamond anvil cell. The patterns were collected at room temperature usingnitrogen (up to 37 GPa) and methanol–ethanol solution (up to 7 GPa) aspressure-transmitting media. The bulk moduli were calculated for the first timeusing the Vinet equation of state and they were compared to those of isostructuralcompounds. The trend of the spontaneous polarization as a function of pressureconfirms that the ferroelectric–paraelectric phase transition at 11.2 GPa possessesa second-order character.

High-pressure structures of alpha- and delta-ZrMo2O8.

In situ high-pressure synchrotron X-ray powder diffraction studies of trigonal alpha-ZrMo(2)O(8), zirconium molybdate, have been performed from ambient conditions to 1.9 GPa, over the alpha-delta phase transition at 1.06-1.11 GPa. The monoclinic structure of delta-ZrMo(2)O(8), stable between 1.1 and 2.5 GPa at 298 K, has been solved by direct methods and refined using the Rietveld method. Significant distortions of the ZrO(6) and MoO(4) polyhedral elements are observed for delta-ZrMo(2)O(8), as compared to the ambient conditions of the alpha-phase, while the packing of anions becomes more symmetric at high pressure.

High-pressure properties of TiP2O7, ZrP2O7and ZrV2O7

High-pressure synchrotron X-ray powder diffraction studies of TiP2O7, ZrP2O7and ZrV2O7have been performed. The ZrV2O7structure undergoes a reversible transition at 1.38–1.58 GPa from cubic α- to pseudo-tetragonal β-ZrV2O7that displays an orthorhombic 2 × 3 × 3 supercell. At pressures above 4 GPa, ZrV2O7becomes irreversibly X-ray amorphous. No such transformations are observed for TiP2O7and ZrP2O7, which compress smoothly up to the highest investigated pressures (40.3 and 20.5 GPa, respectively). These differences in high-pressure properties are discussed in terms of the negative thermal expansion of ZrV2O7. The bulk moduli at ambient pressure (B0) for TiP2O7, ZrP2O7, α-ZrV2O7and β-ZrV2O7were estimated to be 42 (3), 39 (1), 17.0 (7) and 20.8 (10) GPa, respectively.