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12 items found (0 items not approved), displaying 1 to 10.[First/Prev] 1, 2 [Next/Last]

Instruments / Technical Area	Publication Details	Published
I15-Extreme Conditions	Joint experimental and theoretical study of bulk Y2O3 at high pressure A. L. J. Pereira , J. A. Sans , O. Gomis , D. Santamaria-Perez , S. Ray , A. Godoy , A. S. Da Silva-Sobrinho , P. Rodríguez-Hernández , A. Muñoz , C. Popescu , F. J. Manjon Results In Physics 8 DOI: 10.1016/j.rinp.2023.106499 Diamond Proposal Number(s): [6073] Open Access Show Abstract ▼ Abstract: We report a joint experimental and theoretical study of the structural and vibrational properties of C-type bulk Y2O3 under hydrostatic compression. The combination of high-pressure X-ray diffraction and Raman scattering experimental measurements with ab initio theoretical calculations on bulk Y2O3 allows us to confirm the cubic (C-type) - monoclinic (B-type) - trigonal (A-type) phase transition sequence on the upstroke and the trigonal-monoclinic phase transition on the downstroke. This result reconciles with the results already found in related rare-earth sesquioxides of cations with similar ionic radii as Y, such as Ho2O3 and Dy2O3, and ends with the controversy regarding the existence of the intermediate monoclinic phase between the cubic and trigonal phases in pure bulk Y2O3 on the upstroke. As a byproduct, the good agreement between experimental and calculated results allows us to use extensive theoretical data to discuss the structural and vibrational behavior of the three phases of Y2O3 under compression, thus allowing a more detailed understanding of the effect of pressure on rare-earth sesquioxides than previous studies.	May 2023
I19-Small Molecule Single Crystal Diffraction	Unveiling the role of the lone electron pair in sesquioxides at high pressure: compressibility of β-Sb2O3 Juan Angel Sans , Francisco Javier Manjon , André Luis De Jesus Pereira , Javier Ruiz-Fuertes , Catalin Popescu , Alfonso Muñoz , Plácida Rodríguez-Hernández , Julio Pellicer-Porres , Vanesa Paula Cuenca-Gotor , Julia Contreras-Garcia , Jordi Ibañez , Virginia Monteseguro Dalton Transactions 854 DOI: 10.1039/D1DT00268F Diamond Proposal Number(s): [22223] Show Abstract ▼ Abstract: The structural, vibrational and electronic properties of the compressed β-Sb2O3 polymorph, a.k.a. mineral valentinite, have been investigated in a joint experimental and theoretical study up to 23 GPa. The compressibility of the lattice parameters, unit-cell volume and polyhedral unit volume as well as the behaviour of its Raman- and IR-active modes under compression have been interpreted on the basis of ab initio theoretical simulations. Valentinite shows an unusual compressibility up to 15 GPa with four different pressure ranges, whose critical pressures are 2, 4, and 10 GPa. The pressure dependence of the main structural units, the lack of soft phonons, and the electronic density charge topology address the changes at those critical pressures to isostructural phase transitions of degree higher than 2. In particular, the transitions at 2 and 4 GPa can be ascribed to the changes in the interaction between the stereochemically-active lone electron pairs of Sb atoms under compression. The changes observed above 10 GPa, characterized by a general softening of several Raman- and IR-active modes, point to a structural instability prior to the 1st-order transition occurring above 15 GPa. Above this pressure, a tentative new high-pressure phase (s.g. Pcc2) has been assigned by single-crystal and powder X-ray diffraction measurements.	Mar 2021
I15-Extreme Conditions	The phase diagram of Ti-6Al-4V at high-pressures and high-temperatures Simon Macleod , Daniel Errandonea , Geoffrey Adam Cox , Hyunchae Cynn , Dominik Daisenberger , Sarah Finnegan , Malcolm Mcmahon , Keith Munro , Catalin Popescu , Christian Storm Journal Of Physics: Condensed Matter DOI: 10.1088/1361-648X/abdffa Diamond Proposal Number(s): [8176, 9366] Show Abstract ▼ Abstract: We report results from a series of diamond-anvil-cell synchrotron X-ray diffraction and largevolume- press experiments, and calculations, to investigate the phase diagram of commercial polycrystalline high-strength Ti-6Al-4V alloy in pressure-temperature space. Up to ~30 GPa and 886 K, Ti- 6Al-4V is found to be stable in the hexagonal-close-packed, or alpha phase. The effect of temperature on the volume expansion and compressibility of alpha-Ti-6Al-4V is modest. The martensitic alpha→omega (hexagonal) transition occurs at ~30 GPa, with both phases coexisting until further compression to ~38-40 GPa completes the transition to the omega phase. Between 300 K and 844 K the alpha→omega transition appears to be independent of temperature. Omega-Ti-6Al-4V is stable to ~91 GPa and 844 K, the highest combined pressure and temperature reached in these experiments. Pressure-volume-temperature equations-of-state for the alpha and omega phases of Ti- 6Al-4V are generated and found to be similar to pure Ti. A pronounced hysteresis is observed in the omega-Ti-6Al-4V on decompression, with the hexagonal structure reverting back to the  alpha phase at pressures below ~9 GPa at room temperature, and at a higher pressure at elevated temperatures. Based on our data, we estimate the Ti-6Al-4V alpha-beta-omega triple point to occur at ~900 K and 30 GPa, in good agreement with our calculations.	Jan 2021
I15-Extreme Conditions	Characterization and decomposition of the natural van der Waals SnSb2Te4 under compression Juan A. Sans , Rosario Vilaplana , E. Lora Da Silva , Catalin Popescu , Vanesa P. Cuenca-Gotor , Adrián Andrada-Chacón , Javier Sánchez-Benitez , Oscar Gomis , André L. J. Pereira , Plácida Rodríguez-Hernández , Alfonso Muñoz , Dominik Daisenberger , Braulio Garcia-Domene , Alfredo Segura , Daniel Errandonea , Ravhi S. Kumar , Oliver Oeckler , Philipp Urban , Julia Contreras-Garcia , Francisco J. Manjón Inorganic Chemistry DOI: 10.1021/acs.inorgchem.0c01086 Show Abstract ▼ Abstract: High pressure X-ray diffraction, Raman scattering, and electrical measurements, together with theoretical calculations, which include the analysis of the topological electron density and electronic localization function, evidence the presence of an isostructural phase transition around 2 GPa, a Fermi resonance around 3.5 GPa, and a pressure-induced decomposition of SnSb2Te4 into the high-pressure phases of its parent binary compounds (α-Sb2Te3 and SnTe) above 7 GPa. The internal polyhedral compressibility, the behavior of the Raman-active modes, the electrical behavior, and the nature of its different bonds under compression have been discussed and compared with their parent binary compounds and with related ternary materials. In this context, the Raman spectrum of SnSb2Te4 exhibits vibrational modes that are associated but forbidden in rocksalt-type SnTe; thus showing a novel way to experimentally observe the forbidden vibrational modes of some compounds. Here, some of the bonds are identified with metavalent bonding, which were already observed in their parent binary compounds. The behavior of SnSb2Te4 is framed within the extended orbital radii map of BA2Te4 compounds, so our results pave the way to understand the pressure behavior and stability ranges of other “natural van der Waals” compounds with similar stoichiometry.	Jul 2020
I15-Extreme Conditions	The high-pressure, high-temperature phase diagram of cerium Keith Munro , Dominik Daisenberger , Simon Macleod , Steve Mcguire , Ingo Loa , Catalin Popescu , Pablo Botella , Daniel Errandonea , Malcolm Mcmahon Journal Of Physics: Condensed Matter DOI: 10.1088/1361-648X/ab7f02 Diamond Proposal Number(s): [9548, 7533] Open Access Show Abstract ▼ Abstract: We present an experimental study of the high-pressure, high-temperature behaviour of cerium up to $\sim$22 GPa and 820 K using angle-dispersive x-ray diffraction and external resistive heating. Studies above 820 K were prevented by chemical reactions between the samples and the diamond anvils of the pressure cells. We unambiguously measure the stability region of the orthorhombic \textit{oC}4 phase and find it reaches its apex at 7.1 GPa and 650 K. We locate the $\alpha$-\textit{cF}4 -- \textit{oC}4 -- \textit{tI}2 triple point at 6.1 GPa and 640 K, 1 GPa below the location of the apex of the \textit{oC}4 phase, and 1-2 GPa lower than previously reported. We find the $\alpha$-\textit{cF}4 $\rightarrow$ \textit{tI}2 phase boundary to have a positive gradient of 280 K/GPa, less steep than the 670 K/GPa reported previously, and find the \textit{oC}4 $\rightarrow$ \textit{tI}2 phase boundary to lie at higher temperatures than previously found. We also find variations as large as 2-3 GPa in the transition pressures at which the \textit{oC}4 $\rightarrow$ \textit{tI}2 transition takes place at a given temperature, the reasons for which remain unclear. Finally, we find no evidence that the $\alpha$-\textit{cF}4 $\rightarrow$ \textit{tI}2 is not second order at all temperatures up to 820 K.	Mar 2020
I15-Extreme Conditions	Thermal equation of state of ruthenium characterized by resistively heated diamond anvil cell Simone Anzellini , Daniel Errandonea , Claudio Cazorla , Simon Macleod , Virginia Monteseguro , Silvia Boccato , Enrico Bandiello , Daniel Diaz Anichtchenko , Catalin Popescu , Christine M. Beavers Scientific Reports 9 DOI: 10.1038/s41598-019-51037-8 Diamond Proposal Number(s): [23122] Open Access Show Abstract ▼ Abstract: The high-pressure and high-temperature structural and chemical stability of ruthenium has been investigated via synchrotron X-ray diffraction using a resistively heated diamond anvil cell. In the present experiment, ruthenium remains stable in the hcp phase up to 150 GPa and 960 K. The thermal equation of state has been determined based upon the data collected following four different isotherms. A quasi-hydrostatic equation of state at ambient temperature has also been characterized up to 150 GPa. The measured equation of state and structural parameters have been compared to the results of ab initio simulations performed with several exchange-correlation functionals. The agreement between theory and experiments is generally quite good. Phonon calculations were also carried out to show that hcp ruthenium is not only structurally but also dynamically stable up to extreme pressures. These calculations also allow the pressure dependence of the Raman-active E2g mode and the silent B1g mode of Ru to be determined.	Oct 2019
I15-Extreme Conditions	Phase diagram of calcium at high pressure and high temperature S. Anzellini , D. Errandonea , Simon Macleod , P. Botella , D. Daisenberger , J. M. De’ath , J. Gonzalez-Platas , J. Ibáñez , M. I. Mcmahon , K. A. Munro , C. Popescu , J. Ruiz-Fuertes , C. W. Wilson Physical Review Materials 2 DOI: 10.1103/PhysRevMaterials.2.083608 Diamond Proposal Number(s): [15864] Show Abstract ▼ Abstract: Resistively heated diamond-anvil cells have been used together with synchrotron x-ray diffraction to investigate the phase diagram of calcium up to 50 GPa and 800 K. The phase boundaries between the Ca-I (fcc), Ca-II (bcc), and Ca-III (simple cubic, sc) phases have been determined at these pressure-temperature conditions, and the ambient temperature equation of state has been generated. The equation of state parameters at ambient temperature have been determined from the experimental compression curve of the observed phases by using third-order Birch-Murnaghan and Vinet equations. A thermal equation of state was also determined for Ca-I and Ca-II by combining the room-temperature Birch-Murnaghan equation of state with a Berman-type thermal expansion model.	Aug 2018
I15-Extreme Conditions	High-pressure/high-temperature phase diagram of zinc Daniel Errandonea , Simon Macleod , Javier Ruiz-Fuertes , L. Burakovsky , Malcolm Mcmahon , Craig Wilson , Jordi Ibañez , Dominik Daisenberger , Catalin Popescu Journal Of Physics: Condensed Matter DOI: 10.1088/1361-648X/aacac0 Diamond Proposal Number(s): [19846] Open Access Show Abstract ▼ Abstract: The phase diagram of zinc (Zn) has been explored up to 140 GPa and 6000 K, by combining optical observations, x-ray diffraction, and ab-initio calculations. In the pressure range covered by this study, Zn is found to retain a hexagonal close-packed (hcp) crystal symmetry up to the melting temperature. The known decrease of the axial ratio (c/a) of the hcp phase of Zn under compression is observed in x-ray diffraction experiments from 300 K up to the melting temperature. The pressure at which c/a reaches √3 (≈10 GPa) is not affected by temperature. When this ideal axial ratio is reached, we observed that single crystals of Zn, formed at high temperature, break into multiple poly-crystals. In addition, a noticeable change in the pressure dependence of c/a takes place at the same pressure. Both phenomena can be caused by an isomorphic second-order phase transition induced by pressure in Zn. The reported melt curve extends previous results from 24 to 135 GPa. The pressure dependence obtained for the melting temperature is accurately described by using a Simon–Glatzel equation. The determined melt curve agrees with previous low-pressure studies and with shock-wave experiments, with a melting temperature of 5060(30) K at 135 GPa. Finally, a thermal equation of state is reported, which at room-temperature agrees with the literature.	Jun 2018
	An ultrahigh CO2-loaded silicalite-1 zeolite: Structural stability and physical properties at high pressures and temperatures Tomas Marqueno , David Santamaria-Perez , Javier Ruiz-Fuertes , Raquel Chuliá-Jordán , Jose L. Jordá , Fernando Rey , Chris Mcguire , Abby Kavner , Simon Macleod , Dominik Daisenberger , Catalin Popescu , Placida Rodriguez-Hernandez , Alfonso Muñoz Inorganic Chemistry DOI: 10.1021/acs.inorgchem.8b00523 Show Abstract ▼ Abstract: We report the formation of an ultrahigh CO2-loaded pure-SiO2 silicalite-1 structure at high pressure (0.7 GPa) from the interaction of empty zeolite and fluid CO2 medium. The CO2-filled structure was characterized in situ by means of synchrotron powder X-ray diffraction. Rietveld refinements and Fourier recycling allowed the location of 16 guest carbon dioxide molecules per unit cell within the straight and sinusoidal channels of the porous framework to be analyzed. The complete filling of pores by CO2 molecules favors structural stability under compression, avoiding pressure-induced amorphization below 20 GPa, and significantly reduces the compressibility of the system compared to that of the parental empty one. The structure of CO2-loaded silicalite-1 was also monitored at high pressures and temperatures, and its thermal expansivity was estimated.	May 2018
	Structural evolution of CO2-filled pure silica LTA zeolite under high-pressure high-temperature conditions David Santamaria Perez , Tomas Marqueño , Simon Macleod , Javier Ruiz-Fuertes , Dominik Daisenberger , Raquel Chulia-Jordan , Daniel Errandonea , Jose Luis Jorda , Fernando Rey , Chris Mcguire , Adam Makhluf , Abby Kavner , Catalin Popescu Chemistry Of Materials DOI: 10.1021/acs.chemmater.7b01158 Show Abstract ▼ Abstract: The crystal structure of CO2-filled pure-SiO2 LTA zeolite has been studied at high pressures and temperatures using synchrotron-based x-ray powder diffraction. Its structure consists of 13 CO2 guest molecules, 12 of them accommodated in the large α-cages and 1 in the β-cages, giving a SiO2:CO2 stoichiometric ratio smaller than 2. The structure remains stable under pressure up to 20 GPa with a slight pressure-dependent rhombohedral distortion, indicating that pressure-induced amorphization is prevented by the insertion of guest species in this open framework. The ambient-temperature lattice compressibility has been determined. In situ high-pressure resistive-heating experiments up to 750 K allow us to estimate the thermal expansivity at P~5 GPa. Our data confirm that the insertion of CO2 reverses the negative thermal expansion of the empty zeolite structure. No evidence of any chemical reaction was observed. The possibility of synthesizing a silicon carbonate at high temperatures and higher pressures is discussed in terms of the evolution of C – O and Si – O distances between molecular and framework atoms.	May 2017

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