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Instruments / Technical Area	Publication Details	Published
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 CO 2 -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
I15-Extreme Conditions	Structural and electrical study of the topological insulator SnBi2Te4 at high pressure R. Vilaplana , Juan Angel Sans Tresserras , F.j. Manjón , A. Andrada-chacón , J. Sánchez-benítez , Catalin Popescu , Oscar Gomis , André Luis De Jesus Pereira , Braulio Garcia Domene , P. Rodríguez-hernández , A. Muñoz , Dominik Daisenberger , O. Oeckler Journal Of Alloys And Compounds 685, 962 - 970 DOI: 10.1016/j.jallcom.2016.06.170 Diamond Proposal Number(s): [9102] Show Abstract ▼ Abstract: We report high-pressure X-ray diffraction and electrical measurements of the topological insulator SnBi2Te4 at room temperature. The pressure dependence of the structural properties of the most stable phase of SnBi2Te4 at ambient conditions (trigonal phase) have been experimentally determined and compared with results of our ab initio calculations. Furthermore, a comparison of SnBi2Te4 with the parent compound Bi2Te3 shows that the central TeSnTe trilayer, which substitutes the Te layer at the center of the TeBiTeBiTe layers of Bi2Te3, plays a minor role in the compression of SnBi2Te4. Similar to Bi2Te3, our resistance measurements and electronic band structure simulations in SnBi2Te4 at high pressure suggest that this compound exhibits a pressure-induced electronic topological transition or Lifshitz transition between 3.5 and 5.0 GPa.	Nov 2016
I15-Extreme Conditions	Compressibility Systematics of Calcite-Type Borates: An Experimental and Theoretical Structural Study on ABO3 (A = Al, Sc, Fe, and In) David Santamaría-pérez , Oscar Gomis , Juan Angel Sans Tresserras , Henry. M. Ortiz , Ángel Vegas , Daniel Errandonea , Javier Ruiz-fuertes , Domingo Martinez-garcia , Braulio Garcia-domene , André Luis De Jesus Pereira , Francisco Javier Manjón , Placida Rodríguez-hernández , Alfonso Muñoz , Fabio Piccinelli , Marco Bettinelli , Catalin Popescu The Journal Of Physical Chemistry C 118 (8), 4354 - 4361 DOI: 10.1021/jp4124259 Show Abstract ▼ Abstract: The structural properties of calcite-type orthoborates ABO3 (A = Al, Fe, Sc, and In) have been investigated at high pressures up to 32 GPa. They were studied experimentally using synchrotron powder X-ray diffraction and theoretically by means of ab initio total-energy calculations. We found that the calcite-type structure remains stable up to the highest pressure explored in the four studied compounds. Experimental and calculated static geometries (unit-cell parameters and internal coordinates), bulk moduli, and their pressure derivatives are in good agreement. The compressibility along the c axis is roughly three times that along the a axis. Our data clearly indicate that the compressibility of borates is dominated by that of the [AO6] octahedral group and depends on the size of the trivalent A cations. An analysis of the relationship between isomorphic borates and carbonates is also presented, which points to the potentiality of considering borates as chemical analogues of the carbonate mineral family.	Feb 2014

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