Phase stability and electronic structure of iridium metal at the megabar range

[EN] The 5d transition metals have attracted specific interest for high-pressure studies due to their extraordinary stability and intriguing electronic properties. In particular, iridium metal has been proposed to exhibit a recently discovered pressure-induced electronic transition, the so-called core-level crossing transition at the lowest pressure among all the 5d transition metals. Here, we report an experimental structural characterization of iridium by x-ray probes sensitive to both long- and short-range order in matter. Synchrotron-based powder x-ray diffraction results highlight a large stability range (up to 1.4 Mbar) of the low-pressure phase. The compressibility behaviour was characterized by an accurate determination of the pressure-volume equation of state, with a bulk modulus of 339(3) GPa and its derivative of 5.3(1). X-ray absorption spectroscopy, which probes the local structure and the empty density of electronic states above the Fermi level, was also utilized. The remarkable agreement observed between experimental and calculated spectra validates the reliability of theoretical predictions of the pressure dependence of the electronic structure of iridium in the studied interval of compressions.The authors thank the financial support of the Spanish Ministry of Science, Innovation and Universities, the Spanish Research Agency (AEI), the European Fund for Regional Development (FEDER) under Grant No. MAT2016-75586-C4-1/2-P and the Generalitat Valenciana under Grant Prometeo/2018/123 (EFIMAT). V. M. acknowledges the Juan de la Cierva fellowship (FJCI-2016-27921) and J.A.S. acknowledges the Ramón y Cajal fellowship program (RYC-2015-17482) and Spanish Mineco Project FIS2017-83295-P. We acknowledge the European Synchrotron Radiation Facility for provision of official research beamtimes, the Swedish Government Strategic Research Area in Materials Science on Functional Materials at Linköping University (Faculty Grant SFO-Mat-LiU No 2009 00971), Knut and Alice Wallenbergs Foundation Project Strong Field Physics and New States of Matter CoTXS (2014 2019). The interpretation of theoretical results was supported by the Ministry of Science and High Education of the Russian Federation in the framework of Increase Competitiveness Program of NUST MISIS (No. K2-2019-001) implemented by a governmental decree dated 16 March 2013, No 211.Monteseguro, V.; Sans-Tresserras, JÁ.; Cuartero, V.; Cova, F.; Abrikosov, I.; Olovsson, W.; Popescu, C.... (2019). Phase stability and electronic structure of iridium metal at the megabar range. Scientific Reports. 9:1-9. https://doi.org/10.1038/s41598-019-45401-xS199Cynn, H., Klepeis, J. E., Yoo, C.-S. & Young, D. A. Osmium has the Lowest Experimentally Determined Compressibility. Phys. Rev. Lett. 88, 135701–135704 (2002).Döhring, T. et al. Prototyping iridium coated mirrors for x-ray astronomy. Proc. SPIE 10235, 1023504–1023511 (2017).Bednorz, J. G. & Müller, K. A. Possible high Tc superconductivity in the Ba−La−Cu−O system. Z. Phys. B: Condens. Matter 64, 189–193 (1986).Tokura, Y. & Nagaosa, N. Orbital Physics in Transition-Metal Oxides. Science 288, 462–468 (2000).Kobayashi, K.-I., Kimura, T., Sawada, H., Terakura, K. & Tokura, Y. Room-temperature magnetoresistance in an oxide material with an ordered double-perovskite structure. Nature (London) 395, 677–680 (1998).Hrubiak, R., Meng, Y. & Shen, G. Microstructures define melting of molybdenum at high pressures. Nature Commun. 8, 14562–14571 (2017).Cerenius, Y. & Dubrovinsky, L. Compressibility measurements on iridium. J. Alloys Compd. 306, 26–29 (2000).Grussendorff, S., Chetty, N. & Dreysse, H. Theoretical studies of iridium under pressure. J. Phys. Condens. Matter 15, 4127–4134 (2003).Burakovsky, L. et al. Ab initio phase diagram of iridium. Phys. Rev. B 94, 094112–094120 (2016).Dubrovinsky, L. et al. The most incompressible metal osmium at static pressures above 750 gigapascals. Nature 525, 226–229 (2015).Tal, A. A. et al. Pressure-induced crossing of the core levels in 5d metals. Phys. Rev. B 93, 205150–205156 (2016).Merkel, S. et al. Deformation of polycrystalline MgO at pressures of the lower mantle. J Geophys Res. 107, 2271–2287 (2002).Greenberg, E. et al. Pressure-Induced Site-Selective Mott Insulator-Metal Transition in Fe2O3. Phys. Rev. X 8, 031059–031071 (2018).Nemoshkalenko, V. V., Mil’man, V. Y., Zhalko-Titarenko, A. V., Antonov, V. N. & Shitikov, Y. L. Pis’ma Zh. Eksp Teor. Fiz 47, 295–297 (1988).Rehr, J. J. & Albers, R. C. Theoretical approaches to x-ray absorption fine structure. Rev. Mod. Phys. 72, 621–654 (2000).Poiarkova, A. V. & Rehr, J. J. Multiple-scattering x-ray-absorption fine-structure Debye-Waller factor calculations. Phys. Rev. B 59, 948–957 (1998).Glazyrin, K. et al. Importance of correlation effects in hcp iron revealed by a pressure-induced electronic topological transition. Phys. Rev. Lett. 110, 117206–117210 (2013).Sham, T. K. L-edge x-ray-absorption systematics of the noble metals Rh, Pd, and Ag and the main-group metals In and Sn: A study of the unoccupied density of states in 4d elements. Phys. Rev. B 31, 1888–1902 (1985).Leapman, R. D., Grunes, L. A. & Fejes, P. L. Study of the L23 edges in the 3d transition metals and their oxides by electron-energy-loss spectroscopy with comparisons to theory. Phys. Rev. B 26, 614–635 (1982).Choy, J.-H., Kim, D.-K., Hwang, S.-H., Demazeau, G. & Jung, D.-Y. the Ir-O Bond Covalency in Ionic Iridium Perovskites. J. Am. Chem. Soc. 117, 8557–8566 (1995).Clancy, J. P. et al. Spin-orbit coupling in iridium-based 5d compounds probed by x-ray absorption spectroscopy. Phys. Rev. B 86, 195131- (2012).Snigirev, A., Kohn, V., Snigireva, I. & Lengeler, B. A compound refractive lens for focusing high-energy X-rays. Nature 384, 49–51 (1996).Dewaele, A., Loubeyre, P. & Mezouar, M. Equations of state of six metals above 94 GPa. Phys. Rev. B 70, 094112–094119 (2004).Prescher, C. & Prakapenka, V. B. DIOPTAS: a program for reduction of twodimensional X-ray diffraction data and data exploration. High Pressure Res. 35, 223–230 (2015).Toby, B. H. & Von Dreele, R. B. GSAS-II: the genesis of a modern open-source all-purpose crystallography software package. J. Appl. Cryst. 46(2), 544–549 (2013).Birch, F. Finite strain isotherm and velocities for single‐crystal and polycrystalline NaCl at high pressures and 300 K. J. Geophys. Res. 83, 1257–1268 (1978).Angel, R. J., González-Platas, J. & Alvaro, M. EosFit7c and a Fortran module (library) for equation of state calculations. Z. Kristallogr. 229, 405–419 (2014).Mathon, O. et al. The time-resolved and extreme conditions XAS (TEXAS) facility at the European Synchrotron Radiation Facility: the general-purpose EXAFS bending-magnet beamline BM23. J. Synchrotron Radiat. 22, 1548–1554 (2015).Ohfuji, H. et al. "Natural occurrence of pure nano-polycrystalline diamond from impact crater". Scientific Reports. 5: 14702.s, L. D., 2000. J. Alloys Compd. 306, 26–29 (2015).Ravel, B. & Newville, M. ATHENA, ARTEMIS, HEPHAESTUS: data analysis for X-ray absorption spectroscopy using IFEFFIT. J. Synchrotron Radiat. 12, 537–577 (2005).Blaha, P., Schwarz, K., Madsen, G. K. H., Kvasnicka, D. & Luitz, J. WIEN2K, An Augmented Plane Wave + Local Orbitals Program for Calculating Crystal Properties. Karlheinz Schwarz, Techn. Universität, Wien, Austria. (2001).Perdew, J. P., Burke, S. & Ernzerhof, M. Generalized Gradient Approximation Made Simple. Phys. Rev. Lett. 77, 3865–3868 (1996)

Complementary hydro-mechanical coupled finite/discrete element and microseismic modelling to predict hydraulic fracture propagation in tight shale reservoirs

This paper presents a novel approach to predict the propagation of hydraulic fractures in tight shale reservoirs. Many hydraulic fracture modelling schemes assume that the fracture direction is pre-seeded in the problem domain discretization. This is a severe limitation as the reservoir often contains large numbers of pre-existing fractures that strongly influence the direction of the propagating fracture. To circumvent these shortcomings a new fracture modelling treatment is proposed where the introduction of discrete fracture surfaces is based on new and dynamically updated geometrical entities rather than the topology of the underlying spatial discretization. Hydraulic fracturing is an inherently coupled engineering problem with interactions between fluid flow and fracturing when the stress state of the reservoir rock attains a failure criterion. This work follows a staggered hydro-mechanical coupled finite/discrete element approach to capture the key interplay between fluid pressure and fracture growth. In field practice the fracture growth is hidden from the design engineer and microseismicity is often used to infer hydraulic fracture lengths and directions. Microsesimic output can also be computed from changes of the effective stress in the geomechanical model and compared against field microseismicity. A number of hydraulic fracture numerical examples are presented to illustrate the new technology

Origin of magnetic frustrations in Fe-Ni Invar alloys

Contains fulltext : 32823.pdf (publisher's version ) (Open Access