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21.
Sebastian Vogel Dr. Dominik Baumann Robin Niklaus Dr. Elena Bykova Dr. Maxim Bykov Prof. Dr. Natalia Dubrovinskaia Prof. Dr. Leonid Dubrovinsky Prof. Dr. Wolfgang Schnick 《Angewandte Chemie (International ed. in English)》2018,57(22):6691-6695
Phosphorus oxonitride (PON) is isoelectronic with SiO2 and may exhibit a similar broad spectrum of intriguing properties as silica. However, PON has only been sparsely investigated under high‐pressure conditions and there has been no evidence on a PON polymorph with a coordination number of P greater than 4. Herein, we report a post‐coesite (pc) PON polymorph exhibiting a stishovite‐related structure with P in a (5+1) coordination. The pc‐PON was synthesized using the multianvil technique and characterized by powder X‐ray diffraction, solid‐state NMR spectroscopy, TEM measurements and in situ synchrotron X‐ray diffraction in diamond anvil cells. The structure model was verified by single‐crystal X‐ray diffraction at 1.8 GPa and the isothermal bulk modulus of pc‐PON was determined to K0=163(2) GPa. Moreover, an orthorhombic PON polymorph (o‐PON) was observed under high‐pressure conditions and corroborated as the stable modification at pressures above 17 GPa by DFT calculations. 相似文献
22.
Leonid S. Dubrovinsky Natalia A. Dubrovinskaia Vitaly B. Prokopenko Tristan Le Bihan 《高压研究》2013,33(2):495-499
The full profile refinement of the structure of the calcium-ferrite type NaAlSiO 4 was carried out at pressures up to 40 GPa. This high-pressure modification of NaAlSiO 4 is known to be stable at least to 75 GPa and 2450 K that corresponds to a middle part of the Earth's lower mantle. A zero-pressure unit cell volume V 0 =36.58(2) cm 3 /mol was obtained from a sample synthesized from natural albite. In situ pressure-volume data (with found V 0 ) was fitted to the Birch-Murnaghan equation of state, and it yielded the bulk modulus equal to 220(1) GPa and its pressure derivative equal to 4.1(1). 相似文献
23.
L. S. Dubrovinsky N. A. Dubrovinskaia V. Prakapenka F. Seifert F. Langenhorst V. Dmitriev 《高压研究》2013,33(1-2):35-39
We synthesised a number of new silica modifications in the electrically heated diamond anvil cells at pressures over 100 GPa and temperatures over 1200 K. The structure of these polymorphs is based on hexagonal close packing of oxygen atoms with different degree of ordering of silicon atoms in octahedral and tetrahedral sites. 相似文献
24.
Dubrovinskaia N Dubrovinsky L Kantor I Crichton WA Dmitriev V Prakapenka V Shen G Vitos L Ahuja R Johansson B Abrikosov IA 《Physical review letters》2005,95(24):245502
Iron and magnesium are almost immiscible at ambient pressure. The low solubility of Mg in Fe is due to a very large size mismatch between the alloy components. However, the compressibility of Mg is much higher than that of Fe, and therefore the difference in atomic sizes between elements decreases dramatically with pressure. Based on the predictions of ab initio calculations, we demonstrate in a series of experiments in a multianvil apparatus and in electrically and laser-heated diamond anvil cells that high pressure promotes solubility of magnesium in iron. At the megabar pressure range, more than 10 at. % of Mg can dissolve in Fe and then the alloy can be quenched to ambient conditions. A generality of the concept of high-pressure alloying between immiscible elements is demonstrated by its application to two other Fe group elements, Co and Ni. 相似文献
25.
Dubrovinsky L Dubrovinskaia N Abrikosov IA Vennström M Westman F Carlson S van Schilfgaarde M Johansson B 《Physical review letters》2001,86(21):4851-4854
We have measured the pressure-volume (P-V) relations for cubic iron-nickel alloys for three different compositions: Fe 0.64Ni (0.36), Fe 0.55Ni (0.45), and Fe 0.20Ni (0.80). It is observed that for a certain pressure range the bulk modulus does not change or can even decrease to some minimum value, after which it begins to increase under still higher pressure. In our experiment, we observe for the first time a new effect, namely, that the Fe-Ni alloys with high Ni concentrations, which show positive thermal expansion at ambient pressure, become Invar system upon compression over a certain pressure range. 相似文献
26.
Dubrovinsky L Dubrovinskaia N Crichton WA Mikhaylushkin AS Simak SI Abrikosov IA de Almeida JS Ahuja R Luo W Johansson B 《Physical review letters》2007,98(4):045503
In a series of experiments in externally electrically heated diamond anvil cells we demonstrate that at pressures above approximately 240 GPa gold adopts a hexagonal-close-packed structure. Ab initio calculations predict that at pressures about 250 GPa different stacking sequences of close-packed atomic layers in gold become virtually degenerate in energy, strongly supporting the experimental observations. 相似文献
27.
Andrey Aslandukov Pascal L. Jurzick Dr. Maxim Bykov Alena Aslandukova Dr. Artem Chanyshev Dr. Dominique Laniel Dr. Yuqing Yin Fariia I. Akbar Dr. Saiana Khandarkhaeva Dr. Timofey Fedotenko Dr. Konstantin Glazyrin Dr. Stella Chariton Prof. Vitali Prakapenka Dr. Fabrice Wilhelm Dr. Andrei Rogalev Dr. Davide Comboni Dr. Michael Hanfland Prof. Natalia Dubrovinskaia Prof. Leonid Dubrovinsky 《Angewandte Chemie (International ed. in English)》2023,62(47):e202311516
A series of isostructural Ln3O2(CN3) (Ln=La, Eu, Gd, Tb, Ho, Yb) oxoguanidinates was synthesized under high-pressure (25–54 GPa) high-temperature (2000–3000 K) conditions in laser-heated diamond anvil cells. The crystal structure of this novel class of compounds was determined via synchrotron single-crystal X-ray diffraction (SCXRD) as well as corroborated by X-ray absorption near edge structure (XANES) measurements and density functional theory (DFT) calculations. The Ln3O2(CN3) solids are composed of the hitherto unknown CN35− guanidinate anion—deprotonated guanidine. Changes in unit cell volumes and compressibility of Ln3O2(CN3) (Ln=La, Eu, Gd, Tb, Ho, Yb) compounds are found to be dictated by the lanthanide contraction phenomenon. Decompression experiments show that Ln3O2(CN3) compounds are recoverable to ambient conditions. The stabilization of the CN35− guanidinate anion at ambient conditions provides new opportunities in inorganic and organic synthetic chemistry. 相似文献