Search

The anhydrous pyrocarbonate and the first hydrogen pyrocarbonate Li[HC2O5] have been synthesized in a laser‐heated diamond anvil cell at moderate pressures (≈25 ${ \approx 25}$ GPa). The structures of the two compounds have been obtained from single crystal X‐ray diffraction data. Raman spectroscopy and DFT calculations have been employed to further characterize their structure‐property relations. The present results significantly enlarge the group of inorganic pyrocarbonates by the discovery of the hydrogenated pyrocarbonate anion Li[HC2O5]−. In the structure of Li[HC2O5] there is a symmetric O−H−O arrangement at high pressures, which converts to a conventional O−H⋯ ${ \cdots }$ O hydrogen bond upon pressure release. [ABSTRACT FROM AUTHOR]

The anhydrous pyrocarbonate and the first hydrogen pyrocarbonate Li[HC2O5] have been synthesized in a laser‐heated diamond anvil cell at moderate pressures (≈25 ${ \approx 25}$ GPa). The structures of the two compounds have been obtained from single crystal X‐ray diffraction data. Raman spectroscopy and DFT calculations have been employed to further characterize their structure‐property relations. The present results significantly enlarge the group of inorganic pyrocarbonates by the discovery of the hydrogenated pyrocarbonate anion Li[HC2O5]−. In the structure of Li[HC2O5] there is a symmetric O−H−O arrangement at high pressures, which converts to a conventional O−H⋯ ${ \cdots }$ O hydrogen bond upon pressure release. [ABSTRACT FROM AUTHOR]

While polymeric carbon monoxide (pCO) has been experimentally found to remain amorphous and undecomposed at room temperature up to 50 GPa, the question of whether crystalline counterparts of it can be obtained naturally raises. From different computational studies, it can be inferred that either the crystallization of amorphous pCO (a-pCO) or its decomposition into a mixture of CxOy suboxides (x > y) or carbon and CO2 may occur. In this study, we report experimental investigations of the high temperature (700–4000 K) transformation of a-pCO in the 47–120 GPa pressure range, conducted by x-ray diffraction in laser heated diamond anvil cells. Our results show the formation of no crystalline phases other than CO2 phase V, thus indicating the decomposition of the pristine a-pCO into CO2 and, likely, a mixture of amorphous CxOy suboxides and amorphous carbon hardly detectable at extreme conditions. These results support the theoretical picture of the pCO decomposition. We also show that the pressure-temperature kinetic border for this decomposition is very steep, thus indicating a strongly pressure-dependent kinetic barrier. [ABSTRACT FROM AUTHOR]

Understanding the fate of subducted carbonates is a prerequisite for the elucidation of the Earth's deep carbon cycle. Here we show that the concomitant presence of Ca[CO3] with CO2 in a subducting slab very likely results in the formation of an anhydrous mixed pyrocarbonate, Ca 3 C 2 O 5 2 CO 3 , at moderate pressure (≈ 20 GPa) and temperature (≈ 1500 K) conditions. We show that at these conditions Ca 3 C 2 O 5 2 CO 3 can be obtained by reacting Ca[CO3] with CO2 in a laser-heated diamond anvil cell. The crystal structure was obtained from synchrotron-based single crystal X-ray diffraction data. Density Functional Perturbation Theory calculations in combination with experimental Raman spectroscopy results unambiguously confirmed the structural model. The crystal structure of Ca 3 C 2 O 5 2 CO 3 is characterized by the presence of CO 3 2 − - and C 2 O 5 2 − -groups. The results presented here imply that the formation of Ca 3 C 2 O 5 2 CO 3 needs to be taken into account when constructing models of the deep carbon cycle of the Earth. Carbonates are transported into the deep Earth by subduction of the oceanic lithosphere, but the stability fields of subducted carbonates as a function of pressure, temperature, and composition remain incompletely described. Here, the authors synthesize the anhydrous, mixed pyrocarbonate Ca3[C2O5]2[CO3] from Ca[CO3] and CO2 in a laser-heated diamond anvil cell at moderate pressure and elucidate its structural features. [ABSTRACT FROM AUTHOR]

In this overview article, we present the main features of the upgraded ID27 beamline which is fully optimised to match the exceptional characteristics of the new Extremely Bright Source (EBS) of the European Synchrotron Radiation Facility (ESRF). The ID27 beamline has been converted to a 120-m-long instrument and has undergone a major refurbishment of all its critical components including both hardware and software environments. We will successively introduce the ID27 undulator X-ray source, optical scheme and the main components of the experimental hutch. We will illustrate the potential of this new instrument through some selected research examples. [ABSTRACT FROM AUTHOR]

We present, in this overview article, the main features of the ID15B beamline on the new ESRF Extremely Bright Source (EBS). The ID15B beamline was fully reconstructed in 2015, considering the new capabilities of the future EBS machine. We will introduce the ID15 project, the ID15B undulator X-ray source, the optical scheme and the experimental hutch. The beamline ID15B is mostly dedicated to the determination of structural properties of solids at high pressure using angle-dispersive diffraction with diamond anvil cells. We present different selected research examples illustrating the capabilities of this instrument. [ABSTRACT FROM AUTHOR]

A chemical reaction between Sb and N2 was induced under high‐pressure (32–35 GPa) and high‐temperature (1600–2200 K) conditions, generated by a laser heated diamond anvil cell. The reaction product was identified by single crystal synchrotron X‐ray diffraction at 35 GPa and room temperature as crystalline antimony nitride with Sb3N5 stoichiometry and structure belonging to orthorhombic space group Cmc21. Only Sb−N bonds are present in the covalent bonding framework, with two types of Sb atoms respectively forming SbN6 distorted octahedra and trigonal prisms and three types of N atoms forming NSb4 distorted tetrahedra and NSb3 trigonal pyramids. Taking into account two longer Sb−N distances, the SbN6 trigonal prisms can be depicted as SbN8 square antiprisms and the NSb3 trigonal pyramids as NSb4 distorted tetrahedra. The Sb3N5 structure can be described as an ordered stacking in the bc plane of bi‐ layers of SbN6 octahedra alternated to monolayers of SbN6 trigonal prisms (SbN8 square antiprisms). The discovery of Sb3N5 finally represents the long sought‐after experimental evidence for Sb to form a crystalline nitride, providing new insights about fundamental aspects of pnictogens chemistry and opening new perspectives for the high‐pressure chemistry of pnictogen nitrides and the synthesis of an entire class of new materials. [ABSTRACT FROM AUTHOR]

A chemical reaction between Sb and N2 was induced under high‐pressure (32–35 GPa) and high‐temperature (1600–2200 K) conditions, generated by a laser heated diamond anvil cell. The reaction product was identified by single crystal synchrotron X‐ray diffraction at 35 GPa and room temperature as crystalline antimony nitride with Sb3N5 stoichiometry and structure belonging to orthorhombic space group Cmc21. Only Sb−N bonds are present in the covalent bonding framework, with two types of Sb atoms respectively forming SbN6 distorted octahedra and trigonal prisms and three types of N atoms forming NSb4 distorted tetrahedra and NSb3 trigonal pyramids. Taking into account two longer Sb−N distances, the SbN6 trigonal prisms can be depicted as SbN8 square antiprisms and the NSb3 trigonal pyramids as NSb4 distorted tetrahedra. The Sb3N5 structure can be described as an ordered stacking in the bc plane of bi‐ layers of SbN6 octahedra alternated to monolayers of SbN6 trigonal prisms (SbN8 square antiprisms). The discovery of Sb3N5 finally represents the long sought‐after experimental evidence for Sb to form a crystalline nitride, providing new insights about fundamental aspects of pnictogens chemistry and opening new perspectives for the high‐pressure chemistry of pnictogen nitrides and the synthesis of an entire class of new materials. [ABSTRACT FROM AUTHOR]

The elements hydrogen, carbon, and nitrogen are among the most abundant in the solar system. Still, little is known about the ternary compounds these elements can form under the high‐pressure and high‐temperature conditions found in the outer planets' interiors. These materials are also of significant research interest since they are predicted to feature many desirable properties such as high thermal conductivity and hardness due to strong covalent bonding networks. In this study, the high‐pressure high‐temperature reaction behavior of malononitrile H2C(CN)2, dicyandiamide (H2N)2C=NCN, and melamine (C3N3)(NH2)3 was investigated in laser‐heated diamond anvil cells. Two previously unknown compounds, namely α‐C(NH)2 and β‐C(NH)2, have been synthesized and found to have fully sp3‐hybridized carbon atoms. α‐C(NH)2 crystallizes in a distorted β‐cristobalite structure, while β‐C(NH)2 is built from previously unknown imide‐bridged 2,4,6,8,9,10‐hexaazaadamantane units, which form two independent interpenetrating diamond‐like networks. Their stability domains and compressibility were studied, for which supporting density functional theory calculations were performed. [ABSTRACT FROM AUTHOR]

The stabilization of nitrogen‐rich phases presents a significant chemical challenge due to the inherent stability of the dinitrogen molecule. This stabilization can be achieved by utilizing strong covalent bonds in complex anions with carbon, such as cyanide CN− and NCN2− carbodiimide, while more nitrogen‐rich carbonitrides are hitherto unknown. Following a rational chemical design approach, we synthesized antimony guanidinate SbCN3 at pressures of 32–38 GPa using various synthetic routes in laser‐heated diamond anvil cells. SbCN3, which is isostructural to calcite CaCO3, can be recovered under ambient conditions. Its structure contains the previously elusive guanidinate anion [CN3]5−, marking a fundamental milestone in carbonitride chemistry. The crystal structure of SbCN3 was solved and refined from synchrotron single‐crystal X‐ray diffraction data and was fully corroborated by theoretical calculations, which also predict that SbCN3 has a direct band gap with the value of 2.20 eV. This study opens a straightforward route to the entire new family of inorganic nitridocarbonates. [ABSTRACT FROM AUTHOR]

The stabilization of nitrogen‐rich phases presents a significant chemical challenge due to the inherent stability of the dinitrogen molecule. This stabilization can be achieved by utilizing strong covalent bonds in complex anions with carbon, such as cyanide CN− and NCN2− carbodiimide, while more nitrogen‐rich carbonitrides are hitherto unknown. Following a rational chemical design approach, we synthesized antimony guanidinate SbCN3 at pressures of 32–38 GPa using various synthetic routes in laser‐heated diamond anvil cells. SbCN3, which is isostructural to calcite CaCO3, can be recovered under ambient conditions. Its structure contains the previously elusive guanidinate anion [CN3]5−, marking a fundamental milestone in carbonitride chemistry. The crystal structure of SbCN3 was solved and refined from synchrotron single‐crystal X‐ray diffraction data and was fully corroborated by theoretical calculations, which also predict that SbCN3 has a direct band gap with the value of 2.20 eV. This study opens a straightforward route to the entire new family of inorganic nitridocarbonates. [ABSTRACT FROM AUTHOR]

The article discusses the field of science under extreme conditions of pressure and temperature, which encompasses various areas of research such as condensed-matter physics, Earth and planetary science, material synthesis and characterization, and biology. The ESRF Extremely Brilliant Source (ESRF-EBS), a high-energy fourth-generation synchrotron, is highlighted as a significant advancement in this field. The ESRF offers a range of beamlines that provide X-ray techniques for high-pressure studies, including diffraction, imaging, and probing of atomic arrangements and electronic and thermal excitations. The article also mentions the implementation of a high-power laser facility and a dynamic compression platform at specific beamlines. Overall, the article aims to provide an overview of the activities and capabilities of the ESRF under extreme conditions. [Extracted from the article]