scholarly journals Superconductivity up to 243 K in the yttrium-hydrogen system under high pressure

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Panpan Kong ◽  
Vasily S. Minkov ◽  
Mikhail A. Kuzovnikov ◽  
Alexander P. Drozdov ◽  
Stanislav P. Besedin ◽  
...  
Keyword(s):  
High Pressure ◽  
Theoretical Calculations ◽  
Hydrogen System ◽  
Diamond Anvil ◽  
Magnetic Transport ◽  
Binary Compounds ◽  
Yttrium Hydride ◽  
Room Temperature Superconductivity ◽  
Isotopic Effects ◽  
Comprehensive Study

AbstractThe discovery of superconducting H3S with a critical temperature Tc∼200 K opened a door to room temperature superconductivity and stimulated further extensive studies of hydrogen-rich compounds stabilized by high pressure. Here, we report a comprehensive study of the yttrium-hydrogen system with the highest predicted Tcs among binary compounds and discuss the contradictions between different theoretical calculations and experimental data. We synthesized yttrium hydrides with the compositions of YH3, YH4, YH6 and YH9 in a diamond anvil cell and studied their crystal structures, electrical and magnetic transport properties, and isotopic effects. We found superconductivity in the Im-3m YH6 and P63/mmc YH9 phases with maximal Tcs of ∼220 K at 183 GPa and ∼243 K at 201 GPa, respectively. Fm-3m YH10 with the highest predicted Tc > 300 K was not observed in our experiments, and instead, YH9 was found to be the hydrogen-richest yttrium hydride in the studied pressure and temperature range up to record 410 GPa and 2250 K.

scholarly journals Helical Molecular Springs under High Pressure

2021 ◽  
Author(s):  
Jiaxu Liang ◽  
Cheng-Wei Ju ◽  
Wenhao Zheng ◽  
Manfred Wagner ◽  
Zijie Qiu ◽  
...  
Keyword(s):  
High Pressure ◽  
Hydrostatic Pressure ◽  
Diamond Anvil Cell ◽  
Theoretical Calculations ◽  
Molecular Machines ◽  
Structure Property ◽  
Fluorescent Properties ◽  
Structure Property Relationships ◽  
Diamond Anvil ◽  
Molecular Springs

Although the unique structure of helicenes resembles molecular springs, the effects of pressure on their extension–contraction cycles have rarely been explored. Herein, we investigated the fluorescence of two π-extended [n]helicenes with different helical lengths n, here named [7] and [9], under high pressure in a diamond anvil cell. Based on experimental results and theoretical calculations, the mechanical and fluorescent properties of the molecular springs were found to be influenced not only by the intermolecular packing, but also by the intramolecular π-π interactions between their overlapping helixes. As a more rigid molecular spring, [9] exhibited a more sensitive response of its fluorescence to hydrostatic pressure than [7]. Our results provide new insights into structure-property relationships under high-pressure conditions and verify the potential of helicenes as molecular springs for future applications in molecular machines.

High-pressure structural phase transition and metallization in Ga2S3 under non-hydrostatic and hydrostatic conditions up to 36.4 GPa

2021 ◽  
Author(s):  
Linfei Yang ◽  
Jianjun Jiang ◽  
Lidong Dai ◽  
Haiying Hu ◽  
Meiling Hong ◽  
...  
Keyword(s):  
Phase Transition ◽  
Raman Spectroscopy ◽  
High Pressure ◽  
Structural Properties ◽  
Structural Phase Transition ◽  
First Principles ◽  
Theoretical Calculations ◽  
Structural Phase

The vibrational, electrical and structural properties of Ga2S3 were explored by Raman spectroscopy, EC measurements, HRTEM and First-principles theoretical calculations under different pressure environments up to 36.4 GPa.

scholarly journals Phase transitions beyond post-perovskite in NaMgF3 to 160 GPa

2019 ◽  
Vol 116 (39) ◽  
pp. 19324-19329 ◽  
Author(s):  
Rajkrishna Dutta ◽  
Eran Greenberg ◽  
Vitali B. Prakapenka ◽  
Thomas S. Duffy
Keyword(s):  
Phase Transitions ◽  
Diamond Anvil Cell ◽  
Extrasolar Planets ◽  
High Pressures ◽  
Model System ◽  
Similar Sequence ◽  
Deep Interior ◽  
Diamond Anvil ◽  
Binary Compounds ◽  
Pressure Phase

Neighborite, NaMgF3, is used as a model system for understanding phase transitions in ABX3 systems (e.g., MgSiO3) at high pressures. Here we report diamond anvil cell experiments that identify the following phases in NaMgF3 with compression to 162 GPa: NaMgF3 (perovskite) → NaMgF3 (post-perovskite) → NaMgF3 (Sb2S3-type) → NaF (B2-type) + NaMg2F5 (P21/c) → NaF (B2) + MgF2 (cotunnite-type). Our results demonstrate the existence of an Sb2S3-type post-post-perovskite ABX3 phase. We also experimentally demonstrate the formation of the P21/c AB2X5 phase which has been proposed theoretically to be a common high-pressure phase in ABX3 systems. Our study provides an experimental observation of the full sequence of phase transitions from perovskite to post-perovskite to post-post-perovskite followed by 2-stage breakdown to binary compounds. Notably, a similar sequence of transitions is predicted to occur in MgSiO3 at ultrahigh pressures, where it has implications for the mineralogy and dynamics in the deep interior of large, rocky extrasolar planets.

scholarly journals The thermal conductivity of the Earth's core and implications for its thermal and compositional evolution

2020 ◽  
Author(s):  
Kenji Ohta ◽  
Kei Hirose
Keyword(s):  
Thermal Conductivity ◽  
High Pressure ◽  
Thermal History ◽  
Diamond Anvil Cell ◽  
High Pressures ◽  
Iron Alloys ◽  
Compositional Evolution ◽  
The Earth ◽  
Diamond Anvil ◽  
High Pressures And Temperatures

Abstract Precise determinations of the thermal conductivity of iron alloys at high pressures and temperatures are essential for understanding the thermal history and dynamics of the metallic cores of the Earth. We review relevant high-pressure experiments using a diamond-anvil cell and discuss implications of high core conductivity for its thermal and compositional evolution.

scholarly journals Aluminate Red Phosphor in Light-Emitting Diodes: Theoretical Calculations, Charge Varieties, and High-Pressure Luminescence Analysis

2017 ◽  
Vol 9 (28) ◽  
pp. 23995-24004 ◽  
Author(s):  
Niumiao Zhang ◽  
Yi-Ting Tsai ◽  
Mu-Huai Fang ◽  
Chong-Geng Ma ◽  
Agata Lazarowska ◽  
...  
Keyword(s):  
High Pressure ◽  
Light Emitting Diodes ◽  
Theoretical Calculations ◽  
Luminescence Analysis ◽  
Red Phosphor ◽  
Light Emitting

scholarly journals Theoretical calculations for solid oxygen under high pressure

2008 ◽  
Vol 20 (33) ◽  
pp. 335219 ◽  
Author(s):  
Kazuki Nozawa ◽  
Nobuyuki Shima ◽  
Kenji Makoshi
Keyword(s):  
High Pressure ◽  
Theoretical Calculations ◽  
Solid Oxygen

PHASE TRANSITION IN LAYERED PEROVSKITE LIKE MANGANATE Ca3Mn2O7 UNDER HIGH PRESSURE

2001 ◽  
Vol 15 (18) ◽  
pp. 2491-2497 ◽  
Author(s):  
J. L. ZHU ◽  
L. C. CHEN ◽  
R. C. YU ◽  
F. Y. LI ◽  
J. LIU ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
Diamond Anvil Cell ◽  
The Other ◽  
Layered Perovskite ◽  
X Ray Diffraction ◽  
Two Phase ◽  
X Ray ◽  
Diamond Anvil

In situ high pressure energy dispersive X-ray diffraction measurements on layered perovskite-like manganate Ca 3 Mn 2 O 7 under pressures up to 35 GPa have been performed by using diamond anvil cell with synchrotron radiation. The results show that the structure of layered perovskite-like manganate Ca 3 Mn 2 O 7 is unstable under pressure due to the easy compression of NaCl-type blocks. The structure of Ca 3 Mn 2 O 7 underwent two phase transitions under pressures in the range of 0~35 GPa. One was at about 1.3 GPa with the crystal structure changing from tetragonal to orthorhombic. The other was at about 9.5 GPa with the crystal structure changing from orthorhombic back to another tetragonal.

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