Pressure-induced boron clathrates with ambient-pressure superconductivity

2021 ◽  
Vol 9 (39) ◽  
pp. 13782-13788
Author(s):  
Yiwei Liang ◽  
Meiling Xu ◽  
Shuyi Lin ◽  
Xuanhao Yuan ◽  
Ziyang Qu ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Current Result ◽  
Low Pressures

A pressure-induced boron clathrate LaB8 structure exhibits potential superconductivity of 20 K at ambient pressure. This current result provides a new route to find high-Tc cage superconductors at low-pressures.

scholarly journals Evidence for a pressure-induced antiferromagnetic quantum critical point in intermediate-valence UTe2

2020 ◽  
Vol 6 (42) ◽  
pp. eabc8709 ◽  
Author(s):  
S. M. Thomas ◽  
F. B. Santos ◽  
M. H. Christensen ◽  
T. Asaba ◽  
F. Ronning ◽  
...  
Keyword(s):  
Ambient Pressure ◽  
Applied Pressure ◽  
Quantum Critical Point ◽  
Antiferromagnetic Order ◽  
Intermediate Valence ◽  
Ac Calorimetry ◽  
Unconventional Superconductor ◽  
Spin Triplet ◽  
Magnetic States ◽  
Low Pressures

UTe2 is a recently discovered unconventional superconductor that has attracted much interest because of its potentially spin-triplet topological superconductivity. Our ac calorimetry, electrical resistivity, and x-ray absorption study of UTe2 under applied pressure reveals key insights on the superconducting and magnetic states surrounding pressure-induced quantum criticality at Pc1 = 1.3 GPa. First, our specific heat data at low pressures, combined with a phenomenological model, show that pressure alters the balance between two closely competing superconducting orders. Second, near 1.5 GPa, we detect two bulk transitions that trigger changes in the resistivity, which are consistent with antiferromagnetic order, rather than ferromagnetism. Third, the emergence of magnetism is accompanied by an increase in valence toward a U4+ (5f2) state, which indicates that UTe2 exhibits intermediate valence at ambient pressure. Our results suggest that antiferromagnetic fluctuations may play a more substantial role on the superconducting state of UTe2 than previously thought.

The Use of Tris(Trimethylsilyl)Arsine to Deposit GaAs by OMCVD

1990 ◽  
Vol 204 ◽  
Author(s):  
Alan D. Berry ◽  
Andrew P. Purdy ◽  
Richard L. Wells ◽  
James W. Pasterczyk ◽  
James D. Johansen ◽  
...  
Keyword(s):  
Chemical Vapor Deposition ◽  
Vapor Deposition ◽  
Electron Spectroscopy ◽  
Auger Electron ◽  
Ambient Pressure ◽  
Chemical Vapor ◽  
X Ray Diffraction ◽  
X Ray ◽  
Gaas Substrates ◽  
Low Pressures

ABSTRACTChemical vapor deposition experiments using (Me3Si)3As with either GaCl3 or Me3Ga at ambient pressure have produced films of GaAs on Si and semi-conducting GaAs substrates. The films have been characterized by X-ray diffraction and Auger electron spectroscopy, and each have small amounts of C and O impurities. No desired films were deposited from (C6F5)3GaAs(SiMe3)3 at 500°C and low pressures.

scholarly journals Concept for a MEMS-type vacuum sensor based on electrical conductivity measurements

2017 ◽  
Vol 6 (2) ◽  
pp. 367-374 ◽  
Author(s):  
Friederike Julia Giebel ◽  
Marcel Köhle ◽  
Till Stramm ◽  
Klaus T. Kallis ◽  
Horst L. Fiedler
Keyword(s):  
Electrical Conductivity ◽  
Ambient Pressure ◽  
Electrical Characterization ◽  
Sensor Chip ◽  
Simple Type ◽  
Vacuum Sensor ◽  
Reference Measurements ◽  
Gas Volume ◽  
Low Pressures

Abstract. The concept of the micro-structured vacuum sensor presented in this article is the measurement of the electrical conductivity of thinned gases in order to develop a small, economical and quite a simple type of vacuum sensor. There are already some approaches for small vacuum sensors. Most of them are based on conservative measurement principles similar to those used in macroscopic vacuum gauges. Ionization gauges use additional sources of energy, like hot cathodes, ultraviolet radiation or high voltage for example, for ionizing gas molecules and thereby increasing the number of charge carriers for measuring low pressures. In contrast, the concept discussed here cannot be found in macroscopic sensor systems because it depends on the microscopic dimension of a gas volume defined by two electrodes. Here we present the concept and the production of a micro-structured vacuum sensor chip, followed by the electrical characterization. Reference measurements with electrodes at a distance of about 1 mm showed currents in the size of picoampere and a conductivity depending on ambient pressure. In comparison with these preliminary measurements, fundamental differences regarding pressure dependence of the conductivity are monitored in the electrical characterization of the micro-structured sensor chip. Finally the future perspectives of this sensor concept are discussed.

Environmental microscopy of capillary stress-induced strain behavior in ambient-pressure aerogels

1996 ◽  
Vol 54 ◽  
pp. 850-851
Author(s):  
Sudeep M. Rao ◽  
Joshua Samuel ◽  
Sai S. Prakash ◽  
C. Jeffrey Brinker
Keyword(s):  
Silica Aerogel ◽  
Ambient Pressure ◽  
Drying Shrinkage ◽  
Pore Filling ◽  
Silica Network ◽  
Strain Behavior ◽  
Partially Saturated ◽  
Capillary Stress ◽  
Wetting Liquid ◽  
Aerogel Films

Ambient pressure silica aerogel thin films have recently been prepared by exploiting reversible drying shrinkage caused by derivatization of the internal gel surface. Aerogels have porosities of upto 99.9% and due to the small size of the pores (few nanometers), large capillary stresses are produced in gels that are partially saturated with a wetting liquid. As a result of these capillary stresses, the flexible silica network undergoes strain which has been observed using environmental microscopy. This technique allows variation of the equilibrium vapor pressure and temperature, and a simultaneous monitoring of the deformation of the unconstrained film thickness. We have observed >600% deformation during the pore-filling and pore-emptying cycles. In this presentation, we discuss the unique stress-strain behavior of these films.Ref.: Sai S. Prakash, C. Jeffrey Brinker, Alan J. Hurd & Sudeep M. Rao, "Silica aerogel films prepared at ambient pressure by using surface derivatization to induce reversible drying shrinkage", Nature. Vol. 374, 30 March, 1995, 439-443.

ON MAGNETIC PROPERTIES 0F (TMTSF)2PF6AT AMBIENT PRESSURE

1983 ◽  
Vol 44 (C3) ◽  
pp. C3-1001-C3-1005
Author(s):  
S. Iwabuchi ◽  
H. Fukuyama
Keyword(s):  
Magnetic Properties ◽  
Ambient Pressure

NEAR-WALL CHARACTERISTICS OF AN IMPINGING GASOLINE SPRAY AT INCREASED AMBIENT PRESSURE AND WALL TEMPERATURE

2009 ◽  
Vol 19 (11) ◽  
pp. 997-1012 ◽  
Author(s):  
Jochen Stratmann ◽  
D. Martin ◽  
P. Unterlechner ◽  
R. Kneer
Keyword(s):  
Wall Temperature ◽  
Ambient Pressure ◽  
Near Wall

Effect of ambient pressure on low-density nozzle plumes

1995 ◽  
Author(s):  
Chan-Hong Chung ◽  
Kenneth D ◽  
Robert Stubbs
Keyword(s):  
Ambient Pressure ◽  
Low Density

Influence of intramolecular interactions on carbon dioxide gas adsorption capacity in Mesoporous Imine polymers

2018 ◽  
Author(s):  
Jaya Prakash Madda ◽  
Pilli Govindaiah ◽  
Sushant Kumar Jena ◽  
Sabbhavat Krishna ◽  
Rupak Kishor
Keyword(s):  
Carbon Dioxide ◽  
Adsorption Capacity ◽  
Density Functional ◽  
Gas Adsorption ◽  
Ambient Pressure ◽  
Condensation Reaction ◽  
Intramolecular Interactions ◽  
Carbon Dioxide Adsorption ◽  
Nitrogen Gas ◽  
Adsorption Characteristic

<p>Covalent organic Imine polymers with intrinsic meso-porosity were synthesized by condensation reaction between 4,4-diamino diphenyl methane and (para/meta/ortho)-phthaladehyde. Even though these polymers were synthesized from precursors of bis-bis covalent link mode, the bulk materials were micrometer size particles with intrinsic mesoporous enables nitrogen as well as carbon dioxide adsorption in the void spaces. These polymers were showed stability up to 260<sup>o</sup> centigrade. Nitrogen gas adsorption capacity up to 250 cc/g in the ambient pressure was observed with type III adsorption characteristic nature. Carbon dioxide adsorption experiments reveal the possible terminal amine functional group to carbamate with CO<sub>2</sub> gas molecule to the polymers. One of the imine polymers, COP-3 showed more carbon dioxide sorption capacity and isosteric heat of adsorption (Q<sub>st</sub>) than COP-1 and COP-2 at 273 K even though COP-3 had lower porosity for nitrogen gas than COP-1 and COP-2. We explained the trends in gas adsorption capacities and Qst values as a consequence of the intra molecular interactions confirmed by Density Functional Theory computational experiments on small molecular fragments.</p>

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