RESISTIVE ANOMALIES AT NEAR 250 K IN Hg-Ca-Cu-O AND Fe-S SYSTEMS

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3755-3757
Author(s):  
S. S. YOM ◽  
JONG-KU PARK ◽  
G. H. KIM ◽  
H. S. KIM ◽  
J. Y. LEE ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Magnetic Susceptibility ◽  
Mechanical Alloying ◽  
Thermoelectric Power ◽  
Thermal Hysteresis ◽  
Unknown Origin ◽  
Synthesis Condition ◽  
Nominal Composition ◽  
Rapid Drop

High pressure synthesized samples of nominal composition of Ca 2-x Hg x CuO y with x=0.10~0.20 under reductive synthesis condition showed stable and reproducible resistivity onset transition at 225~254 K accompanied by rapid drop of thermoelectric power without accompanying magnetic susceptibility transition. Fe 1-x S ( x =0) by mechanical alloying method showed resistivity anomaly and thermal hysteresis at 150~180 K. These resistive anomalies may be phase transition of unknown origin rather than an indication of superconductivity.

Physical properties of electrically conducting and stable molecular neutral radical solid [Co(2,3-Nc)(CN)2]CH3CN (2,3-Nc = 2,3-naphthalocyanine)

2004 ◽  
Vol 08 (11) ◽  
pp. 1258-1268 ◽  
Author(s):  
Toshio Naito ◽  
Naoko Matsumura ◽  
Tamotsu Inabe ◽  
Masaki Matsuda ◽  
Hiroyuki Tajima
Keyword(s):  
Phase Transition ◽  
Magnetic Susceptibility ◽  
Physical Properties ◽  
Thermoelectric Power ◽  
Charge Separation ◽  
Energy Gap ◽  
Reflectance Spectra ◽  
Strongly Correlated ◽  
Neutral Radical ◽  
Type Transition

Solid state properties of dicyano(2,3-naphthalocyaninato)cobalt(III) neutral radical crystal, [ Co (2,3- Nc )( CN )2] CH 3 CN , were characterized by measurements of the resistivity under high pressure and under uniaxial strain, thermoelectric power, magnetic susceptibility, ESR and polarized reflectance spectra. The title compound exhibited thermally activated-type electrical conductivity along the c-axis. The room temperature (RT) resistivity ρRT along the c-axis and activation energy Ea rapidly decreased with increasing pressure. The temperature-dependent thermoelectric power S was that of a typical one-dimensional (1D) semiconductor. However the high absolute value of S suggested that this electronic system should be strongly correlated. Although the electrical resistivity exhibited monotonous temperature-dependence, the magnetic susceptibility clearly indicated a Peierls-type transition and marked fluctuation from RT. Both Peierls-type transitions and fluctuations are characteristic phenomena to 1D conductors. Furthermore ESR spectra manifested that the Peierls-type transition occurred at 100 K. The inconsistency between the electrical behavior (without a phase-transition) and magnetic behavior (with a phase-transition) indicates separation of the degrees of freedom in spin and charge (spin-charge separation) of this material. Spin-charge separation is a theoretically predicted phenomenon peculiar to the 1D conductors with strong correlation. The reflectance spectra were quantitatively explained by a 1D Hubbard model, and manifested the existence of a structural fluctuation of this material from RT. Based on these observed physical properties it is concluded that [ Co (2,3- Nc )( CN )2] CH 3 CN is a strongly correlated 1D semiconductor with a Mott(Hubbard) type energy gap and characterised with a fluctuation and spin-charge separation.

A phase transition in Ga2Se3 under high pressure

1994 ◽  
Vol 72 (9-10) ◽  
pp. 681-682 ◽  
Author(s):  
K. V. Savchenko ◽  
V. V. Shchennikov
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Thermoelectric Power ◽  
Electrical Resistance ◽  
Room Temperature ◽  
Vickers Microhardness ◽  
Zinc Blende ◽  
Stockbarger Method ◽  
Zinc Blende Structure ◽  
Semiconductor Type

Ga2Se3 crystals with an excess of Se were grown by the Bridgman–Stockbarger method and had a defect zinc blende structure with a0 = 5.42 Å [Formula: see text] (1 Å = 10−10 m). At room temperature the resistivity was equal to (4.5 ± 1.5) × 1011 Ω cm, the thermoelectric power was (−1.1 ± 0.1) mV K−1 and the Vickers microhardness was (357 ± 9) kg mm−2. The gamma-induced conductivity was measured in the gamma-emitting power range of 3–340 rad s−1. Pressure dependencies of electrical resistance and thermoelectric power at room temperature allowed us to determine a phase transition of the semiconductor–semiconductor type at 14.2 GPa.

Pressure Tuning of Crystalline As2Te3

2004 ◽  
Vol 848 ◽  
Author(s):  
T. J. Scheidemantel ◽  
J. F. Meng ◽  
J. V. Badding
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Thermoelectric Power ◽  
Diamond Anvil Cell ◽  
Ambient Pressure ◽  
Structural Phase ◽  
Absolute Value ◽  
Pressure Tuning ◽  
Diamond Anvil ◽  
Pressure Phase

ABSTRACTWe report the pressure dependence of the thermoelectric power of As2Te3. Pressures up to 10 GPa were induced using a Mao-Bell diamond anvil cell. The absolute value of the thermoelectric power dropped from S ≈ 230μV/K at ambient pressure to S ≈ 75 GPa near 5 GPa. At 6 GPa it then increased rapidly to S ≈ 220βV/K. This behavior is indicative of a structural phase transition as suggested by previously published high pressure phase diagrams.

Cyclone Bomb hits Southern Brazil in 2020

2020 ◽  
Vol 3 (3) ◽  
Author(s):  
Ricardo Gobato ◽  
Alireza Heidari
Keyword(s):  
High Pressure ◽  
Atmospheric Pressure ◽  
High Speed ◽  
Satellite Images ◽  
The State ◽  
Southern Brazil ◽  
Santa Catarina ◽  
High Area ◽  
South Of Brazil ◽  
Rapid Drop

An “explosive extratropical cyclone” is an atmospheric phenomenon that occurs when there is a very rapid drop in central atmospheric pressure. This phenomenon, with its characteristic of rapidly lowering the pressure in its interior, generates very intense winds and for this reason it is called explosive cyclone, bomb cyclone. With gusts recorded of 116 km/h, atmospheric phenomenon – “cyclone bomb” (CB) hit southern Brazil on June 30, the beginning of winter 2020, causing destruction in its influence over. One of the cities most affected was Chapecó, west of the state of Santa Catarina. The satellite images show that the CB generated a low pressure (976 mbar) inside it, generating two atmospheric currents that moved at high speed. In a northwest-southeast direction, Bolivia and Paraguay, crossing the states of Parana and Santa Catarina, and this draft that hit the south of Brazil, which caused the destruction of the affected states.  Another moving to Argentina, southwest-northeast direction, due to high area of high pressure (1022 mbar). Both enhanced the phenomenon.

Electrical Resistivity, Magnetic Susceptibility and Thermoelectric Power of PtGa2

1990 ◽  
Author(s):  
Li-Shing Hsu ◽  
Lu-Wei Zhou ◽  
F. L. Machado ◽  
W. G. Clark ◽  
R. S. Williams
Keyword(s):  
Electrical Resistivity ◽  
Magnetic Susceptibility ◽  
Thermoelectric Power

scholarly journals Orpiment under compression: metavalent bonding at high pressure

2020 ◽  
Vol 22 (6) ◽  
pp. 3352-3369 ◽  
Author(s):  
Vanesa Paula Cuenca-Gotor ◽  
Juan Ángel Sans ◽  
Oscar Gomis ◽  
Andres Mujica ◽  
Silvana Radescu ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Strong Change ◽  
Isostructural Phase Transition

Orpiment (α-As2S3) under compression reports a strong change in the coordination of As atoms at 25 GPa, which can be ascribed to an isostructural phase transition. These changes are consistent with the formation of metavalent bonds in orpiment.

scholarly journals Crystal and electronic structure engineering of tin monoxide by external pressure

2021 ◽  
Author(s):  
Kun Li ◽  
Junjie Wang ◽  
Vladislav A. Blatov ◽  
Yutong Gong ◽  
Naoto Umezawa ◽  
...  
Keyword(s):  
Phase Transition ◽  
High Pressure ◽  
Band Gap ◽  
High Pressures ◽  
Low Pressure ◽  
Widespread Application ◽  
Space Group ◽  
Tin Monoxide ◽  
High Possibility ◽  
Pressure Phase

AbstractAlthough tin monoxide (SnO) is an interesting compound due to its p-type conductivity, a widespread application of SnO has been limited by its narrow band gap of 0.7 eV. In this work, we theoretically investigate the structural and electronic properties of several SnO phases under high pressures through employing van der Waals (vdW) functionals. Our calculations reveal that a metastable SnO (β-SnO), which possesses space group P21/c and a wide band gap of 1.9 eV, is more stable than α-SnO at pressures higher than 80 GPa. Moreover, a stable (space group P2/c) and a metastable (space group Pnma) phases of SnO appear at pressures higher than 120 GPa. Energy and topological analyses show that P2/c-SnO has a high possibility to directly transform to β-SnO at around 120 GPa. Our work also reveals that β-SnO is a necessary intermediate state between high-pressure phase Pnma-SnO and low-pressure phase α-SnO for the phase transition path Pnma-SnO →β-SnO → α-SnO. Two phase transition analyses indicate that there is a high possibility to synthesize β-SnO under high-pressure conditions and have it remain stable under normal pressure. Finally, our study reveals that the conductive property of β-SnO can be engineered in a low-pressure range (0–9 GPa) through a semiconductor-to-metal transition, while maintaining transparency in the visible light range.

scholarly journals Single Crystal Growth and Physical Properties of Pyroxene CoGeO3

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 378
Author(s):  
Li Zhao ◽  
Zhiwei Hu ◽  
Hanjie Guo ◽  
Christoph Geibel ◽  
Hong-Ji Lin ◽  
...  
Keyword(s):  
High Pressure ◽  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Crystal Growth ◽  
Physical Properties ◽  
Single Crystal ◽  
Single Crystals ◽  
Magnetic Moments ◽  
Single Crystal Growth ◽  
The Impact

We report on the synthesis and physical properties of cm-sized CoGeO3 single crystals grown in a high pressure mirror furnace at pressures of 80 bar. Direction dependent magnetic susceptibility measurements on our single crystals reveal highly anisotropic magnetic properties that we attribute to the impact of strong single ion anisotropy appearing in this system with TN∼33.5 K. Furthermore, we observe effective magnetic moments that are exceeding the spin only values of the Co ions, which reveals the presence of sizable orbital moments in CoGeO3.

Sign in / Sign up

Export Citation Format

Share Document