Room Temperature Gas Sensing Mechanism of SnO2 towards Chloroform: Comparing First Principles Calculations with Sensing Experiments

2021 ◽  
pp. 149603
Author(s):  
Ahmed A Abokifa ◽  
Kelsey Haddad ◽  
Baranidharan Raman ◽  
John Fortner ◽  
Pratim Biswas
Keyword(s):  
First Principles ◽  
Room Temperature ◽  
Gas Sensing ◽  
First Principles Calculations ◽  
Sensing Mechanism

scholarly journals A room-temperature ferroelectric semimetal

2019 ◽  
Vol 5 (7) ◽  
pp. eaax5080 ◽  
Author(s):  
Pankaj Sharma ◽  
Fei-Xiang Xiang ◽  
Ding-Fu Shao ◽  
Dawei Zhang ◽  
Evgeny Y. Tsymbal ◽  
...  
Keyword(s):  
First Principles ◽  
Electrical Transport ◽  
Room Temperature ◽  
Electric Polarization ◽  
First Principles Calculations ◽  
New Class ◽  
Weyl Semimetal ◽  
Ferroelectric Domain Structure ◽  
Ferroelectric Domains ◽  
Crystalline Metal

Coexistence of reversible polar distortions and metallicity leading to a ferroelectric metal, first suggested by Anderson and Blount in 1965, has so far remained elusive. Electrically switchable intrinsic electric polarization, together with the direct observation of ferroelectric domains, has not yet been realized in a bulk crystalline metal, although incomplete screening by mobile conduction charges should, in principle, be possible. Here, we provide evidence that native metallicity and ferroelectricity coexist in bulk crystalline van der Waals WTe2by means of electrical transport, nanoscale piezoresponse measurements, and first-principles calculations. We show that, despite being a Weyl semimetal, WTe2has switchable spontaneous polarization and a natural ferroelectric domain structure at room temperature. This new class of materials has tantalizing potential for functional nanoelectronics applications.

Where Should We Look For High Zt Materials: Suggestions From Theory.

2000 ◽  
Vol 626 ◽  
Author(s):  
M. Fornari ◽  
D. J. Singh ◽  
I. I. Mazin ◽  
J. L. Feldman
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
First Principles ◽  
Room Temperature ◽  
First Principles Calculations ◽  
High Electrical Conductivity ◽  
Bulk Materials ◽  
Low Thermal Conductivity ◽  
Computational Exploration ◽  
Single Material

ABSTRACTThe key challenges in discovering new high ZT thermoelectrics are understanding how the nearly contradictory requirements of high electrical conductivity, high thermopower and low thermal conductivity can be achieved in a single material and based on this identifying suitable compounds. First principles calculations provide a material specific microscopic window into the relevant properties and their origins. We illustrate the utility of the approach by presenting specific examples of compounds belonging to the class of skutterudites that are or are not good thermoelectrics along with the microscopic reasons. Based on our computational exploration we make a suggestion for achieving higher values of ZT at room temperature in bulk materials, namely n-type La(Ru,Rh)4Sb12 with high La-filling.

scholarly journals Phase Stability in U-6Nb Alloy Doped with Ti from the First Principles Theory

2020 ◽  
Vol 10 (10) ◽  
pp. 3417
Author(s):  
Alexander Landa ◽  
Per Söderlind ◽  
Amanda Wu
Keyword(s):  
Phase Stability ◽  
First Principles ◽  
Density Functional ◽  
Room Temperature ◽  
Rapid Quenching ◽  
Quantum Mechanical ◽  
First Principles Calculations ◽  
Functional Theory ◽  
The Density Functional Theory ◽  
Effect Of Impurities

First-principles calculations within the density-functional-theory (DFT) approach are conducted in order to explore and explain the effect of small amounts of titanium on phase stability in the U-6Nb alloy. During rapid quenching from high to room temperature, metastable phases α′ (orthorhombic), α″ (monoclinic), and γ0 (tetragonal) can form, depending on Nb concentration. Important mechanical properties depend on the crystal structure and, therefore, an understanding of the effect of impurities on phase stability is essential. Insights on this issue are obtained from quantum-mechanical DFT calculations. The DFT framework does not rely on any material-specific assumptions and is therefore ideal for an unbiased investigation of the U-Nb system.

Disparate strain response of the thermal transport properties of bilayer penta-graphene as compared to that of monolayer penta-graphene

2019 ◽  
Vol 21 (28) ◽  
pp. 15647-15655 ◽  
Author(s):  
Zhehao Sun ◽  
Kunpeng Yuan ◽  
Xiaoliang Zhang ◽  
Guangzhao Qin ◽  
Xiaojing Gong ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Transport Equation ◽  
First Principles ◽  
Room Temperature ◽  
Lattice Thermal Conductivity ◽  
Boltzmann Transport Equation ◽  
Strain Response ◽  
First Principles Calculations ◽  
Boltzmann Transport ◽  
Strain Modulation

In this study, strain modulation of the lattice thermal conductivity of monolayer and bilayer penta-graphene (PG) at room temperature was investigated using first-principles calculations combined with the phonon Boltzmann transport equation.

Reaction mechanism of metal and pyrite under HPHT conditions and improvement of the properties

2022 ◽  
Author(s):  
Yao Wang ◽  
Dan Xu ◽  
Shan Gao ◽  
Qi Chen ◽  
Dayi Zhou ◽  
...  
Keyword(s):  
Thermal Stability ◽  
High Pressure ◽  
Reaction Mechanism ◽  
First Principles ◽  
Room Temperature ◽  
First Principles Calculations ◽  
Mine Wastewater ◽  
Al Addition ◽  
Thermal Stability Of ◽  
Pyrite Tailings

Abstract Pyrite tailings are the main cause of acid mine wastewater. An idea was put forward to more effectively use pyrite, and it was modified by exploiting the reducibility of metal represented by Al under high-pressure and high-temperature (HPHT) conditions. Upon increasing the Al addition, the conductivity of pyrite were effectively improved, which is nearly 734-times higher than that of unmodified pyrite at room temperature. First-principles calculations were used to determine the influence of a high pressure on the pyrite lattice. The high pressure increased the thermal stability of pyrite, reduced pyrite to high-conductivity Fe7S8 (pyrrhotite) by Al, and prevented the formation of iron. Through hardness and density tests the influence of Al addition on the hardness and toughness of samples was explored. Finally the possibility of using other metal-reducing agents to improve the properties of pyrite was discussed.

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