Preparation and electrical conductivity of (Zr, Hf, Pr, Y, La) O high entropy fluorite oxides

2022 ◽  
Vol 105 ◽  
pp. 122-130
Author(s):  
Fengnian Zhang ◽  
Fuhao Cheng ◽  
Chufei Cheng ◽  
Meng Guo ◽  
Yufeng Liu ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
High Entropy

scholarly journals Electrical and thermal transport behaviours of high-entropy perovskite thermoelectric oxides

2021 ◽  
Author(s):  
Yunpeng Zheng ◽  
Mingchu Zou ◽  
Wenyu Zhang ◽  
Di Yi ◽  
Jinle Lan ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
High Performance ◽  
Bulk Sample ◽  
Defect Engineering ◽  
High Entropy ◽  
Large Lattice ◽  
Thermoelectric Oxides ◽  
First Time ◽  
Mass Fluctuation

AbstractOxide-based ceramics could be promising thermoelectric materials because of their thermal and chemical stability at high temperature. However, their mediocre electrical conductivity or high thermal conductivity is still a challenge for the use in commercial devices. Here, we report significantly suppressed thermal conductivity in SrTiO3-based thermoelectric ceramics via high-entropy strategy for the first time, and optimized electrical conductivity by defect engineering. In high-entropy (Ca0.2Sr0.2Ba0.2Pb0.2La0.2)TiO3 bulks, the minimum thermal conductivity can be 1.17 W/(m·K) at 923 K, which should be ascribed to the large lattice distortion and the huge mass fluctuation effect. The power factor can reach about 295 μW/(m·K2) by inducing oxygen vacancies. Finally, the ZT value of 0.2 can be realized at 873 K in this bulk sample. This approach proposed a new concept of high entropy into thermoelectric oxides, which could be generalized for designing high-performance thermoelectric oxides with low thermal conductivity.

scholarly journals Thermal Stability of MoNbTaVW High Entropy Alloy Thin Films

Coatings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 941
Author(s):  
Ao Xia ◽  
Robert Franz
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Thermal Stability ◽  
Solid Solution ◽  
Electrical Conductivity ◽  
High Entropy Alloy ◽  
Solid Solution Phase ◽  
Body Centered Cubic ◽  
High Entropy ◽  
Thermal Stability Of

Refractory high entropy alloys are an interesting material class because of their high thermal stability, decent electrical conductivity, and promising mechanical properties at elevated temperature. In the present work, we report on the thermal stability of body-centered cubic MoNbTaVW solid solution thin films that were synthesized by cathodic arc deposition. After vacuum annealing up to 1600 °C, the morphology, chemical composition, crystal structure, and electrical conductivity, as well as the mechanical properties, were analyzed. The observed body-centered cubic MoNbTaVW solid solution phase is stable up to 1500 °C. The evolution of electrical and mechanical properties due to the annealing treatment is discussed based on the observed structural changes of the synthesized thin films.

scholarly journals Dielectric and electromagnetic interference shielding properties of high entropy (Zn,Fe,Ni,Mg,Cd)Fe2O4 ferrite

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Adrian Radoń ◽  
Łukasz Hawełek ◽  
Dariusz Łukowiec ◽  
Jerzy Kubacki ◽  
Patryk Włodarczyk
Keyword(s):  
Electrical Conductivity ◽  
Microwave Absorption ◽  
Electromagnetic Interference ◽  
Average Crystallite Size ◽  
Shielding Effectiveness ◽  
Absorption Properties ◽  
Ac Electrical Conductivity ◽  
Microwave Absorption Properties ◽  
High Entropy ◽  
Two Stages

AbstractThe new (Zn,Mg,Ni,Fe,Cd)Fe2O4 high entropy ferrite with average crystallite size 11.8 nm was synthesized in two stages by annealing of co-precipitated amorphous precursor. The dielectric spectroscopy confirms, that the electrical conductivity and polarization processes are associated with the mobility of electrons in the structure of ferrite. It was concluded, that the both, high frequency complex dielectric permittivity as well as complex magnetic permeability are strongly temperature and frequency dependent. The AC electrical conductivity is associated with quantum mechanical tunneling of electrons and related to the transfer of charge carriers between Fe2+ and Fe3+ ions. Moreover, the microwave absorption properties were determined. The best microwave absorption properties have been confirmed in the frequency range 1.9 to 2.1 GHz for a layer which is 0.8–1 cm thick. For this range, reflection loss (RL) is lower than −25 dB and shielding effectiveness (SE) lower than −50 dB.

Pressure effects on electronic structure and electrical conductivity of TiZrHfNb high-entropy alloy

2022 ◽  
Vol 140 ◽  
pp. 107394
Author(s):  
S.A. Uporov ◽  
R.E. Ryltsev ◽  
V.A. Sidorov ◽  
S. Kh Estemirova ◽  
E.V. Sterkhov ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Electronic Structure ◽  
Pressure Effects ◽  
High Entropy Alloy ◽  
High Entropy

Removing Substrate Background in TEM Microanalysis

1974 ◽  
Vol 32 ◽  
pp. 568-569
Author(s):  
John C. Russ ◽  
Nicholas C. Barbi
Keyword(s):  
Electrical Conductivity ◽  
Rapid Growth ◽  
Organic Film ◽  
Absolute Concentration ◽  
Background Signal ◽  
X Ray ◽  
Elemental Concentrations ◽  
Transmission Electron ◽  
Electron Microscopes ◽  
The Continuum

The rapid growth of interest in attaching energy-dispersive x-ray analysis systems to transmission electron microscopes has centered largely on microanalysis of biological specimens. These are frequently either embedded in plastic or supported by an organic film, which is of great importance as regards stability under the beam since it provides thermal and electrical conductivity from the specimen to the grid.Unfortunately, the supporting medium also produces continuum x-radiation or Bremsstrahlung, which is added to the x-ray spectrum from the sample. It is not difficult to separate the characteristic peaks from the elements in the specimen from the total continuum background, but sometimes it is also necessary to separate the continuum due to the sample from that due to the support. For instance, it is possible to compute relative elemental concentrations in the sample, without standards, based on the relative net characteristic elemental intensities without regard to background; but to calculate absolute concentration, it is necessary to use the background signal itself as a measure of the total excited specimen mass.

Macromolecular structures of biological specimens are not obscured by controlled osmium impregnation

1983 ◽  
Vol 41 ◽  
pp. 606-607
Author(s):  
Klaus-Ruediger Peters ◽  
Samuel A. Green
Keyword(s):  
Thin Films ◽  
Electrical Conductivity ◽  
Critical Point ◽  
Metal Films ◽  
High Magnification ◽  
Osmium Impregnation ◽  
Instrumental Resolution ◽  
20 Nm ◽  
Continuous Metal

High magnification imaging of macromolecules on metal coated biological specimens is limited only by wet preparation procedures since recently obtained instrumental resolution allows visualization of topographic structures as smal l as 1-2 nm. Details of such dimensions may be visualized if continuous metal films with a thickness of 2 nm or less are applied. Such thin films give sufficient contrast in TEM as well as in SEM (SE-I image mode). The requisite increase in electrical conductivity for SEM of biological specimens is achieved through the use of ligand mediated wet osmiuum impregnation of the specimen before critical point (CP) drying. A commonly used ligand is thiocarbohvdrazide (TCH), first introduced to TEM for en block staining of lipids and glvcomacromolecules with osmium black. Now TCH is also used for SEM. However, after ligand mediated osinification nonspecific osmium black precipitates were often found obscuring surface details with large diffuse aggregates or with dense particular deposits, 2-20 nm in size. Thus, only low magnification work was considered possible after TCH appl ication.

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