Electrical conduction mechanism in films of Se80−xTe20Bix (0 ≤ x ≤ 12) glassy alloys

2019 ◽  
Vol 97 (2) ◽  
pp. 222-226 ◽  
Author(s):  
Deepika ◽  
Hukum Singh
Keyword(s):  
Electrical Conductivity ◽  
Physical Vapor Deposition ◽  
Conduction Mechanism ◽  
Charge Carriers ◽  
X Ray Diffraction ◽  
Glassy Alloys ◽  
Transmission Electron ◽  
Physical Vapor Deposition Method ◽  
Temperature Ranges ◽  
Lower Temperature

This paper reports the study of DC electrical conductivity of films of Se80−xTe20Bix (0 ≤ x ≤ 12) glasses prepared using physical vapor deposition method. The films were structurally characterized using X-ray diffraction (XRD) and transmission electron microscopy (TEM). TEM results indicate the formation of nanorods within the films. The electrical conductivity of the samples was studied using Keithley electrometer in the temperature range 303–373 K. The results show that conduction in these samples takes place via thermally assisted tunnelling and variable range hopping of charge carriers corresponding to higher and lower temperature ranges, respectively. Further, it was found that the conductivity increases with increase in Bi concentration in Se–Te system. This has been explained on the basis of chemically ordered network model. It was also found that nanorod formation improves the electrical conductivity of Se–Te–Bi system compared to bulk Se–Te–Bi system.

Synthesis and thermodynamic evaluation of intermetallic Mg-Ni/Mg-Cu nanoscale powders

2009 ◽  
Vol 24 (8) ◽  
pp. 2503-2510 ◽  
Author(s):  
Jun-Peng Lei ◽  
Xing-Long Dong ◽  
Fu-Guo Zhao ◽  
Hao Huang ◽  
Xue-Feng Zhang ◽  
...  
Keyword(s):  
Physical Vapor Deposition ◽  
Arc Discharge ◽  
Heat Of Formation ◽  
Thermodynamic Evaluation ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Physical Vapor Deposition Method ◽  
Effective Heat Of Formation ◽  
Good Agreement

Nanometer-sized intermetallic Mg-Ni and Mg-Cu compound powders were prepared by a physical vapor deposition method (arc discharge) and characterized by means of x-ray diffraction and transmission electron microscopy. Based on an empirical specific heat equation, the effective heat of formation and its temperature dependence were calculated to explain phase formation in nanoscale powders of the binary Mg-Ni and Mg-Cu systems. It is shown that theoretic calculations are in good agreement with the experimental observations.

Electrical Conduction in Trivalent Chromium and Nickel Molybdate

1987 ◽  
Vol 42 (11) ◽  
pp. 1257-1260 ◽  
Author(s):  
Kanchan Gaur ◽  
H. B. Lai
Keyword(s):  
Phase Transition ◽  
Electrical Conductivity ◽  
Conduction Mechanism ◽  
Trivalent Chromium ◽  
Charge Carriers ◽  
Energy Band Gap ◽  
Nickel Molybdate ◽  
Simplifying Assumptions ◽  
Temperature Ranges ◽  
Band Type

The electrical conductivity (σ) and Seebeck coefficient (S ) of trivalent chromium and nickel molybdate are measured at 500 -1200 K. On the basis of these data it is concluded that chromium molybdate undergoes a phase transition at 780 K and nickel molybdate at 740 K. log σ and S depend linearly on T-1 in certain temperature ranges. It is shown that the conduction mechanism in these solids is essentially of the band type in which the O2-:2p band is the valence band and M3+:4 s (transition metal 4 s band) the conduction band. Under simplifying assumptions the energy band gap and the mobility of the charge carriers are evaluated.

Microstructural Features of EB-PVD Thermal Barrier Coatings Irradiated by High-Intensity Pulsed Ion Beam

2008 ◽  
Vol 373-374 ◽  
pp. 300-303 ◽  
Author(s):  
C. Liu ◽  
X.G. Han ◽  
X.P. Zhu ◽  
M.K. Lei
Keyword(s):  
Electron Microscope ◽  
Thermal Barrier Coatings ◽  
High Intensity ◽  
Physical Vapor Deposition ◽  
Ion Beam ◽  
Thermal Barrier ◽  
X Ray Diffraction ◽  
Barrier Coatings ◽  
Transmission Electron ◽  
Single Column

Thermal barrier coatings (TBCs) fabricated by electron-beam physical-vapor deposition (EB-PVD) were irradiated by high-intensity pulsed ion beam (HIPIB) at an ion current density of 100 A/cm2 with a shot number of 1-10. Microstructural features of the irradiated EB-PVD TBCs were characterized by using X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. All the HIPIB-irradiated EB-PVD TBC surfaces present smooth and densified features. The originated intercolumnar channels growing out to the top-coat surface and nanometer-scale gaps inside each single column were sealed after the remelting of TBC surface induced by HIPIB, resulting in formation of a continuous remelted layer about 1-2 μm in thickness. The dense remelted layer can work as a barrier against the heat-flow and corrosive gases, and gives the possibility of improving thermal conductivity and oxidation resistance of the HIPIB irradiated EB-PVD TBC.

scholarly journals Effect of Tb-doped Concentration Variation on the Electrical and Dielectric Properties of CaF2 Nanoparticles

Nanomaterials ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 532 ◽  
Author(s):  
Xiaoyan Cui ◽  
Tingjing Hu ◽  
Jingshu Wang ◽  
Xin Zhong ◽  
Yinzhu Chen ◽  
...  
Keyword(s):  
Impedance Measurement ◽  
Transference Number ◽  
Potential Scattering ◽  
Charge Carriers ◽  
Ion Diffusion ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Transportation Process ◽  
Electron Transportation ◽  
Electrical And Dielectric Properties

Calcium fluoride (CaF2) nanoparticles with various terbium (Tb) doping concentrations were investigated by X-ray diffraction (XRD), transmission electron microscopy (TEM), and alternating current (AC) impedance measurement. The original shape and structure of CaF2 nanoparticles were retained after doping. In all the samples, the dominant charge carriers were electrons, and the F− ion transference number increased with increasing Tb concentration. The defects in the grain region considerably contributed to the electron transportation process. When the Tb concentration was less than 3%, the effect of the ionic radius variation dominated and led to the diffusion of the F− ions and facilitated electron transportation. When the Tb concentration was greater than 3%, the increasing deformation potential scattering dominated, impeding F− ion diffusion and electron transportation. The substitution of Ca2+ by Tb3+ enables the electron and ion hopping in CaF2 nanocrystals, resulting in increased permittivity.

scholarly journals An Efficient and Novel Ammonia Sensor Based on Polypyrrole/Tin Oxide/MWCNT Nanocomposite

2020 ◽  
Vol 32 (6) ◽  
pp. 1505-1510
Author(s):  
Ahmad Husain ◽  
Mohd Urooj Shariq ◽  
Anees Ahmad
Keyword(s):  
Electron Microscopy ◽  
Tin Oxide ◽  
Charge Carriers ◽  
Morphological Properties ◽  
X Ray Diffraction ◽  
Ammonia Sensing ◽  
Transmission Electron ◽  
Ft Ir ◽  
Ft Ir Spectroscopy

In present study, the synthesis and characterization of a novel polypyrrole (PPy)/tin oxide (SnO2)/MWCNT nanocomposite along with pristine polypyrrole is reported. These materials have been studied for their structural and morphological properties by FT-IR spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques. PPy/SnO2/MWCNT nanocomposite has been converted into a pellet-shaped sensor, and its ammonia sensing studies were carried out by calculating the variation in the DC electrical conductivity at different concentration of ammonia ranging from 10 to 1500 ppm. The sensing response of the sensor was determined at 1500, 1000, 500, 200, 100 and 10 ppm and found to be 70.4, 66.1, 62.2, 55.4, 50.8 and 39.7%, respectively The sensor showed a complete reversibility at lower concentrations along with excellent selectivity and stability. Finally, a sensing mechanism was also proposed involving polarons (charge carriers) of polypyrrole and lone pairs of ammonia molecules

Effect of Aging Treatment on Damping Capacity in Mncunife Alloy

2012 ◽  
Vol 246-247 ◽  
pp. 1158-1162
Author(s):  
Xu Fu ◽  
Ning Li ◽  
Yu Hua Wen ◽  
Jing Teng ◽  
Ying Zhang
Keyword(s):  
Electron Microscope ◽  
Aging Treatment ◽  
Damping Capacity ◽  
Torsion Pendulum ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Higher Temperature ◽  
Lower Temperature ◽  
The Relationship

M2052 alloys with various aging treatments are obtained in order to investigate the relationship between aging treatment and damping capacity by the torsion pendulum, X-Ray Diffraction (XRD) and Transmission Electron Microscope (TEM) methods. The results show that M2052 can obtain high damping capacity (δ>0.2) when aged at a range from 400°C to 450°C, and the damping capacity after aged at a lower temperature is higher than that aged at a higher temperature for the maximum values. TEM and XRD results show that fcc-fct transformation occurs after aging treatment. The volumes of fct structures are one of reason to affect the damping capacity in M2052 alloy. The better understanding aging treatment could promote the applications of M2052 alloy.

scholarly journals Fully soluble self-doped poly(3,4-ethylenedioxythiophene) with an electrical conductivity greater than 1000 S cm−1

2019 ◽  
Vol 5 (4) ◽  
pp. eaav9492 ◽  
Author(s):  
Hirokazu Yano ◽  
Kazuki Kudo ◽  
Kazumasa Marumo ◽  
Hidenori Okuzaki
Keyword(s):  
Electrical Conductivity ◽  
Critical Parameter ◽  
Colloidal Particles ◽  
Average Distance ◽  
Charge Carriers ◽  
High Electrical Conductivity ◽  
X Ray Diffraction ◽  
X Ray ◽  
Atomic Force ◽  
Technical Issues

Wet-processable and highly conductive polymers are promising candidates for key materials in organic electronics. Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) is commercially available as a water dispersion of colloidal particles but has some technical issues with PSS. Here, we developed a novel fully soluble self-doped PEDOT (S-PEDOT) with an electrical conductivity as high as 1089 S cm−1without additives (solvent effect). Our results indicate that the molecular weight of S-PEDOT is the critical parameter for increasing the number of nanocrystals, corresponding to the S-PEDOT crystallites evaluated by x-ray diffraction and conductive atomic force microscopic analyses as having high electrical conductivity, which reduced both the average distance between adjacent nanocrystals and the activation energy for the hopping of charge carriers, leading to the highest bulk conductivity.

scholarly journals Influence of Intercalation-Exfoliation-Reduction Technique towards the Physico-Chemical of VPO Catalysts

2013 ◽  
Vol 2013 ◽  
pp. 1-8
Author(s):  
Y. C. Wong ◽  
Y. H. Taufiq-Yap
Keyword(s):  
Electron Microscope ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vpo Catalysts ◽  
Transmission Electron ◽  
Physico Chemical ◽  
Vpo Catalyst ◽  
Temperature Programmed ◽  
Lower Temperature ◽  
Synthesized Materials

Four VPO catalysts were synthesized through intercalation and exfoliation in various alcohols and subsequent reduction of the exfoliated VOPO4sheets with various alcohols to produce VOHPO4⋅0.5H2O. The resulting VOHPO4⋅0.5H2O that undergoes the intercalation-exfoliation-reduction (IER) process will be further activated into VPO catalysts, and addition of 1 mole % Bi(NO3)3⋅5H2O in the first stage of this experiment has also being investigated. The synthesized materials were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and temperature-programmed reduction (TPR) in H2. Catalytic evaluation of the IER-treated and Bi-doped VPO catalysts was also studied on microreactor. The VPO catalyst produced through IER using 2-butanol and ethanol with addition of Bi, IERC(2Bu-Et)RBi1, gave the highest MA selectivity due to reactive O2−species released from the additional crystalline V5+phase formed by doping 1% bismuth as promoter (O2−-V5+pair) at relative lower temperature. Nevertheless, the VPO catalyst produced through IER using isobutanol, IERC(isoBu), gave the highest activity due to high amount of reactive O−species released from V4+phase (O−-V4+pair) whereby the IERC(isoBu) catalyst synthesized consists of high percentage of V4+(93 %).

Sol–gel synthesis, structural and electrical properties of Li2CoSiO4 cathode material

2014 ◽  
Vol 07 (06) ◽  
pp. 1440001 ◽  
Author(s):  
Michał Świętosławski ◽  
Marcin Molenda ◽  
Piotr Natkański ◽  
Piotr Kuśtrowski ◽  
Roman Dziembaj ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Sol Gel ◽  
Lithium Ion ◽  
X Ray Diffraction ◽  
X Ray ◽  
Transmission Electron ◽  
Structural And Electrical Properties ◽  
Potential Alternative ◽  
Sol Gel Synthesis ◽  
First Time

Polyanionic cathode materials for lithium-ion batteries start to be considered as potential alternative for layered oxide materials. Among them, Li 2 CoSiO 4, characterized by outstanding capacity and working voltage, seems to be an interesting substitute for LiFePO 4 and related systems. In this work, structural and electrical investigations of Li 2 CoSiO 4 obtained by sol–gel synthesis were presented. Thermal decomposition of gel precursor was studied using EGA (FTIR)-TGA method. Chemical composition of the obtained material was confirmed using X-ray diffraction and energy-dispersive X-ray spectroscopy. The morphology of β- Li 2 CoSiO 4 was studied using transmission electron microscopy. High temperature electrical conductivity of Li 2 CoSiO 4 was measured for the first time. Activation energies of the electrical conductivity of two Li 2 CoSiO 4 polymorphs (β and γ) were determined. The room temperature electrical conductivity of those materials was estimated as well.

Co-Precipitation Synthesis of BiFeO3 Powders

2010 ◽  
Vol 105-106 ◽  
pp. 286-288 ◽  
Author(s):  
Hai Yang Bo ◽  
Guo Qiang Tan ◽  
Hong Yan Miao ◽  
Ao Xia
Keyword(s):  
Calcination Temperature ◽  
Bismuth Ferrite ◽  
Precipitation Method ◽  
Molar Ratio ◽  
Diffraction Field ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Infrared Spectrophotometer ◽  
Lower Temperature ◽  
Co Precipitation

Bismuth ferrite powders were synthesized by a simple citric acid complexing co-precipitation method at much lower temperature of 600°C. The work studies the calcination temperature and molar ratio of Fe and Bi on the structure and morphology. The as-prepared BiFeO3 powder was characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscope and Fourier transform infrared spectrophotometer. The result shows that the phase pure BiFeO3 powders with cubic morphology were prepared as the calcination temperature was 600°C and molar ratio of Fe and Bi was 1:1. The nanoparticles was uniform with the size of about 200nm.

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