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.

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.

scholarly journals Electrical Conduction in Some Nickelates

2011 ◽  
Vol 8 (1) ◽  
pp. 83-90
Author(s):  
Kanchan Gaur ◽  
Shalini Shalini ◽  
Satyendra Singh
Keyword(s):  
Temperature Region ◽  
Conduction Mechanism ◽  
Charge Carriers ◽  
Band Model ◽  
Orthorhombic Unit Cell ◽  
Dominant Conduction Mechanism ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Lower Temperature Region ◽  
Band Type

This paper reports electrical conductivity (s) and Seebeck coefficient (s) study on rare-earth nickelates RNiO3 where R = Nd, Sm and Eu in the temperature range 400-1200 K. They have orthorhombic unit cell. The majority charge carriers are holes throughout the measurement. Both s and S variations show three regions. In higher temperature region (Above 1000K) dominant conduction mechanism is intrisic band type whereas below this temperature, hopping of holes from Ni3+ to Ni2+ centres takes place. In lower temperature region, the electrical conductions is taken over by acceptor type impurities. The conduction mechanism is explained on the basis of every band model. Break temperatures as well as mobility have also been evaluated.

scholarly journals Femtosecond tunneling of polarons in Pb5Cr3F19

2014 ◽  
Vol 04 (03) ◽  
pp. 1450020
Author(s):  
A. Levstik ◽  
C. Filipič ◽  
G. Tavčar ◽  
B. Žemva
Keyword(s):  
Phase Transition ◽  
Electrical Conductivity ◽  
Low Temperatures ◽  
Dielectric Response ◽  
Ferroelectric Phase Transition ◽  
Ferroelectric Phase ◽  
Charge Carriers ◽  
Complex Dielectric Constant ◽  
Ac Electrical Conductivity ◽  
Small Polarons

The complex dielectric constant/ac electrical conductivity was investigated as a function of frequency and temperature in Pb 5 Cr 3 F 19. The system undergoes a ferroelectric phase transition at higher temperatures. At lower temperatures the real part of the complex ac electric conductivity was found to follow the universal dielectric response (UDR) σ′ ∝ νs, typical for hopping or tunneling of localized charge carriers. A detailed analysis of the temperature dependence of the UDR parameter s in terms of the theoretical model for tunneling of small polarons revealed that, at low temperatures, this mechanism governs the charge transport in Pb 5 Cr 3 F 19. The value of the inverse attempt frequency τ0 indicates the femtosecond tunneling of polarons in the system similar to the Büttiker–Landauer transversal time.

scholarly journals Pressure-Induced Structural Phase Transition and Metallization in Ga2Se3 up to 40.2 GPa under Non-Hydrostatic and Hydrostatic Environments

Crystals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 746
Author(s):  
Meiling Hong ◽  
Lidong Dai ◽  
Haiying Hu ◽  
Xinyu Zhang
Keyword(s):  
Phase Transition ◽  
Electrical Conductivity ◽  
High Pressure ◽  
Phase Transformation ◽  
Transport Properties ◽  
Electrical Transport ◽  
Structural Phase ◽  
Structure Evolution ◽  
Systematic Research ◽  
Electrical Transport Properties

A series of investigations on the structural, vibrational, and electrical transport characterizations for Ga2Se3 were conducted up to 40.2 GPa under different hydrostatic environments by virtue of Raman scattering, electrical conductivity, high-resolution transmission electron microscopy, and atomic force microscopy. Upon compression, Ga2Se3 underwent a phase transformation from the zinc-blende to NaCl-type structure at 10.6 GPa under non-hydrostatic conditions, which was manifested by the disappearance of an A mode and the noticeable discontinuities in the pressure-dependent Raman full width at half maximum (FWHMs) and electrical conductivity. Further increasing the pressure to 18.8 GPa, the semiconductor-to-metal phase transition occurred in Ga2Se3, which was evidenced by the high-pressure variable-temperature electrical conductivity measurements. However, the higher structural transition pressure point of 13.2 GPa was detected for Ga2Se3 under hydrostatic conditions, which was possibly related to the protective influence of the pressure medium. Upon decompression, the phase transformation and metallization were found to be reversible but existed in the large pressure hysteresis effect under different hydrostatic environments. Systematic research on the high-pressure structural and electrical transport properties for Ga2Se3 would be helpful to further explore the crystal structure evolution and electrical transport properties for other A2B3-type compounds.

Electrical conductivity and the nature of charge carriers in glasses of the Tl2O-B2O3 system

2008 ◽  
Vol 34 (3) ◽  
pp. 227-239 ◽  
Author(s):  
I. A. Sokolov ◽  
I. V. Murin ◽  
V. D. Khripun ◽  
N. A. Valova ◽  
Yu. K. Startsev ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Charge Carriers

ELECTRONIC STATE CALCULATION OF MANGANESE DIOXIDE ELECTRODE WITH ADDITIVE TRANSITION METALS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4255-4260 ◽  
Author(s):  
BONG-SEO KIM ◽  
SU-DONG PARK ◽  
HEE-WOONG LEE ◽  
DONG-YOON LEE ◽  
WON-SUB CHUNG
Keyword(s):  
Electrical Conductivity ◽  
Transition Metals ◽  
Theoretical Calculation ◽  
Manganese Dioxide ◽  
Cluster Model ◽  
Electronic States ◽  
Deposition Method ◽  
Energy Band Gap ◽  
Anodic Deposition ◽  
Better Than

The electronic states of manganese dioxide substituted with transition metals were theoretically calculated by DV-Xα method, cluster model was Mn 15 O 56 and Mn 14 XO 56 (X = transition metal). The energy band gap of manganese-X oxides is lower than that of manganese dioxide from theoretical calculation. Also it is identified that the electrical conductivity of manganese-tungsten oxide is better than that of manganese dioxide from experiment of anodic deposition method. It is confirmed that the theoretical calculation coincides with experimental results.

Copolymer-Nanoparticles Mixture in a Cylindrical Pore

NANO ◽  
2017 ◽  
Vol 12 (04) ◽  
pp. 1750045
Author(s):  
Jun-Xing Pan ◽  
Yu-Qi Guo ◽  
Yu-Fang Han ◽  
Min-Na Sun ◽  
Jin-Jun Zhang
Keyword(s):  
Phase Transition ◽  
Electrical Conductivity ◽  
Polymer Nanocomposites ◽  
Diblock Copolymer ◽  
Large Diameter ◽  
Small Diameter ◽  
Confinement Effect ◽  
Cylindrical Pore ◽  
Disorder Phase Transition ◽  
Novel Structures

Computer simulation is carried out for investigating the effect of nanoparticles on diblock copolymer morphology under cylindrical confinement. The phase diagrams of polymer nanocomposites with nanoparticle-block wetting strength and concentration of nanoparticles are obtained in different nanopores. In small diameter nanopore, there is almost no influence of nanoparticles on the diblock copolymer morphology because of the stronger confinement effect; in middle diameter nanopore, the system can self-assemble into various novel structures due to the interaction between confinement effect and nanoparticles effect; in large diameter nanopore, due to the stronger effect of nanoparticles, a disorder-order-disorder phase transition occurs with the wetting strength and concentration of nanoparticles increasing. This result can be useful in designing new nanocomposites with advanced electrical conductivity and/or mechanical strength.

Effects of Glycerol on the Thermal Properties of Phosphate Buffered Saline and Porcine Liver at Subzero Temperatures

2007 ◽  
Author(s):  
Jeung H. Choi ◽  
John C. Bischof
Keyword(s):  
Phase Transition ◽  
Thermal Properties ◽  
Property Values ◽  
Insufficient Data ◽  
Porcine Liver ◽  
Water Ice ◽  
Subzero Temperatures ◽  
Temperature Ranges ◽  
Phase Change Phenomena ◽  
Phosphate Buffered Saline

Improvements in the prediction of thermal behavior during cryosurgery and cryopreservation can help improve the outcome of these cryobiological applications. The accuracy of the models depends on numerous factors including the kinetics and energy release during phase change phenomena and knowledge of thermal properties. Furthermore, connecting the thermal properties to crystalline, amorphous, and other phases adds an important mechanistic dimension that can also improve and direct an outcome. However, insufficient data for thermal properties in the subzero domain result in reliance on property estimations based usually upon tabulated water-ice data or weight averaged values from known materials primarily in temperature ranges above −40 °C [1]. This study focused on expanding the thermal properties database for both solutions and tissues. Results for Phosphate Buffered Saline (PBS) and porcine liver with glycerol at subzero temperatures (−150 ∼ 0 °C) are reported. The shifting of thermal property values due to sample crystallization, amorphous phase transition, and melting is discussed.

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