scholarly journals Effect of chemical composition on the electrical conductivity of gneiss at high temperatures and pressures

Solid Earth ◽  
2018 ◽  
Vol 9 (2) ◽  
pp. 233-245 ◽  
Author(s):  
Lidong Dai ◽  
Wenqing Sun ◽  
Heping Li ◽  
Haiying Hu ◽  
Lei Wu ◽  
...  
Keyword(s):  
Electrical Conductivity ◽  
Temperature Region ◽  
Ionic Conduction ◽  
Complex Impedance ◽  
Weight Percent ◽  
Spectroscopic Technique ◽  
Ultrahigh Pressure ◽  
Chemical Compositions ◽  
Metamorphic Belt ◽  
Lower Temperature

Abstract. The electrical conductivity of gneiss samples with different chemical compositions (WA = Na2O + K2O + CaO  =  7.12, 7.27 and 7.64 % weight percent) was measured using a complex impedance spectroscopic technique at 623–1073 K and 1.5 GPa and a frequency range of 10−1 to 106 Hz. Simultaneously, a pressure effect on the electrical conductivity was also determined for the WA = 7.12 % gneiss. The results indicated that the gneiss conductivities markedly increase with total alkali and calcium ion content. The sample conductivity and temperature conform to an Arrhenius relationship within a certain temperature range. The influence of pressure on gneiss conductivity is weaker than temperature, although conductivity still increases with pressure. According to various ranges of activation enthalpy (0.35–0.52 and 0.76–0.87 eV) at 1.5 GPa, two main conduction mechanisms are suggested that dominate the electrical conductivity of gneiss: impurity conduction in the lower-temperature region and ionic conduction (charge carriers are K+, Na+ and Ca2+) in the higher-temperature region. The electrical conductivity of gneiss with various chemical compositions cannot be used to interpret the high conductivity anomalies in the Dabie–Sulu ultrahigh-pressure metamorphic belt. However, the conductivity–depth profiles for gneiss may provide an important constraint on the interpretation of field magnetotelluric conductivity results in the regional metamorphic belt.

scholarly journals Effect of chemical composition on the electrical conductivity of gneiss at high temperatures and pressures

2017 ◽  
Author(s):  
Lidong Dai ◽  
Wenqing Sun ◽  
Heping Li ◽  
Haiying Hu ◽  
Lei Wu ◽  
...  
Keyword(s):  
Temperature Region ◽  
Ionic Conduction ◽  
Complex Impedance ◽  
Total Content ◽  
Weight Percent ◽  
Spectroscopic Technique ◽  
Ultrahigh Pressure ◽  
Chemical Compositions ◽  
Metamorphic Belt ◽  
Lower Temperature

Abstract. Electrical conductivities of the gneiss samples with different chemical compositions [WA=Na2O+K2O+CaO=7.12 %, 7.27 % and 7.64 % in weight percent] were measured using a complex impedance spectroscopic technique at 623–1073 K and 1.5 GPa in the frequency range of 10−1 to 106 Hz. In addition, conductivities of gneiss with WA = 7.12 % were measured at 623‒1073 K and 0.5‒2.0 GPa. The results indicated that the conductivities of gneiss markedly increase with the increase of the total content of alkali and calcium ions. The conductivity of gneiss and temperature conform to an Arrhenius relation at a certain temperature range. The influence of pressure on conductivity of gneiss is weaker than that of temperature, and the conductivity increases with the increasing pressure. According to the various ranges of activation enthalpy (0.35‒0.52 eV and 0.76‒0.87 eV) corresponding to higher and lower temperature regions at 1.5 GPa, two main conduction mechanisms were suggested to dominate the conductivity of gneiss: impurity conduction in the lower temperature region and ionic conduction (charge carriers are K+, Na+ and Ca2+) in the higher temperature region. Finally, it was confirmed that gneisses with various chemical compositions can’t cause the high conductivity layers (HCLs) in Dabie-Sulu ultrahigh-pressure metamorphic belt.

Electrical Conductivity and Structural Studies on the Binary System BiI3-Ag2SO4

2012 ◽  
Vol 584 ◽  
pp. 521-525
Author(s):  
S. Austin Suthanthiraraj ◽  
Ayesha Saleem
Keyword(s):  
Electrical Conductivity ◽  
Binary System ◽  
Ionic Conduction ◽  
Structural Characteristics ◽  
Complex Impedance ◽  
Present System ◽  
Rapid Melt Quenching ◽  
Ionic Nature ◽  
Electrochemical Devices ◽  
Silver Sulphate

A new solid-state pseudo binary system BiI3_-Ag2SO4 involving bismuth triiodide (BiI3) and a silver oxysalt namely silver sulphate (Ag2SO4) has been prepared using rapid melt-quenching technique. AC conductivity studies have been carried out on the nine different samples of the (BiI3)x –- (Ag2SO4)(1-x) system with compositions corresponding to x=0.1,0.2,0.3,0.4,0.5,0.6,0.7,0.8 and 0.9 mole fraction at temperatures ranging from room temperature (298 K) to 433K. The bulk resistance values estimated using complex impedance plots indicated that electrical conductivity of the synthesized solid specimens would vary from 2.9 x10-2 to 3.4 x10-6Scm-1 thus suggesting the present system to be ionic in nature. The extent of ionic conduction due to Ag + cation has also been analyzed using Wagner’s dc polarization technique whereas detailed structural characteristics of the various compositions derived from Fourier transform infrared (FTIR) spectroscopy and features of surface morphology of these samples obtained using scanning electron microscopy (SEM) have further supported the ionic nature of the chosen system and suggested possible application as a solid electrolyte in electrochemical devices.

scholarly journals Fast Diffusion of Iron in Single Crystal Rutile and Iron Doped Rutile

1983 ◽  
Vol 24 ◽  
Author(s):  
J. Sasaki ◽  
N. L. Peterson ◽  
L. C. De Jonghe
Keyword(s):  
Electrical Conductivity ◽  
Ionic Conductivity ◽  
Pressure Dependence ◽  
Ionic Conduction ◽  
Complex Impedance ◽  
Fast Diffusion ◽  
Iron Ions ◽  
Impedance Measurements ◽  
Fe Content ◽  
Shear Structure

ABSTRACTTracer diffusion coefficients of Fe, DFe* in single crystals of rutile and of 0 –2.0% Fe doped rutile were measured. The oxygen pressure dependence of DFe* in pure rutile showed complicated behavior. The values of DFe* may consist of contributions from Fe2+ ions diffusing by an interstitial mechanism and from Fe3+ ions diffusing by an interstitialcy mechanism in cooperation with tetravalent titanium interstitial ions, Tii. The value of DFe* in Fe doped rutile attains a saturation value when the Fe content reaches about 0.1%, D*Fe decreases drastically when the Fe content exceeds about 0.35%. Complex impedance measurements of electrical conductivity indicate the existence of ionic conduction for Fe doped rutile containing less than 0.35% of Fe. The small ionic conductivity relative to the values of D*Fe suggests that only a small fraction of the iron ions are highly mobile. Above 0.35% Fe, the observed drastic decrease in D*Fe may result from the formation of a shear structure In highly doped rutile.

Effects of Microstructure on the Electrical Conductivity of SrCo0.8Fe0. 2O3_δ

1999 ◽  
Vol 575 ◽  
Author(s):  
K. Zhang ◽  
M. Miranova ◽  
Y. L. Yang ◽  
A. J. Jacobson ◽  
K. Salama
Keyword(s):  
Activation Energy ◽  
Electrical Conductivity ◽  
Grain Size ◽  
Size Effect ◽  
Temperature Region ◽  
Grain Size Effect ◽  
Average Grain Size ◽  
Lower Temperature ◽  
Lower Temperature Region ◽  
Test Temperature Range

ABSTRACTThe effect of microstructure on the electrical conductivity of SrCO0.8Fe0.2O3_δ (SCFO) was investigated in air using a four-point dc method. In the test temperature range of 200 to 900 °C, the electrical conductivity of this material was observed to increase with the increase of the average grain size in the lower temperature region where the conductivity increases with the increase of the temperature. The activation energy is decreased with the increase of the grain size in this region, 0.04 ± 0.004 ev for 4.1μm sample and 0.01 ± 0.001 ev for 14.8 μm sample. When temperature is further increased, the conductivity of this material decreases with the increase of the temperature, and the grain size effect becomes less noticeable.

Steady State Conduction Behaviour of Liquid Crystalline Polyurethane

2013 ◽  
Vol 856 ◽  
pp. 210-214
Author(s):  
Jitender Kumar Quamara ◽  
Satish Kumar Mahna ◽  
Sohan Lal ◽  
Pushkar Raj
Keyword(s):  
Activation Energy ◽  
Steady State ◽  
Temperature Region ◽  
Liquid Crystalline ◽  
Ionic Conduction ◽  
Schottky Type ◽  
Order Of Magnitude ◽  
Higher Temperature ◽  
Lower Temperature ◽  
Type Conduction

The steady state measurements in Liquid crystalline polyurethane (LCPU) have been investigated for different fields (4 - 45 kV/cm) and temperatures (50°-220°C). The nature of conduction processes has been determined by estimating ion jump distances (a) and Schottky coefficients. The order of magnitude of a in the temperature region 150°C and below does not seem to support an ionic conduction. However the magnitude of a at higher temperatures (180°C and above) indicates the possibility of ionic conduction. There is a definite possibility of a Schottky type conduction at lower temperature and a Poole Frankel type conduction at higher temperature (100°C). The activation energy associated with the high temperature region lies between 0.26 eV and 0.65 eV depending on the field whereas in the low temperature region the activation energy lies between 0.82 eV and 0.95 eV depending on the applied electric field. The dual slopes in the log I versus 1/T curves indicate the presence of more than one type of trapping levels.

Effect of MCl (M = Na, K) addition on microstructure and electrical conductivity of forsterite

2020 ◽  
Vol 92 (1) ◽  
pp. 10901
Author(s):  
Saloua El Asri ◽  
Hamid Ahamdane ◽  
Lahoucine Hajji ◽  
Mohamed El Hadri ◽  
Moulay Ahmed El Idrissi Raghni ◽  
...  
Keyword(s):  
Heat Treatment ◽  
Electrical Conductivity ◽  
Single Phase ◽  
Sol Gel ◽  
Complex Impedance ◽  
Transmission Spectra ◽  
Electrical Measurements ◽  
Cation Type ◽  
Edx Analyses ◽  
The Fourier Transform

Forsterite single phase powder Mg2SiO4 was synthesized by sol–gel method alongside with heat treatment, using two different cation alkaline salts MCl as mineralizers (M = Na, K) with various mass percentages (2.5, 5, 7.5, and 10 wt.%). In this work, we report on the effect of the cation type and the added amount of used mineralizer on microstructure and electrical conductivity of Mg2SiO4. The formation of forsterite started at 680–740  °C and at 630–700  °C with KCl and NaCl respectively, as shown by TG-DTA and confirmed by XRD. Furthermore, the Fourier transform infrared (FTIR) transmission spectra indicated bands corresponding to vibrations of forsterite structure. The morphology and elemental composition of sintered ceramics were examined by SEM-EDX analyses, while their densities, which were measured by Archimedes method, increased with addition of both alkaline salts. The electrical measurements were performed by Complex Impedance Spectroscopy. The results showed that electrical conductivity increased with the addition of both mineralizers, which was higher for samples prepared with NaCl than those prepared with KCl.

Boron cycling by subducted lithosphere; insights from diamondiferous tourmaline from the Kokchetav ultrahigh-pressure metamorphic belt

2008 ◽  
Vol 72 (14) ◽  
pp. 3531-3541 ◽  
Author(s):  
Tsutomu Ota ◽  
Katsura Kobayashi ◽  
Takuya Kunihiro ◽  
Eizo Nakamura
Keyword(s):  
Ultrahigh Pressure ◽  
Metamorphic Belt

Complex impedance and ionic conduction of single-crystalline BaTiO3

2016 ◽  
Vol 504 (1) ◽  
pp. 64-71 ◽  
Author(s):  
Keiji Shiga ◽  
Hirokazu Katsui ◽  
Takashi Goto
Keyword(s):  
Ionic Conduction ◽  
Complex Impedance ◽  
Single Crystalline

Thermoelectric Properties of n-type (Bi2Se3)x(Bi2Te3)1-x Crystals Prepared by Zone Melting

2008 ◽  
Vol 368-372 ◽  
pp. 547-549
Author(s):  
Jun Jiang ◽  
Ya Li Li ◽  
Gao Jie Xu ◽  
Ping Cui ◽  
Li Dong Chen
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Carrier Concentration ◽  
Thermoelectric Properties ◽  
Figure Of Merit ◽  
Zone Melting ◽  
Chemical Compositions ◽  
Melting Method ◽  
Temperature Range

In the present study, n-type (Bi2Se3)x(Bi2Te3)1-x crystals with various chemical compositions were fabricated by the zone melting method. Thermoelectric properties, including Seebeck coefficient (α), electrical conductivity (σ) and thermal conductivity (κ), were measured in the temperature range of 300-500 K. The influence of the variations of Bi2Te3 and Bi2Se3 content on thermoelectric properties was studied. The increase of Bi2Se3 content (x) caused an increase in carrier concentration and thus an increase of σ and a decrease of α. The maximum figure of merit (ZT = α2σT/κ) of 0.87 was obtained at about 325 K for the composition of 93%Bi2Te3-7%Bi2Se3 with doping TeI4.

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