Solid to superionic transition in iron oxide-hydroxide

2021 ◽  
Author(s):  
Qingyang Hu ◽  
Mingqiang Hou ◽  
Yu He
Keyword(s):  
Electrical Conductivity ◽  
Extreme Pressure ◽  
Hydrous Minerals ◽  
Water Ice ◽  
Individual Unit ◽  
Freely Moving ◽  
Superionic Transition ◽  
Increasing Temperature ◽  
Isotopic Mixing ◽  
Redox Equilibria

<p>At planetary interior conditions, water ice has been proved to enter a superionic phase recently since it was predicted about 30-year ago. Hydrogen in superionic water become liquid-like, and move freely within solid oxygen lattice. Under extreme pressure and temperature conditions of Earth’s deep mantle, the solid-superionic transition can also occur readily in the pyrite-type FeO<sub>2</sub>Hx, a candidate mineral in the lower mantle and probably also in other hydrous minerals. We find that when the pressure increases beyond 73 GPa at room temperature, symmetric hydroxyl bonds are softened and the H<sup>+</sup> (or proton) become diffusive within the vicinity of its crystallographic site. Increasing temperature under pressure, the diffusivity of hydrogen is extended beyond individual unit cell to cover the entire solid, and the electrical conductivity soars, indicating a transition to the superionic state which is characterized by freely-moving proton and solid FeO<sub>2</sub> lattice. The superionic hydrogen will dramatically change the geophysical picture of electrical conductivity and magnetism, as well as geochemical processes of hydrogen isotopic mixing and redox equilibria at local regions of Earth’s deep interiors.</p>

Electronic Transport Properties of Hot-Pressed B6Si

1987 ◽  
Vol 97 ◽  
Author(s):  
C. Wood ◽  
D. Emin ◽  
R. S. Feigelson ◽  
I. D. R. Mackinnon
Keyword(s):  
Electrical Conductivity ◽  
Seebeck Coefficient ◽  
Transport Properties ◽  
Electronic Transport ◽  
Hall Mobility ◽  
Anomalous Behavior ◽  
Nominal Composition ◽  
Electronic Transport Properties ◽  
Increasing Temperature ◽  
P Type

ABSTRACTMeasurements of the electrical conductivity, Seebeck coefficient and Hall mobility from -300 K to -1300 K have been carried out on multiphase hotpressed samples of the nominal composition B6Si. In all samples the conductivity and the p-type Seebeck coefficient both increase smoothly with increasing temperature. By themselves, these facts suggest small-polaronic hopping between inequivalent sites. The measured Hall mobilities are always low, but vary in sign. A possible explanation is offered for this anomalous behavior.

scholarly journals The Electrical Conductivity of Some Hydrous and Anhydrous Molten Silicates as a Function of Temperature and Pressure

2021 ◽  
Author(s):  
◽  
John Satherley
Keyword(s):  
Electrical Conductivity ◽  
Quartz Crystal ◽  
Pressure Coefficient ◽  
General Picture ◽  
Water Composition ◽  
Mixed Alkali ◽  
Mixed Alkali Effect ◽  
Temperature And Pressure ◽  
Increasing Temperature ◽  
Arrhenius Temperature

<p>This thesis is concerned with the measurement and interpretation of electrical conductivity in molten silicates. Physicochemical properties and structural models of silica and silicates are reviewed first, to give a general picture of their behaviour. Electrical conductivity was measured as a function of temperature, pressure and water composition. To make these measurements an internally heated pressure vessel, designed to operate at temperatures up to 1200 degrees C and pressures up to 5 kbars was constructed. Conductivity measurements were made on the following anhydrous and hydrous silicate melts: SiO2/Na2O 60/40, 65/35, 75/25, 78/22 mol%; SiO2/Na2O/CaO 72/24/4 mol%; Mt. Erebus lava; SiO2/Na2O 78/22 mol% + ~5 wt% H2O and Mt. Erebus lava + ~4 wt% H2O in the temperature range 850-1000 degrees C and the pressure range 0-1.3 kbar. Arrhenius temperature and pressure dependencies on conductivity were observed. The pressure coefficient of conductivity was zero for the anhydrous melts well above Tg but small and positive for the hydrous silicates. Water caused ~40% reduction in conductivity when added to a melt which was accounted for in terms of the mixed alkali effect. Conductivity isobars for the hydrous silicates passed through a maximum as a function of increasing temperature. The conductivity behaviour as a function of temperature and pressure is analogous to that observed in partially ionised liquids and is intrepretated in an identical way. The range of operation of a piezoelectric alpha-quartz crystal viscometer was extended to allow measurement of viscosity as a function of temperature.</p>

scholarly journals Structural and Electrical Properties of ZnO Varistor with Different Particle Size for Initial Oxides Materials

2019 ◽  
Vol 2 (2) ◽  
pp. 20-31 ◽  
Author(s):  
Susan A Amin
Keyword(s):  
Electrical Conductivity ◽  
Particle Size ◽  
Nonlinear Coefficient ◽  
Hexagonal Wurtzite Structure ◽  
The Other ◽  
Breakdown Field ◽  
Residual Voltage ◽  
Structural And Electrical Properties ◽  
Increasing Temperature ◽  
Initial Starting

We report here structural, electrical and dielectric properties of ZnO varistors prepared with two different particle sizes for initial starting oxides materials (5 µm and 200 nm). It is found that the particle size of ZnO does not influence the hexagonal wurtzite structure of ZnO, while the lattice parameters, crystalline diameter, grain size and Zn-O bond length are affected. The nonlinear coefficient, breakdown field and barrier height are decreased from 18.6, 1580 V/cm and 1.153 eV for ZnO micro to 410 V/cm, 7.26 and 0.692 eV for ZnO nano.  While, residual voltage and electrical conductivity of upturn region are increased from 2.08 and 2.38x10-5 (Ω.cm)-1 to 4.55 and 3.03x10-5 (Ω.cm)-1. The electrical conductivity increases by increasing temperature for both varistors, and it is higher for ZnO nano than that of ZnO micro.  The character of electrical conductivity against temperature is divided into three different regions over the temperature intervals as follows; (300 K ≤ T ≤ 420 K), (420 K ≤ T ≤ 580 K) and (580 K ≤ T ≤ 620 K), respectively. The activation energy is increased in the first region from 0.141 eV for ZnO micro to 0.183 eV for ZnO nano and it is kept nearly constant in the other two regions. On the other hand, the average conductivity deduced through dielectric measurements is increased from 2.54x10-7 (Ω.cm)-1 for ZnO micro to 49x10-7 (Ω.cm)-1. Similar behavior is obtained for the conductivities of grains and grain boundaries. The dielectric constant decreases as the frequency increases for both varistors, and it is higher for ZnO nano than that of ZnO micro. These results are discussed in terms of free excited energy and strength of link between grains of these varistors.

High-temperature thermoelectric properties of n-type BayNixCo4−xSb12

2001 ◽  
Vol 16 (12) ◽  
pp. 3343-3346 ◽  
Author(s):  
X. F. Tang ◽  
L. M. Zhang ◽  
R. Z. Yuan ◽  
L. D. Chen ◽  
T. Goto ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
High Temperature ◽  
Seebeck Coefficient ◽  
Thermoelectric Properties ◽  
Electron Concentration ◽  
Lattice Thermal Conductivity ◽  
Filling Fraction ◽  
Ni Content ◽  
Increasing Temperature

Effects of Ba filling fraction and Ni content on the thermoelectric properties of n-type BayNixCo4−xSb12 (x = 0−0.1, y = 0−0.4) were investigated at temperature range of 300 to 900 K. Thermal conductivity decreased with increasing Ba filling fraction and temperature. When y was fixed at 0.3, thermal conductivity decreased with increasing Ni content and reached a minimum value at about x = 0.05. Lattice thermal conductivity decreased with increasing Ni content, monotonously (y ≤ 0.1). Electron concentration and electrical conductivity increased with increasing Ba filling fraction and Ni content. Seebeck coefficient increased with increasing temperature and decreased with increasing Ba filling fraction and Ni content. The maximum ZT value of 1.25 was obtained at about 900 K for n-type Ba0.3Ni0.05Co3.95Sb12.

Wärmeleitfähigkeit, elektrische Leitfähigkeit, Hall-Effekt, Thermospannung und spezifische Wärme von Ag2Se

1962 ◽  
Vol 17 (10) ◽  
pp. 886-889 ◽  
Author(s):  
Y. Baer ◽  
G. Busch ◽  
C. Fröhlich ◽  
E. Steigmeier
Keyword(s):  
Thermal Conductivity ◽  
Electrical Conductivity ◽  
Low Temperature ◽  
Specific Heat ◽  
Thermoelectric Power ◽  
Hall Coefficient ◽  
A Value ◽  
Price Formula ◽  
Elektrische Leitfähigkeit ◽  
Increasing Temperature

The thermal conductivity, electrical conductivity. Hall coefficient und thermoelectric power of Ag2Se have been measured between 80 and 600°K. In the low temperature semiconductor phase the thermal conductivity increases with increasing temperature due to the high amount of carrier contribution. The latter has been calculated using the Price formula. Agreement with experiment is satisfactory. The specific heat has been measured between 30 and 200°C. For the latent heat a value of (5.7 ± 0.5) cal/gr was determined in agreement with measurements of Bellati and Lussana 4. In addition to the transition at 133 °C an unknown new transition has been found at about 90 °C.

scholarly journals Температурная зависимость проводимости нитевидных кристаллов теллура

2021 ◽  
Vol 55 (6) ◽  
pp. 493
Author(s):  
М.Р. Рабаданов ◽  
А.А. Степуренко ◽  
А.Э. Гумметов ◽  
А.М. Исмаилов
Keyword(s):  
Electrical Conductivity ◽  
Electron Microscope ◽  
Comparative Analysis ◽  
Single Crystal ◽  
Diffuse Scattering ◽  
Epitaxial Film ◽  
Thermal Excitation ◽  
Increasing Temperature ◽  
Classical Size ◽  
Scanning Electron

In the temperature range 77−273K, a comparative analysis of the electrical conductivity of a whisker, an epitaxial film, and a single crystal of tellurium was undertaken. The electrical conductivity of the film and the single crystal increased monotonically up to 200K, then began to rise steeply, corresponding to thermal excitation of intrinsic carriers. The electrical conductivity of whiskers decreased with increasing temperature to 230K, after which it began to increase more gradually. It is assumed that in the case of tellurium whiskers, the classical size effect took place: the decrease in electrical conductivity was due to diffuse scattering of carriers by the lateral surface of the tellurium crystal and was intensified with increasing temperature. The uneven, tightly-convoluted surface of the samples was shown in images produced in a scanning electron microscope in the nanometer range.

scholarly journals The Electrical Conductivity of Some Hydrous and Anhydrous Molten Silicates as a Function of Temperature and Pressure

2021 ◽  
Author(s):  
◽  
John Satherley
Keyword(s):  
Electrical Conductivity ◽  
Quartz Crystal ◽  
Pressure Coefficient ◽  
General Picture ◽  
Water Composition ◽  
Mixed Alkali ◽  
Mixed Alkali Effect ◽  
Temperature And Pressure ◽  
Increasing Temperature ◽  
Arrhenius Temperature

<p>This thesis is concerned with the measurement and interpretation of electrical conductivity in molten silicates. Physicochemical properties and structural models of silica and silicates are reviewed first, to give a general picture of their behaviour. Electrical conductivity was measured as a function of temperature, pressure and water composition. To make these measurements an internally heated pressure vessel, designed to operate at temperatures up to 1200 degrees C and pressures up to 5 kbars was constructed. Conductivity measurements were made on the following anhydrous and hydrous silicate melts: SiO2/Na2O 60/40, 65/35, 75/25, 78/22 mol%; SiO2/Na2O/CaO 72/24/4 mol%; Mt. Erebus lava; SiO2/Na2O 78/22 mol% + ~5 wt% H2O and Mt. Erebus lava + ~4 wt% H2O in the temperature range 850-1000 degrees C and the pressure range 0-1.3 kbar. Arrhenius temperature and pressure dependencies on conductivity were observed. The pressure coefficient of conductivity was zero for the anhydrous melts well above Tg but small and positive for the hydrous silicates. Water caused ~40% reduction in conductivity when added to a melt which was accounted for in terms of the mixed alkali effect. Conductivity isobars for the hydrous silicates passed through a maximum as a function of increasing temperature. The conductivity behaviour as a function of temperature and pressure is analogous to that observed in partially ionised liquids and is intrepretated in an identical way. The range of operation of a piezoelectric alpha-quartz crystal viscometer was extended to allow measurement of viscosity as a function of temperature.</p>

scholarly journals Electrical Conductivity of Fluorite and Fluorine Conduction

Minerals ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 72 ◽  
Author(s):  
Hanyong Liu ◽  
Qiao Zhu ◽  
Xiaozhi Yang
Keyword(s):  
Electrical Conductivity ◽  
Charge Carrier ◽  
Electrical Conduction ◽  
Experimental Studies ◽  
Conductivity Data ◽  
Arrhenius Law ◽  
Piston Cylinder ◽  
Sample Composition ◽  
Increasing Temperature ◽  
Loaded Piston

Fluorine is a species commonly present in many minerals in the Earth’s interior, with a concentration ranging from a few ppm to more than 10 wt. %. Recent experimental studies on fluorine-bearing silicate minerals have proposed that fluorine might be an important charge carrier for electrical conduction of Earth materials at elevated conditions, but the results are somewhat ambiguous. In this investigation, the electrical conductivity of gem-quality natural single crystal fluorite, a simple bi-elemental (Ca and F) mineral, has been determined at 1 GPa and 200–650 °C in two replication runs, by a Solartron-1260 Impedance/Gain Phase analyzer in an end-loaded piston-cylinder apparatus. The sample composition remained unchanged after the runs. The conductivity data are reproducible between different runs and between heating-cooling cycles of each run. The conductivity (σ) increases with increasing temperature, and can be described by the Arrhenius law, σ = 10^(5.34 ± 0.07)·exp[−(130 ± 1, kJ/mol)/(RT)], where R is the gas constant and T is the temperature. According to the equation, the conductivity reaches ~0.01 S/m at 650 °C. This elevated conductivity is strong evidence that fluorine is important in charge transport. The simple construction of this mineral indicates that the electrical conduction is dominated by fluoride (F−). Therefore, fluorine is potentially an important charge carrier in influencing the electrical property of Fluorine-bearing Earth materials.

Grain Size and Chemical Composition Effects on the Grain Boundary Resistance of Ceria

2002 ◽  
Vol 730 ◽  
Author(s):  
Xiao-Dong Zhou ◽  
Harlan U. Anderson ◽  
Wayne Huebner
Keyword(s):  
Electrical Conductivity ◽  
Grain Size ◽  
Grain Boundary ◽  
Boundary Resistance ◽  
Impedance Spectra ◽  
Total Resistance ◽  
Boundary Area ◽  
Oxygen Ions ◽  
Composition Effects ◽  
Increasing Temperature

AbstractStudies related to the effects of grain size (30nm – 5.0μm) on the electrical conductivity of undoped CeO2 and Ce0.90Gd0.10O1.95 were performed. A series of impedance spectra as a function of temperature and grain size were analyzed. It was found that the ratio of the grain boundary resistance to the total resistance became lower with decreasing grain size, increasing temperature or increasing Gd content. For the case of Gd doped CeO2, the source of the grain boundary resistance may be due to the trapping of oxygen ions in the grain boundary area.

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