Electrical Conduction Properties of Liquid Vanadates. II. The Sodium Vanadates

1972 ◽  
Vol 50 (17) ◽  
pp. 2871-2876 ◽  
Author(s):  
R. C. Kerby ◽  
J. R. Wilson
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Electrical Conduction ◽  
Ionic Conduction ◽  
Pressure Coefficient ◽  
Sodium Oxide ◽  
Liquid Sodium ◽  
Oxide Concentration ◽  
Increasing Temperature ◽  
Conduction Properties

The liquid sodium vanadates exhibited n-type semiconduction properties at sodium oxide concentrations less than 10 mol% and ionic conduction properties at concentrations greater than 25 mol%. The transition from semiconduction to ionic conduction occurred gradually as the sodium oxide concentration increased. The activation energy of conduction decreased with increasing sodium oxide concentration and increasing temperature. Negative oxygen partial pressure coefficients of conduction were found for sodium oxide concentrations less than 25 mol%. The oxygen partial pressure coefficient decreased with increasing temperature and sodium oxide concentration. The electrical conduction mechanism was considered to change from delocalized electron or polaron movement between V4+ and V5+ centers for the semiconducting liquid sodium vanadates to the probable movement of sodium and oxygen ions as the charge-carrying species forthe ionic liquid sodium vanadates.

Electrical Conduction Properties of Liquid Vanadates. I. Vanadium Pentoxide

1972 ◽  
Vol 50 (17) ◽  
pp. 2865-2870 ◽  
Author(s):  
R. C. Kerby ◽  
J. R. Wilson
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Temperature Coefficient ◽  
Vanadium Pentoxide ◽  
Electrical Conduction ◽  
Pressure Coefficient ◽  
Positive Temperature ◽  
Temperature Range ◽  
Partial Pressures ◽  
Conduction Properties

The electrical conductivity of liquid vanadium pentoxide was measured as a function of temperature and oxygen partial pressure. A positive temperature coefficient and a negative oxygen partial pressure coefficient of conduction were found for the temperature range 670 to 1000 °C and oxygen partial pressures from 0.1 to 1.0 atm. The activation energy of conduction was 0.77 eV and the oxygen partial pressure coefficient was −0.16. At oxygen partial pressures less than 0.1 atm, for the same temperature range, a negative temperature coefficient and a negative oxygen partial pressure coefficient of conduction were found.An n-type semiconduction model was used to explain the electrical conduction properties of liquid vanadium pentoxide at oxygen partial pressures greater than 0.1 atm. At lower oxygen partial pressures, electrical conduction was considered to occur by collective-electron conduction in partially filled 3d bands, due to an overlapping of the diffuse valence and conduction bands. The overlapping could result from a decrease in the cation separation distance in the melt due to the removal of oxygen ions from the melt.

Influences of oxygen impurity contained in nitrogen gas on the reactions of chromium with nitrogen

2005 ◽  
Vol 20 (10) ◽  
pp. 2745-2753 ◽  
Author(s):  
Yung-Shou Ho ◽  
Fong-Shung Huang ◽  
Fu-Hsing Lu
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Impurity ◽  
Nitrogen Gas ◽  
Available Nitrogen ◽  
Increasing Temperature ◽  
Pressure Changes ◽  
Annealing Experiments ◽  
Simultaneous Dissolution

In this research, the influences of the oxygen impurity contained in the commercially available nitrogen gas on the reactions of chromium pellets with nitrogen were investigated in the temperature range 600–1350 °C. A small amount of oxygen competed with the majority N2 to react with chromium in the annealing process. Analyzing the in situ oxygen partial pressure changes during annealing proved that the dissolution of oxygen in Cr and/or resultant CrxN (CrN or Cr2N) was exothermic and the solubility decreased with increasing temperature. It was found that the oxygen partial pressure decreased drastically to about 10−22 atm when specimens were annealed at 600 °C compared to a mere 10−5 atm for a blank test, while its value increased with temperature. The oxidation involved simultaneous dissolution of oxygen in specimens and formation of oxide scale. Moreover, comparing the aforementioned results with those obtained from additional annealing experiments preformed in argon gas showed that the formation of Cr2O3 might stem mainly from oxidation of the resultant nitrides instead of the metallic chromium.

scholarly journals The changes of Ba0.5Sr0.5Co0.8Fe0.2O3-δ perovskite oxide on heating in oxygen and carbon dioxide atmospheres

2014 ◽  
Vol 79 (9) ◽  
pp. 1141-1154 ◽  
Author(s):  
Sasa Zeljkovic ◽  
Toni Ivas ◽  
Sebastien Vaucher ◽  
Dijana Jelic ◽  
Ludwig Gauckler
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Elevated Temperatures ◽  
Oxygen Deficiency ◽  
Perovskite Oxide ◽  
X Ray ◽  
Equilibrium Reaction ◽  
Increasing Temperature

In the first part of this study, the oxygen deficiency, ?, in Ba0.5Sr0.5Co0.8Fe0.2O3 - ? (BSCF) was measured by means of thermogravimetry as a function of oxygen partial pressure, p(O2), in the range of 1.1?10?6 < p(O2)/% < 41.67 at elevated temperatures ranging 873 ? T/K ? 1073. It was shown that ? becomes more pronounced with increasing T and with decreasing p(O2). The isotherms ? vs. p(O2) were determined. The second part of this study relates to the reaction of CO2 with Ba0.5Sr0.5Co0.8Fe0.8O3-? perovskite oxide in the absence and presence of O2 at temperatures ranging from 673 to 973 K also by thermogravimetry. The reactivity of CO2 with BSCF increased with increasing temperature and increasing exposure to CO2. Reaction of CO2 with BSCF was described by a equilibrium reaction isotherms. The results of X-ray diffractometry evidenced that the exposure to CO2 leads to the formation of carbonates.

High temperature electrical conduction in nanoscale hafnia films under varying oxygen partial pressure

2010 ◽  
Vol 97 (8) ◽  
pp. 082102 ◽  
Author(s):  
Changhyun Ko ◽  
Michael Shandalov ◽  
Paul C. McIntyre ◽  
Shriram Ramanathan
Keyword(s):  
High Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Electrical Conduction

Erosion-Oxidation of Carbon Steel in the Convection Section of an Industrial Boiler Cofiring Coal–Water Fuel and Natural Gas

1997 ◽  
Vol 119 (3) ◽  
pp. 717-722 ◽  
Author(s):  
J. J. Xie ◽  
P. M. Walsh
Keyword(s):  
Carbon Steel ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Erosion Rate ◽  
Erosion Resistance ◽  
Metal Temperature ◽  
Gas Composition ◽  
Gas Velocity ◽  
Industrial Boiler ◽  
Increasing Temperature

Walsh et al. (1994) reported measurements of erosion of carbon steel by fly ash and unburned char particles in the convective heat transfer section of an industrial boiler cofiring coal–water fuel and natural gas. Erosion was enhanced by directing a small jet of nitrogen, air, or oxygen toward the surface of a test coupon mounted on an air-cooled tube. Ash and char particles that entered the jet from the surrounding flue gas were accelerated toward the surface of the specimen. Samples were exposed for 2 hours with metal temperature at 450, 550, and 650 K (350, 530, and 710°F). Changes in shape of the surface were measured using a surface profiler. Time-averaged maximum erosion rates were obtained from the differences between the original surface height and the lowest points in the profiles. Erosion was slowest at the lowest metal temperature, regardless of the jet gas composition. When the oxygen partial pressure at the sample surface was very small, under the nitrogen jet, erosion increased with increasing temperature over the range of temperatures investigated. At the intermediate oxygen level, in the air jet, erosion was most rapid at the intermediate temperature. In the presence of the pure oxygen jet erosion was slow at all three temperatures. A model was developed by Xie (1995) to describe wastage of tube material in the presence of the erosion by particle impacts and oxidation of the metal. The observed changes in erosion rate with temperature and oxygen concentration were consistent with a mechanism based upon the following assumptions: (1) Metal was eroded as a ductile material, at a rate that increased with increasing temperature. (2) Oxide was eroded as a brittle material, at a rate independent of temperature. (3) The oxide scale was strongly attached to the metal. (4) The erosion resistance of metal and scale was a linear combination of the resistances of the individual components. (5) Oxide formed according to the parabolic rate law, with a rate coefficient proportional to the square root of the oxygen partial pressure. (6) Erosion resistance from particles sticking to, or embedded in, the surface was negligible. Using the model and rate coefficients for metal and oxide erosion derived from the measurements, estimates were made of the erosion rate of a boiler tube as functions of impaction angle and gas velocity. Under the conditions of metal temperature, gas composition, particle size, particle concentration, and particle composition investigated, erosion of carbon steel is expected to be slower than 0.05 μm/h when the gas velocity in the convection section is less than approximately 8 m/s.

Electrical conductivity of p-type BiOCl nanosheets

2015 ◽  
Vol 51 (13) ◽  
pp. 2629-2632 ◽  
Author(s):  
Yoon Myung ◽  
Fei Wu ◽  
Sriya Banerjee ◽  
Jeunghee Park ◽  
Parag Banerjee
Keyword(s):  
Electrical Conductivity ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Electrical Conduction ◽  
Hydrolysis Method ◽  
P Type

BiOCl nanosheets were synthesized using a facile hydrolysis method and their p-type electrical conduction as a function of oxygen partial pressure was measured.

Electrical Conduction Properties of Liquid Vanadates. III. The System V2O5–Na2O–Fe2O3

1972 ◽  
Vol 50 (17) ◽  
pp. 2877-2881
Author(s):  
R. C. Kerby ◽  
J. R. Wilson
Keyword(s):  
Activation Energy ◽  
Vanadium Pentoxide ◽  
Electrical Conduction ◽  
Ferric Oxide ◽  
Conduction Mechanism ◽  
Ionic Conduction ◽  
Sodium Oxide ◽  
Electrical Conduction Mechanism ◽  
Partial Pressures ◽  
Electrical Conductivities

The liquid ferric vanadates exhibited n-type semiconduction properties at oxygen partial pressures greater than 0.1 atm. For ferric oxide concentrations less than 16 mol%, the activation energy of conduction was less than the activation energy associated with liquid vanadium pentoxide, but at greater ferric oxide concentrations, the activation energy increased to values greater than that associated with liquid vanadium pentoxide. The negative oxygen partial pressure coefficients of conduction were found to decrease with increasing ferric oxide concentration. The addition of sodium oxide to the liquid ferric vanadates decreased the activation energies of conduction. The electrical conductivities of these sodium ferric vanadates were found to be independent of oxygen partial pressure.The electrical conduction mechanism of the ferric vanadates was considered to involve the movement of delocalized electrons or polarons between V4+ and V5+ centers at low ferric oxide concentrations and the additional movement of delocalized electrons between Fe2+ and Fe3+ centers for ferric oxide concentrations greater than 16 mol%. The addition of sodium oxide to the liquid ferric vanadates apparently changed the electrical conduction mechanism from semiconduction to ionic conduction. Sodium and oxygen ions are probably the charge-carrying species in these ionic melts.

Electrical conduction in superconductive Nd2−xCexCuO4−y at high temperatures

1991 ◽  
Vol 6 (1) ◽  
pp. 42-45 ◽  
Author(s):  
Fumio Munakata ◽  
Takashi Kawano ◽  
Ayumi Nozaki ◽  
H. Yamauchi
Keyword(s):  
Electrical Resistivity ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Electrical Conduction ◽  
Pressure Dependence ◽  
Carrier Density ◽  
Oxygen Vacancies ◽  
Oxygen Deficiency ◽  
Charge Carriers ◽  
Partial Pressures

The temperature dependence of electrical resistivity of Nd2−xCexCuO4−y (x = 0.0, 0.1, 0.15, 0.18) was measured at oxygen partial pressures of 2.08 × 10−1 1.8 × 10−2, 8.1 × 10−4, and 3.3 × 10−6 atm. The oxygen-partial-pressure dependence of resistivity indicated that the charge carriers in Nd2−xCexCuO4−y were electrons. According to the resistivity data of these compounds at temperatures above 770 K, Ce doping affected the relation between the oxygen deficiency and oxygen partial pressure in Nd2CuO4−y: the doping of Ce worked to hinder the formation of oxygen vacancies in the lattice. Moreover, the carrier density after Ce doping was found to be much less than the value anticipated from the amount of the dopant. This suggested that not all the doped Ce ions worked as donors. That is, the relative amount of Ce3+ ions compared to that of Ce4+ ions increased as the total amount of the doped Ce ions increased.

Cupric Oxide Thin Films for Photovoltaic Applications

2013 ◽  
Vol 1538 ◽  
pp. 185-190
Author(s):  
Patrick J. M. Isherwood ◽  
Biancamaria Maniscalco ◽  
Fabiana Lisco ◽  
Piotr M. Kaminski ◽  
Jake W. Bowers ◽  
...  
Keyword(s):  
Thin Films ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Structural Properties ◽  
Cupric Oxide ◽  
Soda Lime ◽  
Soda Lime Glass ◽  
Oxide Thin Films ◽  
Glass Slides ◽  
Increasing Temperature

ABSTRACTCupric oxide thin films were sputtered onto soda-lime glass slides from a single pre-formed ceramic target using a radio-frequency power supply. The effects of oxygen partial pressure and substrate temperature on the optical, electrical and structural properties of the films were studied. It was found that increasing temperature resulted in increased crystallinity and crystal size but also increased film resistivity. The most conductive films were those deposited at room temperature. Increasing oxygen partial pressure was found to reduce resistivity dramatically. This is thought to be due to higher charge carrier concentrations resulting from increased copper vacancies. Increasing oxygen partial pressure causes an increase in the optical band gap from a minimum of 0.8eV up to a maximum of 1.42eV. Oxygen-rich films display reduced crystallinity, becoming increasingly amorphous with increased oxygen content. These results show that the optical, electrical and structural properties of sputtered cupric oxide films can be controlled by alteration of the deposition environment.

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