Examples of the Practical Use of Non-Stoichiometric Compounds

1994 ◽  
Author(s):  
Koji Kosuge
Keyword(s):  
Solid State ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Pressure ◽  
Closed System ◽  
Electromotive Force ◽  
Solid Electrolytes ◽  
Coulometric Titration ◽  
Preparation Methods ◽  
Basic Characteristics

In this chapter, we describe four kinds of non-stoichiometric compound, which are or will be in practical use, from the viewpoint of preparation methods or utility. As a first example, the solid electrolyte (ZrO2)0.85(CaO)0.15 is described, which are discussed in Sections 1.4.6–1.4.8 from the viewpoint of basic characteristics. The second example is the magnetic material Mn–Zn ferrite, for which the control of non-stoichiometry and the manufacturing process will be described. Then the metal hydrides or hydrogen absorbing alloys, which are one of the most promising materials for storing and transporting hydrogen in the solid state, are described, mainly focusing on the phase relation. Finally, we describe the relation between the control of composition and the growth of a single crystal of the semiconductive compound GaAs, which is expected to give electronic materials for 1C and LSI etc. Solid electrolytes, which show ionic conductivity in the solid state, are considered to be potential materials for practical use, some are already used as mentioned below. Solid electrolytes have characteristic functions, such as electromotive force, ion selective transmission, and ion omnipresence. Here we describe the practical use of calcia stabilized zirconia (CSZ), (ZrO2)0.85(CaO)0.15, the structure and basic properties of which are discussed in detail in Sections 1.4.5–1.4.8. The most simple practical application of CSZ is for the gauge of oxygen partial pressure, as mentioned in Sections 1.4.7 and 1.4.8. The oxygen partial pressure P2o2 in the closed system as shown in Fig. 3.1 can be measured, taking the air as the standard oxygen pressure P1o2. The electromotive force (EMF) of this concentration cell is expressed as . . . E = (RT/4F)ln(P1o2/ P2o2) . . . This principle is applied in the measurement of oxygen partial pressure in laboratory experiments and of the oxygen activity of slag in refineries. Based on the principle of coulometric titration (see Section 1.4.8), the oxygen partial pressure of a closed system can be kept constant by feedback of the EMF, in the oxygen pressure range 1 to 10−7 atm. By use of this closed system, investigations on redox reactions of metals and also enzyme reactions have been carried out.

Decrease in Resistance of Ceria Oxygen Sensor Induced by 10 mol% Hf and Zr Doping

2005 ◽  
Vol 888 ◽  
Author(s):  
Noriya Izu ◽  
Woosuck Shin ◽  
Ichiro Matsubara ◽  
Norimitsu Murayama
Keyword(s):  
Solid State ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Solid State Reaction ◽  
Pressure Range ◽  
Oxygen Sensor ◽  
Cubic Phase ◽  
Doped Ceria ◽  
Oxygen Gas ◽  
Resistive Type

ABSTRACTResistive type sensors using 10 mol% Hf-doped ceria and 10 mol% Zr-doped ceria, which had a single cubic phase obtained by solid state reaction, were fabricated and their sensing properties were investigated. The resistance and resistivity of the 10 mol% Hf-doped ceria or 10 mol% Zr-doped ceria were smaller than those of non-doped ceria. In the case of the same temperature of solid state reaction, the resistance and resistivity of the 10 mol% Hf-doped ceria were much smaller than those of the 10 mol% Zr-doped ceria. Furthermore, in the case of the same dopant, the resistance and resistivity of the sensor prepared from the solid state reaction at 1773 K were much smaller than those at 1673 K. The sensor using the 10 mol% Hf-doped ceria could be used as an oxygen gas sensor in wide oxygen partial pressure range and could be applicable to a λ sensor and a universal A/F sensor.

Controlled partial melting during isobaric and isothermal processing of dipcoated Bi-2212/Ag tapes

1998 ◽  
Vol 13 (12) ◽  
pp. 3580-3586 ◽  
Author(s):  
A. L. Crossley ◽  
J. L. MacManus-Driscoll
Keyword(s):  
Phase Diagram ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Partial Melting ◽  
Coulometric Titration ◽  
Processing Route ◽  
Optimum Processing ◽  
Partial Pressures ◽  
Titration Technique

A detailed study has been made of the control and optimization of partial melting of dipcoated Bi2Sr2Ca1Cu2O8+δAg0.1 (Bi-2212) tapes using reduced oxygen partial pressures. A coulometric titration technique has been employed to vary the oxygen partial pressure in a region of the phase diagram corresponding to binary melting, and the amount of partial melting has been quantified. Using this information, tapes have been processed using both isothermal and isobaric techniques. An optimum processing route was determined which combined isothermal and isobaric processes. Highly aligned material at the point of optimum melting was obtained.

Single Crystal Growth of YBa2Cu4O8 and Y2Ba4Cu7O15 Under High Oxygen Pressure

1991 ◽  
Vol 251 ◽  
Author(s):  
T. Miyatake ◽  
T. Takata ◽  
K. Yamaguchi ◽  
K. Takamuku ◽  
N. Koshizuka ◽  
...  
Keyword(s):  
Crystal Growth ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Single Crystal ◽  
Single Crystals ◽  
Oxygen Pressure ◽  
Maximum Size ◽  
Single Crystal Growth ◽  
Mixed Gas ◽  
High Oxygen Pressure

ABSTRACTWe investigate the crystal growth of YBa2Cu4O8 (124) and Y2Ba4Cu7O15 (247) in Al2O3 crucibles at an oxygen partial pressure of 20MPa employing an O2- HIP apparatus in a mixed gas environment of Ar-20%O2. Various melts compositions, rich in Ba and Cu, are explored to optimize crystal growth of 124. Large 124 single crystals up to a size of 1×0.5×0.05mm3 are obtained from compositions with about 65˜67%CuO. 247 single crystals having a maximum size of 3×1.5×0.05mm3 are grown from the same composition of melts. 124 crystals exhibit superconductivity at 75K. 247 crystals show Tc of 20K.

scholarly journals Effect of Oxygen Pressure on the Initial Oxidation Behavior of Cu and Cu-Au Alloys

2011 ◽  
Vol 1318 ◽  
Author(s):  
Langli Luo ◽  
Yihong Kang ◽  
Zhenyu Liu ◽  
Judith C Yang ◽  
Guangwen Zhou
Keyword(s):  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Pressure ◽  
Atomic Scale ◽  
Nucleation Theory ◽  
Nucleation Density ◽  
Atmospheric Conditions ◽  
Initial Oxidation ◽  
Effect Of Oxygen ◽  
Pure Cu

ABSTRACTA wide information gap exists between our present atomic-scale knowledge of metal oxidation derived from conventional ultrahigh vacuum (UHV) surface science experiments and the oxidation mechanisms obtained from the growth of bulk oxide thin films under technologically relevant realistic (or near-) atmospheric conditions. To bridge this pressure gap, we present an in-situ transmission electron microscopy (TEM) study of the initial oxidation stage of Cu(100) and Cu-Au(100) surfaces where the oxygen partial pressure varies from 5x10-4 to 150 Torr. For Cu(100), with increasing oxygen partial pressure (pO2), the nucleation density of the oxide islands increases and so does the growth rate of the oxide islands. As the pO2 continues to increase, a transition from epitaxial cube-on-cube Cu2O islands to randomly oriented oxide islands is observed. A kinetic model based on the classic heterogeneous nucleation theory is developed to explain the effect of oxygen partial pressure on the oxide orientation. It is shown that such a transition in the oxide nucleation orientation is related to the effect of oxygen pressure on the nucleation barrier and atom collision rate. The Cu-Au(111) alloy revealed the same oxygen pressure dependency of the oxide nucleation orientation as pure Cu oxidation.

High temperature X-ray diffraction studies of the decomposition mechanism of YBa2Cu3O7−δ at an oxygen partial pressure less than 10 Pa

1995 ◽  
Vol 10 (3) ◽  
pp. 165-169 ◽  
Author(s):  
W. Pitschke ◽  
W. Bieger ◽  
G. Krabbes ◽  
U. Wiesner
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Solid State Reaction ◽  
Peritectic Reaction ◽  
Decomposition Reaction ◽  
Primary Decomposition ◽  
X Ray Diffraction ◽  
X Ray

The crystallographic data of YBa2Cu3O7−δ, Y2BaCuO5, BaCu2O2, and YBa4Cu3O9 at high temperatures and p(O2)<10 Pa have been derived on the basis of HT-XRD measurements. Whereas Y2BaCuO5 expands nearly isotropically, YBa2Cu3O7−δ and BaCu2O2 show anisotropic expansions. Furthermore, the first decomposition step of the considered compounds at p(O2)<10 Pa was observed. BaCu2O2 melts congruently at T ≍ 1273 K and Y2BaCuO5 decomposes via a peritectic reaction into Y2O3, Y2BaO4 and melts at T ≍ 1323 K. A solid-state reaction into Y2BaCuO5 and BaCu2O2 was indicated for YBa2Cu3O7−δ at T ≍ 1123 K. Because YBa4Cu3O9 becomes unstable at T ≍ 1123 K, this compound cannot be formed by the primary decomposition reaction of YBa2Cu3O7−δ

scholarly journals Garnet-type solid electrolyte: Advances of ionic transport performance and its application in all-solid-state batteries

2021 ◽  
Author(s):  
P. M. Gonzalez Puente ◽  
Shangbin Song ◽  
Shiyu Cao ◽  
Leana Ziwen Rannalter ◽  
Ziwen Pan ◽  
...  
Keyword(s):  
Solid State ◽  
Solid Electrolyte ◽  
Solid Electrolytes ◽  
High Energy ◽  
Environmental Stability ◽  
Preparation Methods ◽  
Metal Anode ◽  
Safety Issues ◽  
Electrochemical Window ◽  
Increasing Demand

AbstractAll-solid-state lithium batteries (ASSLBs), which use solid electrolytes instead of liquid ones, have become a hot research topic due to their high energy and power density, ability to solve battery safety issues, and capabilities to fulfill the increasing demand for energy storage in electric vehicles and smart grid applications. Garnet-type solid electrolytes have attracted considerable interest as they meet all the properties of an ideal solid electrolyte for ASSLBs. The garnet-type Li7La3Zr2O12 (LLZO) has excellent environmental stability; experiments and computational analyses showed that this solid electrolyte has a high lithium (Li) ionic conductivity (10−4–10−3 S·cm−1), an electrochemical window as wide as 6 V, stability against Li metal anode, and compatibility with most of the cathode materials. In this review, we present the fundamentals of garnet-type solid electrolytes, preparation methods, air stability, some strategies for improving the conductivity based on experimental and computational results, interfacial issues, and finally applications and challenges for future developments of LLZO solid electrolytes for ASSLBs.

scholarly journals Oxygen supply capacity in animals evolves to meet maximum demand at the current oxygen partial pressure regardless of size or temperature

2019 ◽  
Author(s):  
Brad A. Seibel ◽  
Curtis Deutsch
Keyword(s):  
Metabolic Rate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Pressure ◽  
Thermal Tolerance ◽  
Oxygen Supply ◽  
Cardiovascular Health ◽  
Hypoxia Tolerance ◽  
Aerobic Scope ◽  
Supply Capacity

AbstractPhysiological oxygen supply capacity is associated with athletic performance and cardiovascular health and is thought to cause hypometabolic scaling in diverse species. Environmental oxygen is widely believed to be limiting of metabolic rate and aerobic scope, setting thermal tolerance and body size limits with implications for species diversity and biogeography. Here we derive a quantifiable linkage between maximum and basal metabolic rate and their temperature, size and oxygen dependencies. We show that, regardless of size or temperature, the capacity for oxygen supply precisely matches the maximum evolved demand at the highest persistently available oxygen pressure which, for most species assessed, is the current atmospheric pressure. Any reduction in oxygen partial pressure from current values will result in a decrement in maximum metabolic performance. However, oxygen supply capacity does not constrain thermal tolerance and does not cause hypometabolic scaling. The critical oxygen pressure, typically viewed as an indicator of hypoxia tolerance, instead reflects adaptations for aerobic scope. This simple new relationship redefines many important physiological concepts and alters their ecological interpretation.One sentence summary: Metabolism is not oxygen limited

The Effects of Solvent and Oxygen Pressure on the Autoxidation of Benzoin Catalysed by Nickel Acetate

1979 ◽  
Vol 32 (2) ◽  
pp. 421 ◽  
Author(s):  
RP Chaplin ◽  
S Vorlow ◽  
MS Wainwright
Keyword(s):  
Free Radical ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Oxygen Pressure ◽  
Second Order ◽  
Nickel Acetate ◽  
Coordination Complex ◽  
First Order ◽  
First Order Kinetics

Kinetic results are reported for the autoxidation of benzoin, catalysed by nickel acetate in methanol and ethanol. The reaction in methanol is first order with respect to benzoin and the catalyst and is independent of the oxygen partial pressure. The reaction is non-free-radical and probably involves a coordination complex between the substrate and the catalyst. In ethanol the reaction is found to obey second-order reversible kinetics with respect to benzoin and first-order kinetics with respect to the catalyst. The oxidation is also at least 10 times faster in ethanol than in methanol at 303 K.

Heavily donor-doped, optically translucent ferroelectric barium titanate ceramics through defect chemical engineering

CrystEngComm ◽  
2019 ◽  
Vol 21 (18) ◽  
pp. 2854-2862 ◽  
Author(s):  
Christian Pithan ◽  
Hayato Katsu ◽  
Rainer Waser
Keyword(s):  
Solid State ◽  
Barium Titanate ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Chemical Engineering ◽  
Ceramic Processing ◽  
Solid State Route ◽  
Titanate Ceramics ◽  
Conventional Ceramic Processing

The possibility of preparing translucent ferroelectric heavily donor-doped BaTiO3 ceramics rich in TiO2 has been demonstrated by conventional ceramic processing based on the synthesis via the solid state route and on subsequent sintering and annealing at high levels of oxygen partial pressure.

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