Stabilizing the ferroelectric phase in HfO2-based films sputtered from ceramic targets under ambient oxygen

Nanoscale ◽  
2021 ◽  
Author(s):  
Terence Mittmann ◽  
Michail Michailow ◽  
Patrick D. Lomenzo ◽  
Jan Gärtner ◽  
Max Falkowski ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Zirconium Oxide ◽  
Ferroelectric Phase ◽  
Ferroelectric Properties ◽  
Ambient Oxygen ◽  
Oxide Concentration ◽  
Ceramic Targets

The interplay of oxygen concentration and zirconium oxide concentration in thin HfxZr1−xO2 films significantly determines the phase and ferroelectric properties.

Zirconium – Based Ceramic Targets for Producing Nanocrystalline Coatings Resistant to Heat and Thermal Creep

2010 ◽  
Vol 11 ◽  
pp. 89-94 ◽  
Author(s):  
Andrzej Roman Olszyna ◽  
Marek Kostecki
Keyword(s):  
Phase Stability ◽  
Zirconium Oxide ◽  
Chemical Structure ◽  
Type A ◽  
High Density ◽  
Thermal Barrier ◽  
Zro2 Powder ◽  
Nano Crystalline ◽  
Alternative Materials ◽  
Ceramic Targets

Technology of thermal ceramic barriers (TBC) has been chiefly designed for materials with a single thermal barrier of the 7YSZ type. A high content of Y2O3 ensures a good phase stability of the YSZ material. In search for other alternative materials suitable for TBC, the material most often examined is modified zirconium oxide. The modification consists of stabilizing the ZrO2 powder with Y2O3 and doping it with La, Gd and Nd. This paper presents the results of studies on producing cathodic zirconium oxide-based ceramic targets intended for depositing refractory heat-resistant nano-crystalline TBC coatings. The targets are characterized by a high density (close to its theoretical value) and have a homogeneous phase and chemical structure.

Effects of Ambient Temperature and Oxygen Concentration on Soot Evolution in Diesel Spray Combustion

Volume 4 ◽  
2004 ◽  
Author(s):  
Yi Xu ◽  
Chia-Fon F. Lee
Keyword(s):  
Ambient Temperature ◽  
Heat Release ◽  
Oxygen Concentration ◽  
Heat Release Rate ◽  
Release Rate ◽  
Soot Formation ◽  
Premixed Combustion ◽  
Ambient Oxygen ◽  
Lower Heat ◽  
Soot Measurement

A newly developed Forward Illumination Light Extinction (FILE) soot measurement technique was applied in a constant volume spray chamber to study the effects of ambient temperature and oxygen concentration on soot evolution in diesel combustion. The FILE technique with the capability of two-dimensional time-resolved quantitative soot measurement provides the much-needed information to investigate the soot formation mechanism. The ambient temperatures of 1200K, 1000K and 800K were tested to study the temperature effects on soot formation. A decrease of ambient temperature results in a longer ignition delay, which promotes a larger premixed combustion zone combining with higher heat release rates. The change of ambient temperature from 1200K to 800K increases the fuel portion burnt in the premixed combustion period. At 800K, combustion is dominated by the premixed combustion and much less soot is formed. Diesel combustion with 21% and 15% ambient oxygen concentration was also studied. With lower ambient oxygen concentration, the combustion process is basically not changed, but expands into a longer time span with a lower heat release rate. The lower heat release rate results in a lower flame temperature, which benefits the NOx emission control. However, with about the same amount of soot within the flame, and much longer soot life, soot has more chance to escape to the exhaust.

Influence of some factors on oxygen uptake of canine cardiac Purkinje fibers

1963 ◽  
Vol 204 (1) ◽  
pp. 5-8 ◽  
Author(s):  
Kalman Greenspan ◽  
Paul F. Cranefield
Keyword(s):  
Oxygen Uptake ◽  
Oxygen Concentration ◽  
Diffusion Limitation ◽  
Purkinje Fibers ◽  
Ambient Oxygen ◽  
Cardiac Purkinje Fibers ◽  
Lower Oxygen ◽  
Wet Weight ◽  
Oxygen Tensions ◽  
Oxygen Concentrations

The rate of oxygen uptake of quiescent Purkinje fibers of the dog's heart was determined using a flow respirometer and oxygen polarography. At ambient oxygen concentrations of 60% or higher the rate of uptake was 0.739 mm3/mg wet weight per hr at 35 C. The temperature coefficient over the range 25–35° was 2.3. The uptake was independent of the ambient oxygen concentration at oxygen concentrations equal to or greater than 60% of an atmosphere. In lower oxygen concentrations the rate of uptake was found to be depressed. The depression of uptake in the lower oxygen tensions is probably the result of diffusion limitation; it may, however, reflect dependence of resting uptake on oxygen concentration.

Effects of ambient oxygen concentration on biodiesel and diesel spray combustion under simulated engine conditions

Energy ◽  
2013 ◽  
Vol 57 ◽  
pp. 722-732 ◽  
Author(s):  
Ji Zhang ◽  
Wei Jing ◽  
William L. Roberts ◽  
Tiegang Fang
Keyword(s):  
Oxygen Concentration ◽  
Diesel Spray ◽  
Spray Combustion ◽  
Ambient Oxygen

Investigation of Ferroelectric Properties of Vinylidene Fluoride Oligomer Evaporated Films

2002 ◽  
Vol 748 ◽  
Author(s):  
K. Noda ◽  
K. Ishida ◽  
K. Mochizuki ◽  
A. Kubono ◽  
T. Horiuchi ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Vinylidene Fluoride ◽  
Ferroelectric Phase ◽  
Ferroelectric Properties ◽  
Liquid Nitrogen Temperature ◽  
Polarization Reversal ◽  
Phase Form ◽  
Atomic Force ◽  
Oriented Parallel ◽  
Substrate Surfaces

ABSTRACTStructures and electrical properties of newly synthesized vinylidene fluoride (VDF) oligomer [CF3(CH2CF2)17I] films evaporated onto various substrates around liquid nitrogen temperature were investigated. As a result, the VDF oligomer films were mainly formed with ferroelectric phase (form I) crystals and the molecular chains were oriented parallel to the substrate surfaces regardless of both the kind of the substrates and the thickness of the VDF oligomer films. In addition to these properties, the VDF oligomer films showed polarization reversal due to 180° rotation of the polar VDF oligomer molecules according to the applied voltages. This ferroelectric behavior was verified by local poling and piezoresponse measurements with an atomic force microscope, and by measurements of D-E hysteresis curves.

Piezoelectric and Ferroelectric Properties of KNbO3 Added Bi0.5Na0.5TiO3 Ceramics

2017 ◽  
Vol 751 ◽  
pp. 384-389 ◽  
Author(s):  
Puripat Kantha ◽  
Phathaitep Raksa ◽  
Muangjai Unruan ◽  
Tawee Tunkasiri ◽  
Panupong Jaiban ◽  
...  
Keyword(s):  
Mixed Oxide ◽  
Room Temperature ◽  
Ferroelectric Phase ◽  
Ferroelectric Properties ◽  
Lead Free ◽  
Piezoelectric Response ◽  
Rhombohedral Structure ◽  
Rhombohedral Symmetry

The fabrication of lead-free (1-x)Bi0.5Na0.5TiO3 - xKNbO3 or (1-x)BNT-xKN ceramics where x = 0.00, 0.05, 0.10, and 0.15 was carried out by the modified two-step mixed oxide method. The effects of KNbO3 on structure, piezoelectric and ferroelectric properties were systematically investigated. XRD results revealed that the (1-x)BNT-xKN ceramics with low KN content of x less than 0.05 contained ferroelectric phase with a rhombohedral symmetry while the ceramics with x = 0.05 possessed pseudocubic structure. The higher KN content (x ≥ 0.10) ceramics had symmetries rhombohedral structure. At room temperature, the highest Pr and low Ec were obtained when the composition of x = 0.05. Moreover, the results showed the moderate KN addition could enhance the piezoelectric response. The d33 of 0.95BNT-0.05KN reached as high as 125 pC/N.

Comparative Study on Spray Auto-Ignition of Di-n-Butyl Ether and Diesel Blends at Engine-Like Conditions

2020 ◽  
Vol 143 (4) ◽  
Author(s):  
Yuanhang Guan ◽  
Wang Liu ◽  
Dong Han
Keyword(s):  
Heat Release ◽  
Oxygen Concentration ◽  
Pressure Rise ◽  
Fuel Spray ◽  
Release Rates ◽  
Butyl Ether ◽  
Auto Ignition ◽  
Ambient Oxygen ◽  
Ignition And Combustion ◽  
Oxygen Concentrations

Abstract Di-n-butyl ether (DBE), a promising lignocellulosic biofuel, has been suggested as a potential alternative fuel for compression ignition engines. In this study, the spray auto-ignition characteristics of diesel/DBE blends were experimentally measured on a constant volume combustion chamber. Time-resolved pressure traces and heat release rates in fuel spray combustion were measured at changed fuel blending fractions, ambient temperatures, and oxygen concentrations. Further, ignition delay and combustion delay that evaluates fuel spray ignition tendency were derived and compared for different test blends. Experimental results indicated that fuel spray ignition tendency is promoted with DBE addition, evidenced by the advanced pressure rise and heat release processes, and the shortened ignition and combustion delays. Peak heat release rates are fuel-dependent at high ambient oxygen concentrations since the relative fractions of the premixed and diffusive burns alter with changed DBE addition. However, as the oxygen concentration drops to 11%, fuel effects on the peak heat release rates become less noticeable. Reduced ambient oxygen concentration effectively extends fuel ignition and combustion delays, and typical two-stage pressure rises and heat releases are observed for all test blends, as the oxygen concentration drops to 11%.

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