High Resistivity GaSb and GaAs Produced by MBE Growth at Elevated Temperatures

1992 ◽  
Vol 262 ◽  
Author(s):  
A. Y. Polyakov ◽  
A. G. Milnes ◽  
M. Stam ◽  
R. G. Wilson ◽  
Z. Q. Fang ◽  
...  
Keyword(s):  
High Temperature ◽  
Hall Effect ◽  
High Temperatures ◽  
Strong Evidence ◽  
Elevated Temperatures ◽  
Schottky Barriers ◽  
High Resistivity ◽  
Epitaxial Layers ◽  
Mbe Growth ◽  
Resistivity Profiling

ABSTRACTIn this paper we show that when grown by MBE at unusually high temperatures epitaxial layers of GaSb and GaAs are semi-insulating. In GaSb combination of Hall effect, TSC, SIMS and two probe resistivity profiling leads us to believe that high resistivity is due to production of midgap centers at elevated temperatures. No strong evidence of the prevalence of such midgap centers was obtained for high temperature GaAs layers and in this case we believe that high resistivity is associated with the formation of Ga-related precipitates acting as internal Schottky barriers.

scholarly journals High temperature ultrasonic sensor for fission gas characterization in MTR harsh environment

2018 ◽  
Vol 170 ◽  
pp. 04008
Author(s):  
O. Gatsa ◽  
P. Combette ◽  
E. Rozenkrantz ◽  
D. Fourmentel ◽  
C. Destouches ◽  
...  
Keyword(s):  
High Temperature ◽  
Thick Film ◽  
Screen Printing ◽  
Bismuth Titanate ◽  
Elevated Temperatures ◽  
Ultrasonic Sensor ◽  
High Resistivity ◽  
Materials Testing ◽  
Coupling Coefficients ◽  
Film Fabrication

In the contemporary world, the measurements in hostile environment is one of the predominant necessity for automotive, aerospace, metallurgy and nuclear plant. The measurement of different parameters in experimental reactors is an important point in nuclear power strategy. In the near past, IES (Institut d’Électronique et des Systèmes) on collaboration with CEA (Commissariat à l’Energie Atomique et aux Energies Alternatives) have developed the first ultrasonic sensor for the application of gas quantity determination that has been tested in a Materials Testing Reactor (MTR). Modern requirements state to labor with the materials that possess stability on its parameters around 350°C in operation temperature. Previous work on PZT components elaboration by screen printing method established the new basis in thick film fabrication and characterization in our laboratory. Our trials on Bismuth Titanate ceramics showed the difficulties related to high electrical conductivity of fabricated samples that postponed further research on this material. Among piezoceramics, the requirements on finding an alternative solution on ceramics that might be easily polarized and fabricated by screen printing approach were resolved by the fabrication of thick film from Sodium Bismuth Titanate (NBT) piezoelectric powder. This material exhibits high Curie temperature, relatively good piezoelectric and coupling coefficients, and it stands to be a good solution for the anticipated application. In this paper, we present NBT thick film fabrication by screen printing, characterization of piezoelectric, dielectric properties and material parameters studies in dependence of temperature. Relatively high resistivity in the range of 1.1013 Ohm.cm for fabricated thick film is explained by Aurivillius structure in which a-and b-layers form perovskite structure between oxides of c-layer. Main results of this study are presented and discussed in terms of feasibility for an application to a new sensor device operating at high temperature level (400°). Piezoelectric parameters enhancement and loss reduction at elevated temperatures are envisaged to be optimized. Further sensor development and test in MTR are expected to be realized in the near future.

High temperature mechanical properties of steel bars available in Pakistan

2018 ◽  
Vol 9 (3) ◽  
pp. 203-221 ◽  
Author(s):  
Muhammad Masood Rafi ◽  
Abdul Basit Dahar ◽  
Tariq Aziz
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Ambient Temperature ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Experimental Testing ◽  
Local Market ◽  
Content Type ◽  
Yield Plateau ◽  
Steel Bars

Purpose The purpose of this paper is to present the results of experimental testing of steel rebars at elevated temperatures. Three types of bars available in the local market in Pakistan were used. These data are not available in Pakistan. Design/methodology/approach Three types of bars were used, which included cold-twisted ribbed (CTR), hot-rolled deformed (HRD) and thermo-mechanically treated (TMT) bars. The diameter of the bar of each type was 16 mm. The bars were heated in an electrical furnace at temperatures which were varied from 100°C to 900°C in increment of 100°C. Bars of each type were also tested at ambient temperature as control specimens. The change of strength, strain and modulus of elasticity of the bars at high temperatures were determined. Findings The mechanical properties of the bars were nearly unaffected by the temperatures up to 200°C. CTR bars did not show yield plateau and strain hardening both at ambient and high temperatures. The high temperature yield strength and elastic modulus for all the three types of bars were similar at all temperatures. The yield plateau of both the HRD and TMT bars disappeared at temperatures greater than 300°C. The ultimate strength at high temperature of the HRD and TMT bars was also similar. The behaviours of the HRD and TMT bars changed to brittle beyond 400°C as compared to their behaviours at ambient temperature. The CTR bars exhibited ductile characteristics at failure at all the exposure temperatures relative to their behaviour at ambient temperature. Research limitations/implications The parameters of the paper included the rebar type and heating temperature and the effects of temperature on strength and stiffness properties of the steel bars. Practical implications Building fire incidents have increased in Pakistan. As reinforced concrete (RC) buildings exist in the country in significant numbers, the data related to elevated temperature properties of steel is required. These data are not available in Pakistan presently. The presented paper aims at providing this information for the design engineers to enable them to assess and increase fire resistance of RC structural members. Originality/value The presented paper is unique in its nature in that there is no published contribution to date, to the best of authors’ knowledge, which has been carried out to assess the temperature-dependent mechanical properties of steel reinforcing bars available in Pakistan.

scholarly journals Improving the Thermal Stability of Hydrophobic Associative Polymer Aqueous Solution Using a “Triple-Protection” Strategy

Polymers ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 949 ◽  
Author(s):  
Bo Yang ◽  
Jincheng Mao ◽  
Jinzhou Zhao ◽  
Yang Shao ◽  
Yang Zhang ◽  
...  
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Polymer Network ◽  
Crosslinking Agent ◽  
Water Soluble ◽  
Fluid Viscosity ◽  
Fracturing Fluid ◽  
Temperature Resistance ◽  
Protection Strategy

Because of their high viscoelasticity, Hydrophobic Associative Water-Soluble Polymers (HAWSPs) have been widely used in many industrial fields, especially in oilfield flooding and fracturing. However, one major problem which limits the wide applications of HAWSPs is their weak resistance to high temperatures. Once the temperature increases over 100 °C, the viscosity of the fracturing fluid decreases rapidly, because high temperatures reduce fluid viscosity by oxidizing the polyacrylamide chains and weakening the association of hydrophobic groups. To improve the high temperature resistance of one HAWSP, a triple-protection strategy was developed. First, rigid N-vinyl-2-pyrrolidone moiety was introduced into the polymer chains. Second, an environmentally-friendly deoxidizer, carbohydrazide, was selected to prevent polymer oxidization by scavenging dissolved oxygen. Results showed that both the rigid groups and the deoxidizer improved the temperature resistance of the polymer and helped it maintain high viscosity under high temperature and shear rate. Using these two protection strategies, the resistant temperature of the polymer could reach 160 °C. However, the polymer network still got severely damaged at further elevated temperatures. Therefore, as the third protection strategy, the pre-added high temperature responsive crosslinking agent was applied to form new networks at elevated temperatures. The results have shown that the optimized polymer solution as a kind of fracturing fluid showed good temperature resistance up to 200 °C.

Directionally Solidified Ceramic Eutectics for High-Temperature Applications

2013 ◽  
pp. 303-322 ◽  
Author(s):  
Iurii Bogomol ◽  
Petro Loboda
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Eutectic Point ◽  
Eutectic Microstructure ◽  
Directionally Solidified ◽  
Microstructure Parameters ◽  
Directionally Solidified Eutectics ◽  
Temperature Applications

The processing techniques, microstructures, and mechanical properties of directionally solidified eutectic ceramics are reviewed. It is considered the main methods for preparing of eutectic ceramics and the relationships between thermal gradient, growth rate, and microstructure parameters. Some principles of coupled eutectic growth, main types of eutectic microstructure and the relationship between the eutectic microstructure and the mechanical properties of directionally solidified eutectics at ambient and high temperatures are briefly described. The mechanical behavior and main toughening mechanisms of these materials in a wide temperature range are discussed. It is shown that the strength at high temperatures mainly depends on the plasticity of the phase components. By analyzing the dislocation structure, the occurrence of strain hardening in single crystalline phases during high-temperature deformation is revealed. The creep resistance of eutectic composites is superior to that of the sintered samples due to the absence of glassy phases at the interfaces, and the strain has to be accommodated by plastic deformation within the domains rather than by interfacial sliding. The microstructural and chemical stability of the directionally solidified eutectic ceramics at high temperatures are discussed. The aligned eutectic microstructures show limited phase coarsening up to the eutectic point and excellent chemical resistance. Directionally solidified eutectics, especially oxides, revealed an excellent oxidation resistance at elevated temperatures. It is shown sufficient potential of these materials for high-temperature applications.

Application of modified starch in high-temperature-resistant colloidal gas aphron (CGA) drilling fluids

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Wenxi Zhu ◽  
Xiuhua Zheng
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
High Performance ◽  
Oil And Gas ◽  
Elevated Temperatures ◽  
Drilling Fluid ◽  
Drilling Fluids ◽  
Modified Starch ◽  
Gas Reservoirs ◽  
Building Capability

Abstract Colloidal gas aphrons (CGA) are finding increasing application in depleted oil and gas reservoirs because of their distinctive characteristics. To overcome the limitations of its application in high-temperature drilling, a modified starch foams stabilizer WST with a temperature resistance of 160 °C was synthesized via radical polymerization. The chemical structure of WST was characterized by Fourier infrared spectroscopy and results showed that all three monomers acrylamide, 2-acrylamido-2-methyl-1-propane sulfonic acid, and N-vinylpyrrolidone have been grafted onto starch efficiently. Based on the microscopic observations, highly stable aphrons have been successfully generated in the WST-based CGA drilling fluids within 160 °C, and most aphrons lie in the range of 10–150 μm. WST can provide higher viscosity at high temperatures compared to xanthan gum, which helps to extend foam life and stability by enhancing the film strength and slowing down the gravity drainage. Results show that WST-CGA aged at elevated temperatures (120–160 °C) is a high-performance drilling fluid with excellent shear-thinning behavior, cutting carrying capacity, and filtration control ability. The significant improvement of filtration control and well-building capability at high temperatures is an important advantage of WST-CGA, which can be attributed to the enhancement of mud cake quality by WST.

A Modified Spinning Drop Method for High-Temperature Applications

1983 ◽  
Vol 23 (01) ◽  
pp. 155-156 ◽  
Author(s):  
Lyman L. Handy ◽  
Mokhtar El-Gassier ◽  
Iraj Ershaghi
Keyword(s):  
High Temperature ◽  
Crude Oil ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Mineral Oil ◽  
High Temperature Application ◽  
Capillary Tubes ◽  
Drop Method ◽  
Tension Properties ◽  
Temperature Application

Abstract The spinning drop apparatus has been modified to measure interfacial tensions (IFT) at elevated pressures and temperatures. Interfacial tension properties of various surfactant solutions against a mineral oil and a California crude oil have been measured at elevated temperatures with this equipment. The surfactants included TRS 10–80, Igepal DM-730 and Petro step 465. The IFT of Igepal DM-730 against the crude oil shows a minimum at a temperature of 95°C and at a surfactant concentration of 5 g/l in a 10 g/l NaCl solution. With the same crude oil, Petro step 465 shows no temperature effect and the minimum IFT is obtained at a surfactant concentration of 2 g/l and a NaCl concentration of 10 g/l. The TRS 10–80 shows a somewhat similar behavior with respect to temperature, but the minimum IFT's and the corresponding salt and surfactanat concentrations to obtain them are different. Introduction The application of surfactant systems at elevated temperature has been the subject of several studies. Handy et al. described various aspects of usingsurfactants as additives in steam flooding. 1 In this application, the interfacial tension properties of surfactant-crude oil systems must beevaluated at elevated temperatures. Furthermore, data on the temperature dependence of the IFT of surfactants versus crude oil will be pertinent to careful design of chemical floods for reservoir temperatures above 100°C. Two methods for measuring IFT properties of surfactant-oil systems have been described in the literature, the pendent drop and the spinning drop methods. The pendent drop method, developed by Andreas, Hauser, and Tucker2, has been modified for high pressure application by Harvey3 and for high temperature and pressure by Jennings4. Systems studied by these modified instruments have beenin IFT ranges significantly above the ultra-low IFT's required for improvingoil displacement with surfactants. The spinning drop method discussed byVannegut5, Silberberg6, Rosenthal7, Princen etal.8 was recently developed by Caylas et al.9 The proposed design included the capability for variable speed tensiometry. Gashand Parrish10 introduced a fixed speed spinning drop tensiometer and reported satisfactory results at a speed of 3600 RPM. No work has yet beenreported on the extension of the design of the spinning drop method for use at high temperatures. In this study, problems associated with high temperature application of the spinning drop method were considered. The equipment was modified to extend the operation of a fixed speed system to temperatures up to 250°C. The modified quipment was used to study the IFT behavior of three surfactants versus a crude oil and one surfactant versus a mineral oil. Apparatus A constant speed (3600 RPM) spinning drop apparatus was modified for high temperature application by addition of a temperature air bath and the development of a technique for sealing the fluids within the capillary tubes to withstand high temperatures and pressures. As shown in Fig. 1, the capillarytubes operate within the air bath (A) made of a 3/4" thick Marinite mix (anasbestos-free insulator) with a capability of maintaining the temperature as high as 600°C (~1100°F). Vanes (B) placed inside the air bath were intended to maintain uniform temperature throughout the system. Temperature was measured beside the capillary tubes (E) using J type thermocouples (F) and read on a digital recorder (G). The fluid content within the capillaries must be contained at high temperatures and pressures. The open end of the capillary tubes were sealed with a high temperature epoxy, Fig. 2. The epoxy hardens quickly and is capable of withstanding pressures up to 5.9 MPa. The epoxy seal can easily be drilled out to permit the re-use of the tubes.

Investigation of the Effects of High Temperature Aging on the Mechanical Behavior of Lead Free Solders

2018 ◽  
Author(s):  
Mohammad S. Alam ◽  
K. M. Rafidh Hassan ◽  
Jeffrey C. Suhling ◽  
Pradeep Lall
Keyword(s):  
Mechanical Properties ◽  
High Temperature ◽  
Mechanical Behavior ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Lead Free ◽  
Specimen Preparation ◽  
Stress Strain ◽  
Initial Modulus ◽  
Lead Free Solders

Lead free solders are renowned as interconnects in electronic packaging due to their relatively high melting point, attractive mechanical properties, thermal cycling reliability, and environment friendly chemical properties. The mechanical behavior of lead free solders is highly dependent on the operating temperature. Previous investigations on mechanical characterization of lead free solders have mainly emphasized stress-strain and creep testing at temperatures up to 125 °C. However, electronic devices, sometimes, experience harsh environment applications including well drilling, geothermal energy, automotive power electronics, and aerospace engines where solders are exposed to very high temperatures from 125–200 °C. Mechanical properties of lead free solders at elevated temperatures are limited. In this work, we have investigated the mechanical behavior SAC305 (96.5Sn-3.0Ag-0.5Cu) and SAC_Q (SAC+Bi) lead free solders at extreme high temperatures up to 200 °C. Stress-strain tests were performed on reflowed uniaxial specimens at four elevated temperatures (T = 125, 150, 175, and 200 °C). In addition, changes of the mechanical behavior of these alloys due to isothermal aging at T = 125 °C have been studied. Extreme care has been taken during specimen preparation so that the fabricated solder uniaxial test specimens accurately reflect the solder material microstructures present in actual lead free solder joints. High temperature tensile properties of the solders including initial modulus, yield stress, and ultimate tensile strength have been compared. As expected, our results show substantial degradations of the mechanical properties of lead-free solders at higher temperatures. With prior aging, these degradations become even more significant. Comparison of the results has shown that the addition of Bi to traditional SAC alloys improves their high temperature properties and significantly reduces their aging induced degradations.

scholarly journals A plant reovirus hijacks endoplasmic reticulum-associated degradation machinery to promote efficient viral transmission by its planthopper vector under high temperature conditions

2021 ◽  
Vol 17 (3) ◽  
pp. e1009347
Author(s):  
Xiangzhen Yu ◽  
Dongsheng Jia ◽  
Zhen Wang ◽  
Guangjun Li ◽  
Manni Chen ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
High Temperature ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Protein Quality ◽  
Southern China ◽  
Nonstructural Protein ◽  
Viral Transmission ◽  
Endoplasmic Reticulum Associated Degradation ◽  
Er Membrane

In the field, many insect-borne crop viral diseases are more suitable for maintenance and spread in hot-temperature areas, but the mechanism remains poorly understood. The epidemic of a planthopper (Sogatella furcifera)-transmitted rice reovirus (southern rice black-streaked dwarf virus, SRBSDV) is geographically restricted to southern China and northern Vietnam with year-round hot temperatures. Here, we reported that two factors of endoplasmic reticulum-associated degradation (ERAD) machinery, the heat shock protein DnaJB11 and ER membrane protein BAP31, were activated by viral infection to mediate the adaptation of S. furcifera to high temperatures. Infection and transmission efficiencies of SRBSDV by S. furcifera increased with the elevated temperatures. We observed that high temperature (35°C) was beneficial for the assembly of virus-containing tubular structures formed by nonstructural protein P7-1 of SRBSDV, which facilitates efficient viral transmission by S. furcifera. Both DnaJB11 and BAP31 competed to directly bind to the tubule protein P7-1 of SRBSDV; however, DnaJB11 promoted whereas BAP31 inhibited P7-1 tubule assembly at the ER membrane. Furthermore, the binding affinity of DnaJB11 with P7-1 was stronger than that of BAP31 with P7-1. We also revealed that BAP31 negatively regulated DnaJB11 expression through their direct interaction. High temperatures could significantly upregulate DnaJB11 expression but inhibit BAP31 expression, thereby strongly facilitating the assembly of abundant P7-1 tubules. Taken together, we showed that a new temperature-dependent protein quality control pathway in the ERAD machinery has evolved for strong activation of DnaJB11 for benefiting P7-1 tubules assembly to support efficient transmission of SRBSDV in high temperatures. We thus deduced that ERAD machinery has been hitchhiked by insect-borne crop viruses to enhance their transmission in tropical climates.

Simultaneous Implant Activation and Isolation Formation in GaAs in a Single High-Temperature Anneal

1992 ◽  
Vol 262 ◽  
Author(s):  
Kei-Yu Ko ◽  
S. Chen ◽  
G. Braunstein ◽  
L.-R. Zheng ◽  
S.-T. Lee
Keyword(s):  
Thermal Stability ◽  
High Temperature ◽  
High Temperatures ◽  
Active Regions ◽  
High Resistivity ◽  
Thermally Stable ◽  
Electrical Isolation ◽  
Device Processing ◽  
High Temperature Anneal ◽  
Thermal Stability Of

ABSTRACTUsing void-related compensation in Al-implanted GaAs, high-resistivity isolation regions that are thermally stable to high temperatures (> 700 °C) are demonstrated. The high-temperature thermal stability of the isolation regions allows the simplification of device processing in which a single high-temperature anneal (e.g., at 900 °C) can be used to activate the implant dopants in the device-active regions, and simultaneously to convert the Al-implanted regions highly resistive for electrical isolation. Other advantages of using void-related isolation will also be discussed.

scholarly journals Ethephon Treatment May Alleviate the Suppression of Female Flowers of Cucurbita Pepo under High Temperatures

HortScience ◽  
2006 ◽  
Vol 41 (6) ◽  
pp. 1421-1422 ◽  
Author(s):  
H.C. Wien
Keyword(s):  
High Temperature ◽  
High Temperatures ◽  
Elevated Temperatures ◽  
Female Flower ◽  
Flower Buds ◽  
Flower Bud ◽  
Ethylene Action ◽  
Ethephon Treatment ◽  
Flower Bud Formation ◽  
Female Flowers

When pumpkins are grown in elevated temperatures (32/27 °C day/night) for 1 week during flower development, fewer female flower buds are formed than at normal temperatures (20/15 °C) and only a small percentage of these reach anthesis. To determine if application of the ethylene-releasing compound ethephon can overcome the suppression of female flowers at high temperatures, `Baby Bear' pumpkin plants were sprayed at the two-leaf stage with 100 or 300 μL L–1 ethephon and then grown in hot and cool greenhouse compartments. At 20/15 °C, 17% of the first 15 main stem nodes produced female flower buds on control plants and virtually all of these developed into open flowers. The higher rate of ethephon increased female bud percentage to 37%. At 32/27 °C, only 3% of the nodes formed female flower buds and 2% flowered. Application of ethephon did not significantly increase female expression at high temperature, and none of the buds reached anthesis. Treatment with the inhibitor of ethylene action silver thiosulfate reduced female flower bud formation at the low temperature and entirely suppressed female flower buds at high temperature. In two additional experiments, these treatments were applied to two cultivars grown at a less extreme 32/20 and at 20/15 °C. Female buds and open flowers were moderately increased by ethephon in the high temperatures, suggesting that ethephon might foster female flowering in less extreme temperatures. Further work is needed to determine if ethephon treatment can overcome the heat-induced inhibition of female flowers in pumpkin under field conditions.

Sign in / Sign up

Export Citation Format

Share Document