High-Temperature Operation of Electrostatically-Excited Single-Crystalline 4H-SiC Microcantilever Resonators

2015 ◽  
Vol 821-823 ◽  
pp. 914-918
Author(s):  
Kosuke Sato ◽  
Kohei Adachi ◽  
Hajime Okamoto ◽  
Hiroshi Yamaguchi ◽  
Tsunenobu Kimoto ◽  
...  
Keyword(s):  
High Temperature ◽  
Quality Factor ◽  
Room Temperature ◽  
The Other ◽  
Thermoelastic Damping ◽  
High Quality ◽  
Single Crystalline ◽  
Temperature Dependences ◽  
Increasing Temperature ◽  
High Temperature Operation

We fabricated electrostatically-excited single-crystalline 4H-SiC microcantilever resonators with various thicknesses and lengths. Their resonant characteristics were investigated from room temperature (RT) up to 600°C. The resonant frequency of the cantilevers decreased with increasing temperature. From the results, the temperature dependence of Young’s modulus of single-crystalline 4H-SiC was obtained, i.e., 3% decrement with increasing temperature from RT to 600°C. The cantilevers with different thicknesses showed different temperature dependences of the quality factor. A 2-μm-thick cantilever exhibited a high quality factor (Q) (250,000) at RT and the Q decreased to 6,000 at 600°C, which can be explained by thermoelastic damping. On the other hand, a Q of a 0.45-μm-thick cantilever was still high (50,000) even at 600°C.

Purification of Eucalyptus globulus water prehydrolyzates using the HiTAC process (high-temperature adsorption on activated charcoal)

Holzforschung ◽  
2011 ◽  
Vol 65 (4) ◽  
Author(s):  
Jenny Sabrina Gütsch ◽  
Herbert Sixta
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Adsorption Process ◽  
Value Added ◽  
Sustainable Utilization ◽  
Pulp And Paper Mills ◽  
Paper Mills ◽  
Charcoal Adsorption ◽  
Increasing Temperature ◽  
Value Added Products

Abstract The implementation of biorefinery concepts into existing pulp and paper mills is a key step for a sustainable utilization of the natural resource wood. Water prehydrolysis of wood is an interesting process for the recovery of xylo-oligosaccharides and derivatives thereof, while at the same time cellulose is preserved to a large extent for subsequent dissolving pulp production. The recovery of value-added products out of autohydrolyzates is frequently hindered by extensive lignin precipitation, especially at high temperatures. In this study, a new high-temperature adsorption process (HiTAC process) was developed, where lignin is removed directly after the autohydrolysis, which enables further processing of the autohydrolyzates. The suitability of activated charcoals as a selective adsorbent for lignin under process-relevant conditions (150 and 170°C) has not been considered up to now, because former experiments showed decreasing efficiency of charcoal adsorption of lignin with increasing temperature in the range 20–80°C. In contrast to these results, we demonstrated that the adsorption of lignin at 170°C directly after autohydrolysis is even more efficient than after cooling the hydrolyzate to room temperature. The formation of lignin precipitation and incrustations can thus be efficiently prevented by the HiTAC process. The carbohydrates in the autohydrolysis liquor remain unaffected over a wide charcoal concentration range and can be further processed to yield valuable products.

scholarly journals Creep and Material Design

2012 ◽  
Vol 9 (1) ◽  
pp. 169-171
Author(s):  
Ram Oruganti
Keyword(s):  
High Temperature ◽  
Creep Resistance ◽  
Room Temperature ◽  
Shape Change ◽  
Creep Damage ◽  
Material Design ◽  
The Other ◽  
Permanent Shape ◽  
Total Life

When a material is subjected to temperature and stress, it deforms slowly resulting in permanent shape change. If the same amount of stress were applied at room temperature, the material would not budge. This deformation at high temperature under low stresses is called creep. This phenomenon is important for OEM’S like GE etc. since turbine components are exposed to low stress and high temperature and the resulting shape change is not a desirable consequence. Apart from the change in shape, the components can eventually rupture leading to catastrophic consequences. So it is imperative that the nature of this phenomenon is understood well. Some of the questions to be answered are 1) What makes one material more resistant to creep that the other 2) How can a material’s creep resistance be improved 3) How can the current creep damage in a component be measured 4) Is it possible to say what fraction of the total life of a component has been consumed by creep.

1700V, 5.5mOhm-cm2 4H-SiC DMOSFET with Stable 225°C Operation

2014 ◽  
Vol 778-780 ◽  
pp. 903-906 ◽  
Author(s):  
Kevin Matocha ◽  
Kiran Chatty ◽  
Sujit Banerjee ◽  
Larry B. Rowland
Keyword(s):  
High Temperature ◽  
Temperature Stress ◽  
High Temperatures ◽  
Threshold Voltage ◽  
Room Temperature ◽  
Gate Bias ◽  
Threshold Voltage Shift ◽  
Device Reliability ◽  
Bias Temperature Stress ◽  
High Temperature Operation

We report a 1700V, 5.5mΩ-cm24H-SiC DMOSFET capable of 225°C operation. The specific on-resistance of the DMOSFET designed for 1200V applications is 8.8mΩ-cm2at 225°C, an increase of only 60% compared to the room temperature value. The low specific on-resistance at high temperatures enables a smaller die size for high temperature operation. Under a negative gate bias temperature stress (BTS) at VGS=-15 V at 225°C for 20 minutes, the devices show a threshold voltage shift of ΔVTH=-0.25 V demonstrating one of the key device reliability requirements for high temperature operation.

scholarly journals Semiconducting polymer blends that exhibit stable charge transport at high temperatures

Science ◽  
2018 ◽  
Vol 362 (6419) ◽  
pp. 1131-1134 ◽  
Author(s):  
Aristide Gumyusenge ◽  
Dung T. Tran ◽  
Xuyi Luo ◽  
Gregory M. Pitch ◽  
Yan Zhao ◽  
...  
Keyword(s):  
High Temperature ◽  
Polymer Blends ◽  
Charge Transport ◽  
Organic Semiconductors ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Hole Mobility ◽  
General Strategy ◽  
Semiconducting Polymer ◽  
High Temperature Operation

Although high-temperature operation (i.e., beyond 150°C) is of great interest for many electronics applications, achieving stable carrier mobilities for organic semiconductors at elevated temperatures is fundamentally challenging. We report a general strategy to make thermally stable high-temperature semiconducting polymer blends, composed of interpenetrating semicrystalline conjugated polymers and high glass-transition temperature insulating matrices. When properly engineered, such polymer blends display a temperature-insensitive charge transport behavior with hole mobility exceeding 2.0 cm2/V·s across a wide temperature range from room temperature up to 220°C in thin-film transistors.

ARSENIDES OF THE TRANSITION METALS: II. THE NICKEL ARSENIDES

1957 ◽  
Vol 35 (10) ◽  
pp. 1205-1215 ◽  
Author(s):  
R. D. Heyding ◽  
L. D. Calvert
Keyword(s):  
High Temperature ◽  
Melting Point ◽  
Transition Metals ◽  
Stability Region ◽  
Room Temperature ◽  
Metastable Phase ◽  
The Other ◽  
Incongruent Melting ◽  
Diffraction Patterns ◽  
The Stability

Alloys of nickel and arsenic containing up to 60% As by weight have been studied by means of room temperature and high temperature Debye-Scherrer diagrams. Three compounds have been identified: Ni5As2, Ni12−xAs8 (maucherite), and NiAs (niccolite). The first of these is homogeneous from Ni5As2 to Ni4.8A2 at room temperature, and to Ni4.6As2 above 250 °C., while the latter is homogeneous from NiAs to Ni0.95As. Contrary to expectations the stability region of the compound Ni12−xAs8 is very narrow, and occurs at Ni11As8 rather than at Ni3As2. Evidence is presented in support of Hansen's contention that this compound has an incongruent melting point. Alloys in the region corresponding to Ni4.6As2 undergo two transitions below 200 °C, one of which is martensitic and produces a metastable phase, while the other is believed to result in the formation of a new compound, as yet unidentified. The diffraction patterns are discussed in some detail.

Effect of Temperature on Crater Formation and Ejecta Composition in Aluminum Alloy Targets

2012 ◽  
Vol 706-709 ◽  
pp. 768-773
Author(s):  
Masahiro Nishida ◽  
Koichi Hayashi ◽  
Junichi Nakagawa ◽  
Yoshitaka Ito
Keyword(s):  
Aluminum Alloy ◽  
High Temperature ◽  
Low Temperature ◽  
Room Temperature ◽  
Effect Of Temperature ◽  
Crater Formation ◽  
Influence Of Temperature ◽  
Gas Gun ◽  
Influence Of Temperature On ◽  
Increasing Temperature

The influence of temperature on crater formation and ejecta composition in thick aluminum alloy targets were investigated for impact velocities ranging from approximately 1.5 to 3.5 km/s using a two-stage light-gas gun. The diameter and depth of the crater increased with increasing temperature. The ejecta size at low temperature was slightly smaller than that at high temperature and room temperature. Temperature did not affect the size ratio of ejecta. The scatter diameter of the ejecta at high temperature was slightly smaller than those at low and room temperatures.

Normally-off GaN MOSFETs on Silicon Substrates with High-temperature Operation

2009 ◽  
Vol 1202 ◽  
Author(s):  
Hiroshi Kambayashi ◽  
Yuki Niiyama ◽  
Takehiko Nomura ◽  
Masayuki Iwami ◽  
yoshihiro Satoh ◽  
...  
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Silicon Substrates ◽  
Enhancement Mode ◽  
Threshold Voltages ◽  
Source Voltage ◽  
Gan Hfet ◽  
Output Characteristics ◽  
High Temperature Operation ◽  
State Resistance

AbstractWe have demonstrated enhancement-mode n-channel gallium nitride (GaN) MOSFETs on Si (111) substrates with high-temperature operation up to 300 °C. The GaN MOSFETs have good normally-off operation with the threshold voltages of +2.7 V. The MOSFET exhibits good output characteristics from room temperature to 300 °C. The leakage current at 300°C is less than 100 pA/mm at the drain-to-source voltage of 0.1 V. The on-state resistance of MOSFET at 300°C is about 1.5 times as high as that at room temperature. These results indicate that GaN MOSFET is suitable for high-temperature operation compared with AlGaN/GaN HFET.

High Temperature Implantation in Graphite

1983 ◽  
Vol 27 ◽  
Author(s):  
G. Braunstein ◽  
B.S. Elman ◽  
M.S. Dresselhaus ◽  
G. Dresselhaus ◽  
T. Venkatesan
Keyword(s):  
High Temperature ◽  
Radiation Damage ◽  
High Temperatures ◽  
Room Temperature ◽  
Pyrolytic Graphite ◽  
Rutherford Backscattering ◽  
The Other ◽  
Highly Oriented Pyrolytic Graphite ◽  
Graphite Lattice ◽  
Partial Annealing

ABSTRACTIn previous studies it was found that when highly oriented pyrolytic graphite (HOPG) is implanted at room temperature, the damage caused by the implantation could be completely annealed by heating the sample to temperatures higher than ∼ 2500°C. However at these high temperatures, the implanted species was found to diffuse out of the sample, as evidenced by the disappearance of the impurity peak in the Rutherford backscattering (RBS) spectrum. If, on the other hand, the HOPG crystal was held at a high temperature (≥ 600°C) during the implantation, partial annealing could be observed. The present work further shows that it is possible to anneal the radiation damage and simultaneously to retain the implants in the graphite lattice by means of high temperature implantation (Ti ≥ 450°C) followed by annealing at 2300°C.

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