Stabilization of high temperature hexagonal phase of SrAl2O4 at room temperature: role of ZnO

2014 ◽  
Vol 43 (14) ◽  
pp. 5309 ◽  
Author(s):  
V. P. Singh ◽  
S. B. Rai ◽  
H. Mishra ◽  
Chandana Rath
Keyword(s):  
High Temperature ◽  
Room Temperature ◽  
Hexagonal Phase

The Role of Callistemon Fruits and Infructescences in Protecting Seeds from Heat in Fires

1998 ◽  
Vol 46 (2) ◽  
pp. 235 ◽  
Author(s):  
Claire L. Brown ◽  
Robert J. Whelan
Keyword(s):  
High Temperature ◽  
Seed Germination ◽  
High Intensity ◽  
Room Temperature ◽  
Seed Viability ◽  
Protective Role ◽  
Percentage Germination ◽  
Low Intensity ◽  
Australian Plant

A number of Australian plant species tolerate fires because seeds are protected in woody fruits and are released after fire, but there is little information about the role of the fruit, or a collection of fruits, in protecting seed from the heat of a fire. This study examined the effects of various temperatures applied to infructescences of Callistemon citrinus (Curtis) Skeels on seed germination. The protective role of the dense collection of fruits in maintaining seed viability was tested by experimentally ‘thinning’ infructescences before heating. Heating of infructescences significantly increased the percentage of seeds germinating from less than 20% at room temperature to over 35% at 200˚C, but caused a decline, with further temperature increase to 800˚C. There was a slight but statistically significant increase in the percentage germination of seeds from thinned infructescences. Increased germination following exposure to high temperature may be a way for a plant to synchronise germination after high-intensity fire, while spreading it out if seeds are released in the absence of fire or after a low-intensity fire.

Multifunctional role of dysprosium in HfO2: stabilization of the high temperature cubic phase, and magnetic and photoluminescence properties

2017 ◽  
Vol 19 (29) ◽  
pp. 18957-18967 ◽  
Author(s):  
Sandeep Kumar ◽  
S. B. Rai ◽  
Chandana Rath
Keyword(s):  
High Temperature ◽  
Hafnium Oxide ◽  
Room Temperature ◽  
Cubic Phase ◽  
Photoluminescence Properties ◽  
Crystalline Structures

Hafnium oxide (HfO2) can exist in different crystalline structures such as monoclinic at room temperature, tetragonal at 1700 °C and cubic at 2600 °C.

ABOUT HEAT CAPACITY OF TITANIUM CARBIDE TiCx

2019 ◽  
pp. 56-66
Author(s):  
I. Khidirov ◽  
V. V. Getmanskiy ◽  
A. S. Parpiev ◽  
Sh. A. Makhmudov
Keyword(s):  
Heat Capacity ◽  
High Temperature ◽  
Titanium Carbide ◽  
Temperature Dependence ◽  
Carbon Concentration ◽  
Room Temperature ◽  
Thermodynamic Characteristics ◽  
Liquid Nitrogen Temperature ◽  
Analysis Data ◽  
Thermal Excitation

This work relates to the field of thermophysical parameters of refractory interstitial alloys. The isochoric heat capacity of cubic titanium carbide TiCx has been calculated within the Debye approximation in the carbon concentration  range x = 0.70–0.97 at room temperature (300 K) and at liquid nitrogen temperature (80 K) through the Debye temperature established on the basis of neutron diffraction analysis data. It has been found out that at room temperature with decrease of carbon concentration the heat capacity significantly increases from 29.40 J/mol·K to 34.20 J/mol·K, and at T = 80 K – from 3.08 J/mol·K to 8.20 J/mol·K. The work analyzes the literature data and gives the results of the evaluation of the high-temperature dependence of the heat capacity СV of the cubic titanium carbide TiC0.97 based on the data of neutron structural analysis. It has been proposed to amend in the Neumann–Kopp formula to describe the high-temperature dependence of the titanium carbide heat capacity. After the amendment, the Neumann–Kopp formula describes the results of well-known experiments on the high-temperature dependence of the heat capacity of the titanium carbide TiCx. The proposed formula takes into account the degree of thermal excitation (a quantized number) that increases in steps with increasing temperature.The results allow us to predict the thermodynamic characteristics of titanium carbide in the temperature range of 300–3000 K and can be useful for materials scientists.

Nanocomposite Polyurethane Foams Via POSS Blends

2002 ◽  
Vol 733 ◽  
Author(s):  
Brock McCabe ◽  
Steven Nutt ◽  
Brent Viers ◽  
Tim Haddad
Keyword(s):  
High Temperature ◽  
Sample Preparation ◽  
Room Temperature ◽  
Focused Ion Beam ◽  
Ion Beam ◽  
Polyurethane Foams ◽  
Development Projects ◽  
Polymer Systems ◽  
Polyurethane Resin ◽  
Military Development

AbstractPolyhedral Oligomeric Silsequioxane molecules have been incorporated into a commercial polyurethane formulation to produce nanocomposite polyurethane foam. This tiny POSS silica molecule has been used successfully to enhance the performance of polymer systems using co-polymerization and blend strategies. In our investigation, we chose a high-temperature MDI Polyurethane resin foam currently used in military development projects. For the nanofiller, or “blend”, Cp7T7(OH)3 POSS was chosen. Structural characterization was accomplished by TEM and SEM to determine POSS dispersion and cell morphology, respectively. Thermal behavior was investigated by TGA. Two methods of TEM sample preparation were employed, Focused Ion Beam and Ultramicrotomy (room temperature).

Clustering-Triggered Efficient Room Temperature Phosphorescence from Nonconventional Luminophores

2019 ◽  
Author(s):  
Shuyuan Zheng ◽  
Taiping Hu ◽  
Xin Bin ◽  
Yunzhong Wang ◽  
Yuanping Yi ◽  
...  
Keyword(s):  
Room Temperature ◽  
High Efficiency ◽  
Spin Orbit Coupling ◽  
Design Rationale ◽  
Emission Mechanism ◽  
Room Temperature Phosphorescence ◽  
Electronic Interactions ◽  
Energy Gaps ◽  
Theoretical Results

Pure organic room temperature phosphorescence (RTP) and luminescence from nonconventional luminophores have gained increasing attention. However, it remains challenging to achieve efficient RTP from unorthodox luminophores, on account of the unsophisticated understanding of the emission mechanism. Here we propose a strategy to realize efficient RTP in nonconventional luminophores through incorporation of lone pairs together with clustering and effective electronic interactions. The former promotes spin-orbit coupling and boost the consequent intersystem crossing, whereas the latter narrows energy gaps and stabilizes the triplets, thus synergistically affording remarkable RTP. Experimental and theoretical results of urea and its derivatives verify the design rationale. Remarkably, RTP from thiourea solids with unprecedentedly high efficiency of up to 24.5% is obtained. Further control experiments testify the crucial role of through-space delocalization on the emission. These results would spur the future fabrication of nonconventional phosphors, and moreover should advance understanding of the underlying emission mechanism.<br>

FANSTEEL 85 METAL

Alloy Digest ◽  
1981 ◽  
Vol 30 (6) ◽  
Keyword(s):  
High Temperature ◽  
Physical Properties ◽  
Creep Strength ◽  
Room Temperature ◽  
Elevated Temperatures ◽  
Base Alloy ◽  
Heat Treating ◽  
Good Combination ◽  
Bend Strength ◽  
Temperature Performance

Abstract FANSTEEL 85 METAL is a columbium-base alloy characterized by good fabricability at room temperature, good weldability and a good combination of creep strength and oxidation resistance at elevated temperatures. Its applications include missile and rocket components and many other high-temperature parts. This datasheet provides information on composition, physical properties, microstructure, hardness, elasticity, tensile properties, and bend strength as well as creep. It also includes information on low and high temperature performance as well as forming, heat treating, machining, joining, and surface treatment. Filing Code: Cb-7. Producer or source: Fansteel Metallurgical Corporation. Originally published December 1963, revised June 1981.

MAGNESIUM AZ31B

Alloy Digest ◽  
1962 ◽  
Vol 11 (9) ◽  
Keyword(s):  
High Temperature ◽  
Magnesium Alloy ◽  
Physical Properties ◽  
Room Temperature ◽  
Heat Treating ◽  
General Purpose ◽  
Bearing Strength ◽  
Temperature Performance ◽  
Wrought Magnesium Alloy ◽  
Metal Products

Abstract Magnesium AZ31B is a general purpose wrought magnesium alloy for room temperature service. This datasheet provides information on composition, physical properties, hardness, elasticity, tensile properties, and compressive, shear, and bearing strength as well as creep. It also includes information on low and high temperature performance as well as forming, heat treating, machining, and joining. Filing Code: Mg-53. Producer or source: The Dow Metal Products Company.

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