Comparative Study Of Thermal Stability Research Articles

Comparative study of thermal stability of lithium metal anode in carbonate and ether based electrolytes

The highest specific capacity and the lowest potential make the lithium metal anode an ultimate choice of battery anode and thus becoming a hot topic in the battery research community. Extensive efforts are afforded to improve the electrochemical performances of lithium metal anode and encouraging progresses are made to achieve stable cycling of lithium metal battery. However, the safety issue such as the thermal stability of the lithium metal-based electrode against electrolytes and the practical safety performance of lithium metal batteries, which may be the biggest obstacle for practical application of lithium metal anode, is largely unknown. The present work prepares the metallic lithium deposited in carbonate- and ether-based electrolytes and then compares their thermal stability towards electrolytes. It is found that a significant amount of heat can be generated by the reactions of lithium and electrolyte. The electrolyte solvent, solid electrolyte interphase composition and structure, and lithium deposition morphology are found to impact the thermal behaviors. Based on the thermal behavior of lithium anode, possible thermal runaway reaction chains in lithium metal batteries are revealed and possible modification strategies are proposed, highlighting the important role of electrode/electrolyte interface in achieving high thermal stability of lithium metal anode.

Ceramizable phenolic adhesive modified by different inorganic particles: A comparative study of thermal stability, bonding strength and bonding mechanism

In this work, two ceramizable phenolic adhesives were prepared using ZrSi2 particles or ZrSi2/B4C mix particles as the inorganic fillers. The thermal stability, bonding strength, microstructure and phase composition of the adhesives were investigated by TGA, shear strength of Al2O3 joints, SEM, EDS, XRD and XPS. The results show that these two adhesives have different bonding performances and ceramicization evolutions above 600 °C in air due to the addition of the second phase particles B4C. The bonding strength of ZrSi2/B4C modified phenolic adhesive after treatment at 1200 ℃ can be as high as 36.6 MPa, while the bonding strength of ZrSi2 modified phenolic adhesive under the same conditions is only 17.5 MPa. B4C undergoes oxidation reaction before ZrSi2, and the oxidation product B2O3 liquid phase not only reacts with ZrSi2 to form oxidation-resistant ZrB2, but also can dissolve the high temperatures defects of the adhesive and chemically bond with the Al2O3 substrates at the interface.

Comparative study of thermal stability and crystallization kinetics between melt-spun and bulk Pd77.5Cu6Si16.5 metallic glasses

A comparative study on the thermal stability and kinetics of crystallization of both melt–spun and bulk Pd77.5Cu6Si16.5 metallic glasses was performed. Rapidly quenched Pd77.5Cu6Si16.5 ribbon and as–cast bulk metallic glass (BMG) sample were produced by melt spinning and copper mold casting, respectively. Phase identification and transformation were studied by X–ray diffraction (XRD), transmission electronic microscopy (TEM), and differential scanning calorimeter (DSC) measurements. In non-isothermal conditions, the activation energies were calculated by Moynihan and Kissinger methods, respectively. The nucleation and growth during the crystallization were investigated in the frame work of the local activation energy and the local Avrami exponent. The local activation energy was calculated by Kissinger–Akahira–Sunose, Flynn–Wall–Ozawa and Vyazovkin methods. The local Avrami exponent was calculated. The experimental results indicated that the characteristic temperatures depend on the heating rate. The obtained activation energies indicated that the Pd77.5Cu6Si16.5 amorphous alloys exhibit excellent thermal stability. The thermal stability of Pd77.5Cu6Si16.5 BMG is better than that of ribbon. The local activation energy Ea increases to a maximum and then decreases. It is indicated by local Avrami exponent that the crystallization processes of both Pd77.5Cu6Si16.5 amorphous ribbon and BMG are controlled by volume nucleation with three-dimensional growth with various nucleation rates. The crystallization process of Pd77.5Cu6Si16.5 amorphous ribbon is close to that of BMG. The isothermal crystallization kinetics of Pd77.5Cu6Si16.5 amorphous ribbon is investigated and compared with the results of non-isothermal crystallization kinetics.

Comparative Study of Thermal Stability of Lithium Metal Anode in Carbonate and Ether Based Electrolytes

Comparative Study of Thermal Stability of Lithium Metal Anode in Carbonate and Ether Based Electrolytes

A comparative study of thermal stability of TNT, RDX, CL20 and ANTA explosives using UV 266 nm-time resolved photoacoustic pyrolysis technique.

The paper reports the potential use of UV based pulsed photoacoustic spectroscopy to study the thermal stability of some well-known premier explosives such as TNT, RDX, CL20, and ANTA between 30 and 350 °C range. The thermal PA spectra of samples were recorded using fourth harmonic wavelength i.e. 266 nm of pulse duration 7 ns and repetition rate 10 Hz obtained from Q-switched Nd: YAG laser system. Under the influence of UV radiation, the explosive molecules in vapor phase follow the photodissociation process and converted into their byproducts such as NO, NO2 and N2O etc. due to π* ← n transitions, which are responsible for the generation resultant PA signal at 266 nm wavelength. The results obtained from PA spectra as a function of temperature are cross verified with Thermo gravimetric-differential thermal analysis (TG-DTA) to ascertain the thermal stability of these samples. The comparative PA spectra of samples were analyzed and shown the behavior of acoustic modes with respect to incident laser energy, and data acquisition time. Finally, the thermal quality factor "Q" is measured to test the stability of reported explosives.

Comparative study of thermal stability and combustion of dinitropyrazole isomers

A comparative study of the thermal stability and combustion peculiarities of three dinitropyrazole isomers was carried out. It has been found that the rate-limiting stage of the decomposition of 1,3-dinitropyrazole (1,3-DNP) and 1,4-dinitropyrazole (1,4-DNP) both having the N-bounded nitro group, is the N → C migration of the nitro group rather than its elimination, followed by secondary decomposition reactions of non-aromatic 3H-pyrazole. In the case of 3,4-dinitropyrazole (3,4-DNP) the rate-limiting stage is assumed to be the nitro group elimination. All the studied pyrazole isomers revealed close burning rate vs. pressure dependences despite significant differences in the thermal stability and volatility.

Comparison of Thermal Stability of New Formate Dehydrogenases by Differential Scanning Calorimetry

Formate dehydrogenases (FDHs) from different sources are systematically studied in our laboratory. Over the past few years, new genes of four FDHs from pathogenic bacterium Staphylococcus aureus (SauFDH), methylotrophic thermotolerant yeast Ogataea parapolymorpha (OpaFDH), yeast Saccharomyces cerevisiae (SceFDH), and moss Physcomitrella patens (PpaFDH) have been cloned and expressed in E. coli cells. By means of differential scanning calorimetry, a comparative study of thermal stability of new recombinant formate dehydrogenases and a number of FDHs from other sources has been performed. It was shown that two new enzymes, SauFDH and OpaFDH, are comparable to the FDH from Pseudomonas sp. 101 bacteria in their stability. SceFDH is the least stable FDH among the described formate dehydrogenases.

Influence of A-site cation on the thermal stability of metal halide perovskite polycrystalline films

ABSTRACTThis paper reports a comparative study of thermal stability between all-organic metal halide perovskite (MHP) CsPbBr3 and organic–inorganic hybrid MHP (methylammonium lead bromide MAPbBr3). The film morphology, crystal structure, steady-state photoluminescence intensity, and photoluminescence lifetime of CsPbBr3 and MAPbBr3 polycrystalline films were measured after thermal annealing at temperatures from 70°C to 230°C. The CsPbBr3 films exhibited little change in their structural and luminescent properties after being annealed even at 230°C, whereas the MAPbBr3 films exhibited a significant change in such properties due to their decomposition into PbBr2 when annealed at ≥180°C. This study increased the understanding of the difference in the thermal stability of MHP polycrystalline films with different A-site cations.

Comparative Study of Thermal Stability, Morphology, and Performance of All-Polymer, Fullerene–Polymer, and Ternary Blend Solar Cells Based on the Same Polymer Donor

We compared the thermal and morphological stability of all-polymer solar cells (all-PSCs) and fullerene-based PSCs (fullerene-PSCs) having the same polymer donor (PBDTTTPD), which provided comparable peak power conversion efficiencies (PCEs) of >6%. We observed a remarkable contrast in thermal stability dependent upon the acceptor composition in the active layer, with the performance of the fullerene-PSCs completely deteriorating after annealing for 5 h at 150 °C, whereas that of the all-PSCs remained stable even after annealing for 50 h at 150 °C. Pronounced phase separation was observed in the active layer of the fullerene-PSCs at two different length scales. In stark contrast, almost no morphological changes in the all-PSCs were observed, likely due to the low diffusion kinetics of the polymer acceptors. To develop a comprehensive understanding of the role of polymer acceptor on the thermal stability of devices, the morphology of ternary blend active layers composed of PBDTTTPD:polymer acceptor:fullere...

Comparative Study of Thermal Stability of NiFe and NiFeTa Thin Films Grown by Cosputtering Technique

A comparative study of the thermal behavior of dynamic permeability spectra for compositionally graded NiFeTa and uniform-composition NiFe thin films has been carried out. We found that the resonance frequency of the compositionally graded NiFeTa film increased with increasing temperature, while it decreased for the case of the uniform-composition NiFe thin film. This finding unambiguously suggests that the compositional gradient of the film is the only reason for the increase of the magnetic anisotropy with temperature due to its stress-induced origin, while the cosputtering technique does not play any role in this peculiar behavior. The temperature dependence of the frequency linewidth is also presented and discussed.

Comparative study of thermal stability of aluminium- and gallium-doped ZnO thin films prepared by sol–gel method

To study the thermal stability of Al- and Ga-doped ZnO (AZO and GZO) films, these films with a doping concentration from 0·5 to 3 at-% have been prepared by sol–gel method on glass substrate followed by annealing in air. It has been found out that the AZO and GZO films have similar thermal stability, and Ga dopant cannot improve the stability. Moreover, the doping concentration has no prominent effect on the thermal stability. The resistivity of the films is stable when the annealing temperature is lower than 250°C and increases rapidly after that, while the transmittance increases with annealing temperature. The variations of the resistivity and the transmittance are closely related to the microstructure, and vacancy and electron concentration affected by the annealing treatment.

Comparative study of thermal stability of magnetostrictive biosensor between two kinds of biorecognition elements

Magnetostrictive biosensors specific to Salmonella typhimurium were prepared by immobilizing antibody or phage as biorecognition elements onto the magnetostrictive sensor platform. The sensors were stored at temperatures of 25°C (room temperature), 45°C and 65°C, respectively, and the ability to bind S. typhimurium was detected by testing the resonant frequency shift using a HP network analyzer after exposure to 1mL of 1×109cfu/mL of S. typhimurium at a predetermined schedule. The binding of S. typhimurium to biosensors was confirmed by Scanning Electron Microscopy (SEM). The results showed that there existed an initial sudden drop in the average density of S. typhimurium bound to the biosensor surface versus duration at different temperatures for the two kinds of recognition elements, and the binding ability to S. typhimurium of phage-immobilized biosensors was much better than that of antibody-immobilized biosensors, with longevity longer than 30days at all tested temperatures, though decreasing gradually over the testing period. While the longevity of antibody-immobilized biosensors was only about 30, 8 and 5days at room temperature (25°C), 45°C and 65°C, respectively. Meanwhile, the activation energy of the two kinds of biosensors was investigated, and it was found that phage immobilized sensors showed much higher activation energy than antibody immobilized sensors, which resulted in less dependency on temperature and thus having much better thermal stability than antibody immobilized sensors.

Thermally robust RuOx Schottky diodes and HEMTs on III‐nitrides

AbstractThe potential usage of thermally robust RuOx Schottky contacts in III‐nitride‐based Schottky diodes and high electron mobility transistors (HEMTs) has been investigated. RuOx is deposited on nitride surface by sputtering Ru in Ar/O2 ambient. The influence of post sputtering annealing ambient and temperature on the characteristics of RuOx Schottky diodes on n‐type GaN on Si(111) substrate is addressed. We also report the comparative study of thermal stability between RuOx and Ni/Au Schottky diodes on InxAl1‐xN/GaN on Si(111) substrate in terms of the reverse bias leakage current and Schottky barrier height (SBH). RuOx contact shows a higher SBH of 1.24 eV and a lower leakage current of ∼10‐5 Acm‐2 (∼four orders of magnitude lower than that of Ni/Au) on InxAl1‐xN/GaN at –40 V after annealing at 800 oC in N2. In addition, RuOx Schottky gate HEMT on InxAl1‐xN/GaN on Si(111) substrate has shown a low gate leakage current of ∼6×10‐8 A/mm at ‐8 V after annealing at 700 oC in N2 for 1 minute. The lower gate leakage current has resulted in a transistor ON/OFF current ratio of ∼105. The maximum transconductance and ON‐resistance achieved by such HEMTs are about 0.18 S/mm and 8.33 Ωmm, respectively, for a gate length of 1.5 µm. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

Comparative study of thermal stability and crystallization kinetics of 70B 2O 3–30Bi 2O 3 and 70B 2O 3–30PbO glasses

Glasses with compositions 70B 2O 3–30Bi 2O 3 and 70B 2O 3–30PbO have been prepared and studied by differential thermal analysis (DTA). The crystallization kinetics of the glasses were investigated under non-isothermal conditions. From the dependence of glass-transition temperature ( T g ) on heating rate, the activation energy for the glass transition was derived. Similarly the activation energy of the crystallization process was determined. Thermal stability of these glasses were achieved in terms of the characteristic temperatures, such as glass-transition temperature, T g , onset temperature of crystallization, T in , temperature corresponding to the maximum crystallization rate, T p , beside the kinetic parameters, K( T g ) and K( T p ). The results revealed that 70B 2O 3–30PbO is more stable than 70B 2O 3–30Bi 2O 3. The crystallization mechanism is characterized for both 70B 2O 3–30Bi 2O 3 and 70B 2O 3–30PbO glasses (kinetic exponent n=2.06 for 70B 2O 3–30Bi 2O 3, and n=3.03 for 70B 2O 3–30PbO). The phases at which the glass crystallizes after the thermal process were identified by X-ray diffraction.

Semi-rational chemical modification of endoinulinase by pyridoxal 5′-phosphate and ascorbic acid

It is important to improve the quality of the enzyme inulinase used in industrial applications without allowing the treatment to have any adverse effects on enzyme activity. We achieved preferential chemical modification of the non-catalytic domain of endoinulinase (EC 3.2.1.7) to enhance the thermostability of the enzyme. We used pyridoxal 5′-phosphate (PLP) to modify the more accessible lysine residues at the surface of endoinulinase and then performed a necessary step of reduction with ascorbate. Endoinulinase was incubated in the presence of PLP at various concentrations; this step was followed by reduction of the resulting Schiff base and dialysis. The effects of different PLP concentrations and incubation times on enzyme modification were evaluated. Enzyme deactivation was observed immediately after treatment, even at low PLP concentrations, while reactivation was observed for samples treated with low PLP concentrations after a period of time. Structural analysis revealed that the α-helix content increased from 13.60% to 17.60% after applying the modification strategy; consequently, enzyme stabilization was achieved. The melting temperature ( T m ) of the modified enzyme increased from 64.1 °C to 72.2 °C, and a comparative study of thermal stability at 25 °C, 45 °C, and 50 °C for 150 min confirmed that the enzyme was stabilized because of increase in its half-life ( t 1/2) after PLP modification/ascorbate reduction. The modification process was optimized to achieve the optimum mole ratio for the PLP/endoinulinase (1.37). Excess moles of the modifier are thought to be responsible for enzyme deactivation through unwanted/nonspecific and noncovalent interactions, and the optimization ensured that there was no excess modifier after the desired covalent reaction was complete.

The comparative study of thermal stability among silicon dioxide, fluorinated silicate glass, hydrogen silsesquioxane, and organosilicate glass dielectrics on silicon

This study investigates the thermal stability of thermally grown silicon dioxide (thermal SiO 2), fluorinated silicate glass (FSG), hydrogen silsesquioxane (HSQ), and organosilicate glass (OSG). Samples with and without sputtered copper films, as-prepared and after annealing at 200 ∼ 800 °C in vacuum, have been investigated by various methods of analysis. For the as-prepared dielectrics, it is found that the densities of HSQ and OSG are less than those of SiO 2 and FSG due to the greater roughness and more porous structure of HSQ and OSG. After annealing at 800 °C, the HSQ structure converts to a SiO 2-like structure, which is mainly due to decomposition of HSQ. Furthermore, the methyl groups and oxygen atoms are also liberated from OSG after high temperature annealing. A plateau in the Cu profile near the Cu/dielectric interface is observed in the results of secondary ion mass spectrometry after annealing at 450 °C. On the other hand, penetration of Cu atoms across the interface between Cu and HSQ, and across the interface between Cu and OSQ, are observed for Cu/HSQ and Cu/OSG systems after annealing at 450 °C. The thermal stability of these four dielectrics are discussed and compared.

Thermal stability of fission tracks in natural and synthetic glasses: An assessment of compositional effects

A series of laboratory annealing experiments are designed to evaluate the thermal annealing characteristics of fission tracks for a large number of glasses of varying chemical compositions. A comparative study of thermal stability has been made by comparing the calculated value of activation energy (Ea) for each glass. The present investigations suggest that fission tracks in glass samples with a high silica content are more resistant to annealing than those with a low silica content. In addition, the influence of chemical composition on etching characteristics for both synthetic and natural glasses has also been investigated.

Effect of m-carboranic group content on the thermal stability of polyarylates containing carborane

A comparative study of thermal stability of polyarylates with varying m-carborane nucleus content in the macromolecular chain shows that, according to the concentration of the m-carborane group, both the temperature of initial decomposition of the polymer and the amount and composition of gaseous products of degradation change. It is indicated that the difference in the concentration of the m-carborane group in the polymer chain influences the thermal degradation mechanism of the polyesters studied.